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Thermal Performance of Vegetative Roofing Systems
SciTech Connect
Vegetative roofing, otherwise known as green or garden roofing, has seen tremendous growth in the last decade in the United States. The numerous benefits that green roofs provide have helped to fuel their resurgence in industrial and urban settings. There are many environmental and economical benefits that can be realized by incorporating a vegetative roof into the design of a building. These include storm-water retention, energy conservation, reduction in the urban heat island effect, increased longevity of the roofing membrane, the ability of plants to create biodiversity and filter air contaminants, and beautification of the surroundings by incorporating green space. The vegetative roof research project at Oak Ridge National Laboratory (ORNL) was initiated to quantify the thermal performance of various vegetative roofing systems relative to black and white roofs. Single Ply Roofing Institute (SPRI) continued its long-term commitment to cooperative research with ORNL in this project. Low-slope roof systems for this study were constructed and instrumented for continuous monitoring in the mixed climate of East Tennessee. This report summarizes the results of the annual cooling and heating loads per unit area of three vegetative roofing systems with side-by-side comparison to black and white roofing systems as well as a test section with just the growing media without plants. Results showed vegetative roofs reduced heat gain (reduced cooling loads) compared to the white control system due to the thermal mass, extra insulation, and evapo-transpiration associated with the vegetative roofing systems. The 4-inch and tray systems reduced the heat gain by approximately 61%, while the reduction with the 8-inch vegetative roof was found to be approximately 67%. The vegetative roofing systems were more effective in reducing heat gain than in reducing heat losses (heating loads). The reduction in heat losses for the 4-inch and tray systems were found to be approximately 40% in the mixed climate of East Tennessee. It should be noted that these values are climate dependent. Vegetative roofs also reduced the temperature (heat exposure) and temperature fluctuations (thermal stress) experienced by the membrane. In the cooling season of East Tennessee, the average peak temperature of the 4-inch and tray systems was found to be approximately 94 F cooler than the control black roofing system. The average temperature fluctuations at the membrane for the 4-inch and tray systems were found to be approximately 10 F compared to 125 F for black and 64 F for white systems. As expected, the 8-inch vegetative roof had the lowest fluctuations at approximately 2 F. Future work will include modeling of the energy performance of vegetative roof panels in the test climate of East Tennessee. The validated model then will be used to predict energy use in roofs with different insulation levels and in climates different from the test climate.
Desjarlais, Andre Omer [ORNL; Zaltash, Abdolreza [ORNL; Atchley, Jerald Allen [ORNL; Ennis, Mike J [ORNL
Weather effect on thermal and energy performance of an extensive tropical green roof
Microsoft Academic Search
This study investigated the weather effect on thermal performance of a retrofitted extensive green roof on a railway station in humid-subtropical Hong Kong. Absolute and relative (reduction magnitude) ambient and surface temperatures recorded for two years were compared amongst antecedent bare roof, green roof, and control bare roof. The impacts of solar radiation, relative humidity, soil moisture and wind speed
C. Y. Jim; Lilliana L. H. Peng
A parametric study of the thermal performance of green roofs in different climates through energy modeling
NASA Astrophysics Data System (ADS)
In recent years, there has been great interest in the potential of green roofs as an alternative roofing option to reduce the energy consumed by individual buildings as well as mitigate large scale urban environmental problems such as the heat island effect. There is a widespread recognition and a growing literature of measured data that suggest green roofs can reduce building energy consumption. This thesis investigates the potential of green roofs in reducing the building energy loads and focuses on how the different parameters of a green roof assembly affect the thermal performance of a building. A green roof assembly is modeled in Design Builder- a 3D graphical design modeling and energy use simulation program (interface) that uses the EnergyPlus simulation engine, and the simulated data set thus obtained is compared to field experiment data to validate the roof assembly model on the basis of how accurately it simulates the behavior of a green roof. Then the software is used to evaluate the thermal performance of several green roof assemblies under three different climate types, looking at the whole building energy consumption. For the purpose of this parametric simulation study, a prototypical single story small office building is considered and one parameter of the green roof is altered for each simulation run in order to understand its effect on building's energy loads. These parameters include different insulation thicknesses, leaf area indices (LAI) and growing medium or soil depth, each of which are tested under the three different climate types. The energy use intensities (EUIs), the peak and annual heating and cooling loads resulting from the use of these green roof assemblies are compared with each other and to a cool roof base case to determine the energy load reductions, if any. The heat flux through the roof is also evaluated and compared. The simulation results are then organized and finally presented as a decision support tool that would facilitate the adoption and appropriate utilization of green roof technologies and make it possible to account for green roof benefits in energy codes and related energy efficiency standards and rating systems such as LEED.
Mukherjee, Sananda
Experimental study on thermal performance of improved open-web roofs with induced ventilation
The double layer open-web roof structure is a type of heat preservation and insulation roof structures, in particular suitable for medium and large span roof structures. However, the construction procedures for traditional open-web roof structures are rather complicated because of the built-in molds in the cavity. On the other hand, passive ventilation is an effective route to enhance the thermal
Nan Xiao; Liqiang Sun; Huapeng Chen; Xiang Wang
Performance evaluation of green roof and shading for thermal protection of buildings
The present paper describes a mathematical model for evaluating cooling potential of green roof and solar thermal shading in buildings. A control volume approach based on finite difference methods is used to analyze the components of green roof, viz. green canopy, soil and support layer. Further, these individual decoupled models are integrated using Newton's iterative algorithm until the convergence for
Rakesh Kumar; S. C. Kaushik
CFD modelling and thermal performance analysis of a wooden ventilated roof structure
Thermal comfort and energy saving are objectives of key significance that building design must meet. Since a low energy building\\u000a can be obtained as a result of the good realization of all its components, roofs call for particular attention as they represent\\u000a a large part of a building�s total surface area. In this paper the benefit of using ventilated roofs
Giacomo Villi; Wilmer Pasut; Michele De Carli
Prolong Your Roof's Performance: Roof Asset Management.
ERIC Educational Resources Information Center
Discusses the roof asset management process for maintaining a roof system's integrity and value in a cost-effective manner. Included is a breakdown of roofing surface characteristics for multiply and single ply roofing systems. (GR)
Teitsma, Jerry
Technical viability of alternative blowing agents in polyisocyanurate roof insulation. Part 4, In-situ thermal aging and performance in different roof systems: (Progress report).
National Technical Information Service (NTIS)
This paper presents a progress report on field thermal performance measurements on a set of private industry-produced, experimental polyisocyanurate laminate board stock foams blown with CFC-11, HCFC-123, HCFC-141b, 50/50, and 65/35 blends of HCFC-123/HCF...
J. E. Christian G. E. Courville R. L. Linkous R. L. Wendt R. S. Graves
Roof Integrated Solar Absorbers: The Measured Performance of 'Invisible' Solar Collectors: Preprint.
The Florida Solar Energy Center (FSEC), with the support of the National Renewable Energy Laboratory, has investigated the thermal performance of solar absorbers that are an integral, yet indistinguishable, part of a building's roof. The first roof-integr...
C. J. Colon
Correlating thermal transmittance limits of walls and roofs to orientation and solar absorption
The presented research addresses the association of maximum thermal transmittance (U value) of walls and roofs with orientation and solar absorption. The study is performed on walls and a roof typically used in Kuwait when subjected to local hot climate conditions. A computer program employing the total equivalent temperature difference (TETD) method is developed to estimate the U values corresponding
E. O. Assem
Validation of the Thermal Effect of Roof-Spraying and Green Plants in an Insulated Building.
In recent years, roof-spraying and rooftop lawns have proven effective on roofs with poor thermal insulation. However, the roofs of most buildings have insulating material to provide thermal insulation during the winter. The effects of insulation has not ...
N. Zhou W. Gao C. Marnay M. Nishida T. Ojima
Wind performance evaluation of fully bonded roofing assemblies
Wind performance investigation is critical in the design of durable roofing assemblies. In North America, mainly two types of low slope roofs, conventional and inverted, are in practice depending on the placement of the membrane in the system. The present study focuses on the wind uplift performance of fully bonded single ply roofing assembly. Past studies focused on the wind
A. Baskaran; S. Molleti; M. Sexton
Design, construction and performance prediction of integrated solar roof collectors using finite element analysis
An integrated roof solar collector was designed to achieve ease of construction, energy efficiency, functional integration, composite behavior, sustainability, reliability, flexibility, and cost effectiveness. A construction strategy was developed for the collector to ensure quality, ease and repeatability of manufacturing. Three-dimensional (3D) finite element models were then developed to evaluate the thermal performance of the integrated roof solar collector. The
Marwa M. Hassan; Yvan Beliveau
Roof heat loss detection using airborne thermal infrared imagery
As part of the Austrian and European attempt to reduce energy consumption and greenhouse gas emissions, thermal rehabilitation and the improvement of the energy efficiency of buildings became an important topic in research as well as in building construction and refurbishment. Today, in-situ thermal infrared measurements are routinely used to determine energy loss through the building envelope. However, in-situ thermal surveys are expensive and time consuming, and in many cases the detection of the amount and location of waste heat leaving building through roofs is not possible with ground-based observations. For some years now, a new generation of high-resolution thermal infrared sensors makes it possible to survey heat-loss through roofs at a high level of detail and accuracy. However, to date, comparable studies have mainly been conducted on buildings with uniform roof covering and provided two-dimensional, qualitative information. This pilot study aims to survey the heat-loss through roofs of the buildings of the University of Graz (Austria) campus by using high-resolution airborne thermal infrared imagery (TABI 1800 - Thermal Airborne Broadband imager). TABI-1800 acquires data in a spectral range from 3.7 - 4.8 micron, a thermal resolution of 0.05 �C and a spatial resolution of 0.6 m. The remote sensing data is calibrated to different roof coverings (e.g. clay shingle, asphalt shingle, tin roof, glass) and combined with a roof surface model to determine the amount of waste heat leaving the building and to identify hot spots. The additional integration of information about the conditions underneath the roofs into the study allows a more detailed analysis of the upward heat flux and is a significant improvement of existing methods. The resulting data set provides useful information to the university facility service for infrastructure maintenance, especially in terms of attic and roof insulation improvements. Beyond that, the project is supposed to raise public awareness in the context of climate-neutral actions, and in a long run, contribute to significantly reduce energy consumption and GHG emissions.
Kern, K.; Bauer, C.; Sulzer, W.
This paper reports on the results of three of the tests performed on the Nebraska modified roof pond. During the summer of 1985,? with the test room decoupled from the roof pond itself, several series of tests were initiated. The first experiment (fig. 1) was to test the overall response of the system by forcing the temperature in storage to
Bing Chen; Raymond Guenther; John Maloney; John Kasher
Performance of dryland and wetland plant species on extensive green roofs
PubMed Central
Background and Aims Green roofs are constructed ecosystems where plants perform valuable services, ameliorating the urban environment through roof temperature reductions and stormwater interception. Plant species differ in functional characteristics that alter ecosystem properties. Plant performance research on extensive green roofs has so far indicated that species adapted to dry conditions perform optimally. However, in moist, humid climates, species typical of wetter soils might have advantages over dryland species. In this study, survival, growth and the performance of thermal and stormwater capture functions of three pairs of dryland and wetland plant species were quantified using an extensive modular green roof system. Methods Seedlings of all six species were germinated in a greenhouse and planted into green roof modules with 6 cm of growing medium. There were 34 treatments consisting of each species in monoculture and all combinations of wet- and dryland species in a randomized block design. Performance measures were survival, vegetation cover and roof surface temperature recorded for each module over two growing seasons, water loss (an estimate of evapotranspiration) in 2007, and albedo and water capture in 2008. Key Results Over two seasons, dryland plants performed better than wetland plants, and increasing the number of dryland species in mixtures tended to improve functioning, although there was no clear effect of species or habitat group diversity. All species had survival rates >75 % after the first winter; however, dryland species had much greater cover, an important indicator of green roof performance. Sibbaldiopsis tridentata was the top performing species in monoculture, and was included in the best treatments. Conclusions Although dryland species outperformed wetland species, planting extensive green roofs with both groups decreased performance only slightly, while increasing diversity and possibly habitat value. This study provides further evidence that plant composition and diversity can influence green roof functions.
MacIvor, J. Scott; Ranalli, Melissa A.; Lundholm, Jeremy T.
Study on the damage of the floating roof due to thermal stress
Several cracks were found on some actual floating roof of the crude oil tank in southern Japan. We assumed that one of causes is due to thermal stress during the day. In order to figure out whether the thermal stress could cause damages on the floating roof, strain and temperature were measured on the actual floating roof by using optical
Y. Hirokawa; M. Yamada; H. Nishi; S. Zama; K. Hatayama
An updated and expanded set of thermal property data for green roof growing media
Vegetated (green) roofs alter the roof surface energy balance and hence affect both building energy consumption and the transport of heat into the environment. Quantitative evaluation of the energetics of green roof systems requires accurate knowledge of the moisture-dependent thermal properties of the growing media. To support this need for data and to supplement previously published data we conducted a
D. J. Sailor; M. Hagos
A modelling study of long term green roof retention performance.
This paper outlines the development of a conceptual hydrological flux model for the long term continuous simulation of runoff and drought risk for green roof systems. A green roof's retention capacity depends upon its physical configuration, but it is also strongly influenced by local climatic controls, including the rainfall characteristics and the restoration of retention capacity associated with evapotranspiration during dry weather periods. The model includes a function that links evapotranspiration rates to substrate moisture content, and is validated against observed runoff data. The model's application to typical extensive green roof configurations is demonstrated with reference to four UK locations characterised by contrasting climatic regimes, using 30-year rainfall time-series inputs at hourly simulation time steps. It is shown that retention performance is dependent upon local climatic conditions. Volumetric retention ranges from 0.19 (cool, wet climate) to 0.59 (warm, dry climate). Per event retention is also considered, and it is demonstrated that retention performance decreases significantly when high return period events are considered in isolation. For example, in Sheffield the median per-event retention is 1.00 (many small events), but the median retention for events exceeding a 1 in 1�yr return period threshold is only 0.10. The simulation tool also provides useful information about the likelihood of drought periods, for which irrigation may be required. A sensitivity study suggests that green roofs with reduced moisture-holding capacity and/or low evapotranspiration rates will tend to offer reduced levels of retention, whilst high moisture-holding capacity and low evapotranspiration rates offer the strongest drought resistance. PMID:24178313
Stovin, Virginia; Po�, Simon; Berretta, Christian
The extraction of roof tops from thermal imagery for analyzing the urban heat island structure
Earlier works have analyzed the urban heat island structure from thermal infra?red images; however, the analysis was affected by rooftops which added a component of temperature above ground level. To allow the study of ground level data alone, the roof tops of buildings had to be removed from the image. An image processing technique was developed for removing the roof
M. Shoshany; R. Aminov; Y. Goldreich
Impact of air intrusion on the wind uplift performance of fully bonded roofing assemblies
Wind performance investigation is critical in the design of durable roofing assemblies. In North America, mainly two types of low slope roofs, conventional and inverted, are in practice depending on the placement of the membrane in the assembly. As part of the conventional low-sloped roofs, in a fully bonded assembly (FBA) the insulation is mechanically attached and waterproof membrane is
A. Baskaran; S. Molleti
Thermal resistance of prototypical cellular plastic roof insulations.
A cooperative industry/government project was initiated in 1989 to evaluate the viability of alternative hydrochlorofluorocarbons (HCFCs) as blowing agents in polyisocyanurate (PIR) boardstock for roofing applications. Five sets of PIR boardstock were pro...
D. L. McElroy R. S. Graves F. J. Weaver
In-situ aging of roof systems containing polyisocyanurate roof insulation foamed with alternative blowing agents.
Experimental polyisocyanurate (PIR) foam roof insulations with permeable facers were installed in roofing systems and continuously monitored for thermal performance for four years. The foams were produced using a specific formulation that represented curr...
A. O. Desjarlais J. E. Christian R. S. Graves
Validation on the thermal effect of roof with the spraying and green plants in an insulated building
In recent years, roof-spraying and rooftop lawns has proved effective on roofs with poor thermal insulation. However, roofs of most buildings have insulating material to provide thermal insulation during the winter. The effects of such a practice have not previously been quantified. In this study, the authors conducted measurements of an insulated building to quantify the thermal effects of roof-spraying and rooftop lawns. Roof-spraying did not significantly reduce cooling loads, and required significant amounts of water. The conclusion is that roof spraying is not suitable for buildings with well-insulated roofs. Rooftop lawns, however, significantly stabilized the indoor temperature while additionally helping to mitigate the heat island phenomenon.
Zhou, Nan; Gao, Weijun; Nishida, Masaru; Ojima, Toshio
Observations from a Field Study of the Performance of Polymer-Modified Bitumen Roofing.
The report presents the results of a field study of polymer-modified bitumen roofing. Observations on in-service performance are beneficial for identifying field problems that require study to attain solutions. Fifty-three roofs, ranging in age from 24 to...
W. J. Rossiter R. D. Denchfield
Thermal Comparison of Reflective and Non-Reflective Roofs with Thin-Film Solar Panels
The present paper illustrates an experimental and comparative thermal analysis of reflective (white) and non-reflective (black) roofing membranes paired with thin-film solar photovoltaic panels. Tests were carried out on two different membranes, thermoplastic olefin (TPO), and ethylene propylene diene monomer (EPDM). Solar irradiance along with temperature readings on the surface, between the panel and membrane, and below the membrane were
Grant Irvine; Serdar Celik
Roof-top solar energy potential under performance-based building energy codes: The case of Spain
The quantification at regional level of the amount of energy (for thermal uses and for electricity) that can be generated by using solar systems in buildings is hindered by the availability of data for roof area estimation. In this note, we build on an existing geo-referenced method for determining available roof area for solar facilities in Spain to produce a quantitative picture of the likely limits of roof-top solar energy. The installation of solar hot water systems (SHWS) and photovoltaic systems (PV) is considered. After satisfying up to 70% (if possible) of the service hot water demand in every municipality, PV systems are installed in the remaining roof area. Results show that, applying this performance-based criterion, SHWS would contribute up to 1662 ktoe/y of primary energy (or 68.5% of the total thermal-energy demand for service hot water), while PV systems would provide 10 T W h/y of electricity (or 4.0% of the total electricity demand). (author)
Izquierdo, Salvador; Montanes, Carlos; Dopazo, Cesar; Fueyo, Norberto [Fluid Mechanics Group, University of Zaragoza and LITEC (CSIC), Maria de Luna 3, 50018 Zaragoza (Spain)
Reconstruction and Supplementary Thermal Insulation of Flat Roofs.
The report describes an experimental and theoretical investigation of a new method involving exterior insulation and closed ventilation gap. In this way both thermal insulation and moisture conditions are improved. The aim of the investigation was to stud...
P. Andersson
Modeling the heat diffusion process in the abiotic layers of green roofs
Green roofs have been increasingly installed to alleviate some common environmental problems. The thermal benefit of living vegetation on rooftop has been extensively studied. The individual and joint contribution of the non-living green roof layers, namely soil, rockwool (water storage) and plastic drainage layers, to thermal performance of green roof has seldom been assessed. This study evaluates the insulating and
C. Y. Jim; S. W. Tsang
Design and Wind Tunnel Performance Testing of a New Omnidirectional Roof Vent
Low-slope roofs are subjected to potentially high levels of suction pressure. Traditional methods of attaching roof membranes to substrates are prone to failure when the low pressure on the roof surface instigates a transfer of forces to the roof membrane. Existing pressure-equalized roof systems use the power of the wind to transmit low pressure to the space immediately beneath the
Elizabeth J. Grant; James R. Jones; Pavlos P. Vlachos
Self drying roofs: What! No dripping!
Many roofs are replaced because water accumulates in portions of the roofing system.These accumulations can cause dripping, accelerated membrane failure, poor thermal performance, the threat of structural decay, and the depreciation of building assets. Traditionally, the roofing industry has been concerned with controlling the inflow of water into the roof. An example of this strategy would be the development of a more reliable membrane. However, roof membranes inevitably leak. For this reason, the roof design strategy of the future must be concerned with controlling water outflow. The requirements of this type of roof system are described. Under normal operating conditions (no leaks), the total moisture content of a self-drying roof system shall not increase with time and condensation shall not occur under the membrane during winter uptake. Moisture vapor movement by convection must be eliminated and the flow of water by gravity through imperfections in the roof system must be controlled. After a leak has occurred, no condensation on the upper surface of the deck shall be tolerated and the water introduced by the leak must be dissipated to the building interior in a minimum amount of time. Finite difference computer modeling is used to demonstrate the effectiveness of the design. The impact of deck and insulation permeance, climate, leaks, and wintertime water uptake are simulated. A database of simulations is qualitatively described; this database will be used in future work to produce a simplified means of assessing the design parameters of a self-drying roof system.
Desjarlais, A.
Advanced Energy Efficient Roof System
Energy consumption in buildings represents 40 percent of primary U.S. energy consumption, split almost equally between residential (22%) and commercial (18%) buildings.1 Space heating (31%) and cooling (12%) account for approximately 9 quadrillion Btu. Improvements in the building envelope can have a significant impact on reducing energy consumption. Thermal losses (or gains) from the roof make up 14 percent of the building component energy load. Infiltration through the building envelope, including the roof, accounts for an additional 28 percent of the heating loads and 16 percent of the cooling loads. These figures provide a strong incentive to develop and implement more energy efficient roof systems. The roof is perhaps the most challenging component of the building envelope to change for many reasons. The engineered roof truss, which has been around since 1956, is relatively low cost and is the industry standard. The roof has multiple functions. A typical wood frame home lasts a long time. Building codes vary across the country. Customer and trade acceptance of new building products and materials may impede market penetration. The energy savings of a new roof system must be balanced with other requirements such as first and life-cycle costs, durability, appearance, and ease of construction. Conventional residential roof construction utilizes closely spaced roof trusses supporting a layer of sheathing and roofing materials. Gypsum board is typically attached to the lower chord of the trusses forming the finished ceiling for the occupied space. Often in warmer climates, the HVAC system and ducts are placed in the unconditioned and otherwise unusable attic. High temperature differentials and leaky ducts result in thermal losses. Penetrations through the ceilings are notoriously difficult to seal and lead to moisture and air infiltration. These issues all contribute to greater energy use and have led builders to consider construction of a conditioned attic. The options considered to date are not ideal. One approach is to insulate between the trusses at the roof plane. The construction process is time consuming and costs more than conventional attic construction. Moreover, the problems of air infiltration and thermal bridges across the insulation remain. Another approach is to use structurally insulated panels (SIPs), but conventional SIPs are unlikely to be the ultimate solution because an additional underlying support structure is required except for short spans. In addition, wood spline and metal locking joints can result in thermal bridges and gaps in the foam. This study undertook a more innovative approach to roof construction. The goal was to design and evaluate a modular energy efficient panelized roof system with the following attributes: (1) a conditioned and clear attic space for HVAC equipment and additional finished area in the attic; (2) manufactured panels that provide structure, insulation, and accommodate a variety of roofing materials; (3) panels that require support only at the ends; (4) optimal energy performance by minimizing thermal bridging and air infiltration; (5) minimal risk of moisture problems; (6) minimum 50-year life; (7) applicable to a range of house styles, climates and conditions; (8) easy erection in the field; (9) the option to incorporate factory-installed solar systems into the panel; and (10) lowest possible cost. A nationwide market study shows there is a defined market opportunity for such a panelized roof system with production and semi-custom builders in the United States. Senior personnel at top builders expressed interest in the performance attributes and indicate long-term opportunity exists if the system can deliver a clear value proposition. Specifically, builders are interested in (1) reducing construction cycle time (cost) and (2) offering increased energy efficiency to the homebuyer. Additional living space under the roof panels is another low-cost asset identified as part of the study. The market potential is enhanced through construction activity levels in target marke
Jane Davidson
Roof System EPDM Shrinkage.
Looks at Ethylene Propylene Diene Terpolymer rubber roof membranes and the potential problems associated with this material's shrinkage. Discusses how long such a roof should perform and issues affecting repair or replacement. Recommends that a building's function be considered in any roofing decision. (RJM)
Betker, Edward
Roof pond systems
This report provides a single-source document useful to architects, engineers, builders, and homeowners that addresses numerous aspects of roof pond design, construction, and performance. An introduction to the roof pond passive solar space heating and cooling concept is provided, including basic methods of operation and system configurations adaptable to different climates. A brief history of the development of the roof pond concept is presented, and several existing roof pond buildings located throughout the United States are described. The regional applicability of roof ponds in both heating and cooling service; design considerations relating to architecture, heating and cooling aspects, and structural requirements; and current heat transfer relations important in roof pond design are examined. A chapter on roof pond system materials and components is included. It contains tables of material properties; descriptions of available and installed components; installation, operation, and maintenance concerns; and a compilation of operating experience to date. The results of actual performance testing of several instrumented roof pond buildings are presented, and in certain cases, these results are compared with roof pond performance simulation results. A life-cycle cost study of two roof pond homes is developed, and the results are compared with the life-cycle costs of two similar conventional residences. This document has application to many related roof pond concepts, such as the Cool Pool and Energy Roof. An extensive bibliography is provided.
Marlatt, W.P.; Murray, K.A.; Squier, S.E.
This paper describes numerical and experimental analysis of a novel design concept. Traditionally the thermal design of building envelope assemblies is based on a static energy flow. However, building envelopes are subject to varying environmental conditions. This mismatch between the steady-state principles used in the design of roofs and walls and their dynamic operation results in relatively low thermal efficiency. Design work in support of the development of zero energy houses showed that conventional insulations may not be the most cost effective energy solution. Testing conducted on several strategies to thermally-disconnect wall and roof components showed 70% to 90% reductions in peak hour loads as compared to conventional building practice.
Miller, William A [ORNL; Kosny, Jan [ORNL; Zaltash, Abdolreza [ORNL
Thermal Environments and Performance.
Although several reviews of thermal influences on performance have appeared during the past decade, none have succeeded in synthesizing the various experimental results. In the meantime, new evidence has been presented from several studies, particularly t...
A. Auliciems
Extracting Roof Parameters and Heat Bridges Over the City of Oldenburg from Hyperspectral, Thermal, and Airborne Laser Scanning Data
Remote sensing methods are used to obtain different kinds of information about the state of the environment. Within the cooperative research project HiReSens, funded by the German BMBF, a hyperspectral scanner, an airborne laser scanner, a thermal camera, and a RGB-camera are employed on a small aircraft to determine roof material parameters and heat bridges of house tops over the city Oldenburg, Lower Saxony. HiReSens aims to combine various geometrical highly resolved data in order to achieve relevant evidence about the state of the city buildings. Thermal data are used to obtain the energy distribution of single buildings. The use of hyperspectral data yields information about material consistence of roofs. From airborne laser scanning data (ALS) digital surface models are inferred. They build the basis to locate the best orientations for solar panels of the city buildings. The combination of the different data sets offers the opportunity to capitalize synergies between differently working systems. Central goals are the development of tools for the collection of heat bridges by means of thermal data, spectral collection of roofs parameters on basis of hyperspectral data as well as 3D-capture of buildings from airborne lasers scanner data. Collecting, analyzing and merging of the data are not trivial especially not when the resolution and accuracy is aimed in the domain of a few decimetre. The results achieved need to be regarded as preliminary. Further investigations are still required to prove the accuracy in detail.
Bannehr, L.; Luhmann, Th.; Piechel, J.; Roelfs, T.; Schmidt, An.
Cycle graph analysis for 3D roof structure modelling: Concepts and performance
The paper presents a cycle graph analysis approach to the automatic reconstruction of 3D roof models from airborne laser scanner data. The nature of convergences of topological relations of plane adjacencies, allowing for the reconstruction of roof corner geometries with preserved topology, can be derived from cycles in roof topology graphs. The topology between roof adjacencies is defined in terms of ridge-lines and step-edges. In the proposed method, the input point cloud is first segmented and roof topology is derived while extracting roof planes from identified non-terrain segments. Orientation and placement regularities are applied on weakly defined edges using a piecewise regularization approach prior to the reconstruction, which assists in preserving symmetries in building geometry. Roof corners are geometrically modelled using the shortest closed cycles and the outermost cycle derived from roof topology graph in which external target graphs are no longer required. Based on test results, we show that the proposed approach can handle complexities with nearly 90% of the detected roof faces reconstructed correctly. The approach allows complex height jumps and various types of building roofs to be firmly reconstructed without prior knowledge of primitive building types.
Perera, Gamage Sanka Nirodha; Maas, Hans-Gerd
Comparison of transient performance predictions of a solar-operated diffusion-type still with a roof-type still
A new type of solar-operated diffusion still is proposed. The still is powered directly by solar radiation and is easy to operate and maintain. Analyses of the proposed diffusion still and the conventional roof-type still are carried out to predict the transient performance of both stills at various operating and design conditions. Comparison of the performance of both stills on four sample days through the year is considered. The comparison shows that, although the diffusion still has a higher cover temperature, (i.e., larger heat loss to ambient) than the roof-type still, the diffusion still is superior to the roof-type still in both production rate and operation efficiency. The results also show that an increase in ambient temperature improves the performance of both stills.
Elsayed, M.M.
Effectiveness of Cool Roof Coatings with Ceramic Particles
Liquid applied coatings promoted as cool roof coatings, including several with ceramic particles, were tested at Oak Ridge National Laboratory (ORNL), Oak Ridge, Tenn., for the purpose of quantifying their thermal performances. Solar reflectance measurements were made for new samples and aged samples using a portable reflectometer (ASTM C1549, Standard Test Method for Determination of Solar Reflectance Near Ambient Temperature Using a Portable Solar Reflectometer) and for new samples using the integrating spheres method (ASTM E903, Standard Test Method for Solar Absorptance, Reflectance, and Transmittance of Materials Using Integrating Spheres). Thermal emittance was measured for the new samples using a portable emissometer (ASTM C1371, Standard Test Method for Determination of Emittance of Materials Near Room 1 Proceedings of the 2011 International Roofing Symposium Temperature Using Portable Emissometers). Thermal conductivity of the coatings was measured using a FOX 304 heat flow meter (ASTM C518, Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus). The surface properties of the cool roof coatings had higher solar reflectance than the reference black and white material, but there were no significant differences among coatings with and without ceramics. The coatings were applied to EPDM (ethylene propylene diene monomer) membranes and installed on the Roof Thermal Research Apparatus (RTRA), an instrumented facility at ORNL for testing roofs. Roof temperatures and heat flux through the roof were obtained for a year of exposure in east Tennessee. The field tests showed significant reduction in cooling required compared with the black reference roof (~80 percent) and a modest reduction in cooling compared with the white reference roof (~33 percent). The coating material with the highest solar reflectivity (no ceramic particles) demonstrated the best overall thermal performance (combination of reducing the cooling load cost and not incurring a large heating penalty cost) and suggests solar reflectivity is the significant characteristic for selecting cool roof coatings.
Brehob, Ellen G [ORNL; Desjarlais, Andre Omer [ORNL; Atchley, Jerald Allen [ORNL
Performance of 3sun mirror modules on sun tracking carousels on flat roof buildings
Commercial buildings represent a near term market for cost competitive solar electric power provided installation costs and solar photovoltaic module costs can be reduced. JX Crystals has developed a carousel sun tracker that is prefabricated and can easily be deployed on building flat roof tops without roof penetration. JX Crystals is also developing 3-sun PV mirror modules where less expensive
Lewis Fraas; James E. Avery; Leonid M Minkin; Curt Maxey; Tony Gehl; Rick A Hurt; Robert F Boehm
Wind dynamics, on a conventional roofing system, lift the membrane and cause fluttering, introducing stresses at the attachment locations. To identify the component of the system that has the weakest resistance against wind uplift forces, a dynamic method of evaluating roofing systems is beneficial. A vapour barrier is defined as a material of low permeance, which limits moisture transport through
Built-Up Roof Construction Quality Control.
This report recommends ways to improve the performance of built-up roofing in Army facilities by advancing roof construction quality control and quality assurance. This study assessed the state of the art in roofing quality control; evaluated existing Arm...
E. S. Lindow E. Marvin M. J. Rosenfield J. Blair
Roof Roundup.
The roof management program at the University of Wyoming involved a consulting firm that provided a computer analysis of the condition of each roof on campus and trained university personnel to act as inspectors in the future. (MLF)
American School and University, 1984
Evaporative roof cooling system
An evaporative roof cooling system is described for placement upon a roof surface exposed to relatively high levels of solar radiation causing high under roof temperatures and comprising: (a) water distribution mist/spray nozzles positioned on the roof surface for supplying substantially uniform mist/sprays of water to lay down a substantially uniform thin film of water on the roof surface; (b) conduit means on the one roof surface for supplying the nozzles with water; (c) solenoid-controlled valve means in water flow communication with the conduit means to supply controlled quantities of water to the nozzles through the conduit means over periods during which the temperature of the roof surface is measured to be within a predetermined temperature range; (d) temperature measurement means comprised of a thermistor encapsulated in an epoxy block in direct contact with the roof surface for monitoring and measuring the actual temperature of the surface substantially by thermal conductivity and developing an electrical resistance value in direct relationship with the temperature of the surface; and (e) cooling system control means in electric communication with the temperature measurement means for comparing the electric resistance value developed by the temperature measurement means and a range of current values related to the predetermined temperature range.
Viner, S.G.
In situ performance assessment of vacuum insulation panels in a flat roof construction
The recently introduced vacuum insulation panel (VIP) is a space saving alternative to conventional thermal insulation, thanks to its five to eight times higher thermal resistivity. As gas permeation through the envelope barrier may drastically reduce the insulation efficiency, aging effects and service life expectation are crucial aspects of those high performance insulation units. In the present paper, monitoring data
Samuel Brunner; Hans Simmler
Roofing: Workbook and Tests. Built-up Roofing.
Designed for use in roofing apprenticeship classes, this workbook contains eight units on skills used in built-up roofing, a listing of instructional materials, a glossary, and the text of Labor Code Article 30, Construction Safety Orders, "Roofing Operations and Equipment." Each instructional unit includes a listing of performance statements and�
Klingensmith, Robert, Ed.
A Dynamic Mathematical Model to Predict the Performance of Passive Cooling System by Evapo-Reflective Roof for Hot Dry Climates
A dynamic mathematical model used to predict the performance of passive cooling system by evapo-reflective roof in buildings for hot arid climates has been developed. The cooling system consists of a roof composed of concrete ceiling and flat aluminium plate, separated with air space partially filled with rocks and small quantity of water. Low emissive aluminium sheet with white painting
H. Bencheikh; A. Bouchair
Thermal Performance Data Services (TPDS)
NASA Technical Reports Server (NTRS)
Initiated as a NASA Engineering and Safety Center (NESC) assessment in 2009, the Thermal Performance Database (TPDB) was a response to the need for a centralized thermal performance data archive. The assessment was renamed Thermal Performance Data Services (TPDS) in 2012; the undertaking has had two fronts of activity: the development of a repository software application and the collection of historical thermal performance data sets from dispersed sources within the thermal performance community. This assessment has delivered a foundational tool on which additional features should be built to increase efficiency, expand the protection of critical Agency investments, and provide new discipline-advancing work opportunities. This report contains the information from the assessment.
French, Richard T.; Wright, Michael J.
The Rehab Guide: Roofs
NSDL National Science Digital Library
Anyone who has been on a roof on a hot day can attest to the difficulty of performing basic maintenance on that particular part of a building. Fortunately, this time-consuming process can be made simpler with this handy online guide to rehabbing a roof. Created by the PATH Group, this 99-page document covers major roofing systems, ��as well as protective strategies, energy and air filtration issues, roofing materials, and gutters and downspouts.� Throughout the document, users can rely on drawings and photographs that illustrate various rehabbing techniques. Much is revealed here, including timely information on low-slope and metal roofing, along with suggestions on installing moisture barriers.
Improved Thermal Battery Performance.
A thermal battery was developed which demonstrated an energy density in excess of 17 watt-hours per pound. This advancement of approximately three times the energy density of thermal batteries was accomplished with the lithium aluminum iron disulfide syst...
J. A. DeGruson
CFD modelling of air flow and thermal performance of an atrium integrated with photovoltaics
The thermal performance of an atrium integrated with photovoltaic (PV) modules has been evaluated. Computational fluid dynamics (CFD) was applied to the prediction of air flow and temperature distribution in the atrium. CFD was then used to investigate the effect of ventilation strategies on the performance of PV arrays. CFD modelling indicated that for effective cooling of roof PV arrays,
Guohui Gan; Saffa B. Riffat
Improved roof stabilization technologies
Decontamination and decommissioning (D and D) activities require that personnel have access to all areas of structures, some of which are more than 40 years old. In many cases, these structures have remained in a standby condition for up to 10 years; few preventative maintenance activities have been performed on them because of lack of funding or a defined future plan of action. This situation has led to deteriorated building conditions, resulting in potential personnel safety hazards. In addition, leaky roofs allow water to enter the buildings, which can cause the spread of contamination and increase building deterioration, worsening the already unsafe working conditions. To ensure worker safety and facilitate building dismantlement, the assessment of roof stabilization techniques applicable to US Department of Energy (DOE) structures has become an important issue. During Fiscal year 1997 (FY97), a comprehensive reliability-based model for the structural stabilization analysis of roof system in complex structures was developed. The model consists of three major components: a material testing method, a deterministic structural computer model, and a reliability-based optimization, and probabilistic analyses of roof structures can be implemented. Given site-specific needs, this model recommends the most appropriate roof stabilization system. This model will give not only an accurate evaluation of the existing roof system in complex structures, but it will also be a reliable method to aid the decision-making process. This final report includes in its appendix a Users` Manual for the Program of Deterministic and Reliability Analysis of Roof Structures.
Ebadian, M.A.
Sustainable roofs with real energy savings
This paper addresses the general concept of sustainability and relates it to the building owner`s selection of a low-slope roof. It offers a list of performance features of sustainable roofs. Experiences and data relevant to these features for four unique roofs are then presented which include: self-drying systems, low total equivalent warming foam insulation, roof coatings and green roofs. The paper concludes with a list of sustainable roofing features worth considering for a low-slope roof investment. Building owners and community developers are showing more interest in investing in sustainability. The potential exists to design, construct, and maintain roofs that last twice as long and reduce the building space heating and cooling energy loads resulting from the roof by 50% (based on the current predominant design of a 10-year life and a single layer of 1 to 2 in. (2.5 to 5.1 cm) of insulation). The opportunity to provide better low-slope roofs and sell more roof maintenance service is escalating. The general trend of outsourcing services could lead to roofing companies` owning the roofs they install while the traditional building owner owns the rest of the building. Such a situation would have a very desirable potential to internalize the costs of poor roof maintenance practices and high roof waste disposal costs, and to offer a profit for installing roofs that are more sustainable. 14 refs., 12 figs.
Christian, J.E.; Petrie, T.W.
Integrated Modelling and Performance Analysis of Green Roof Technologies in Urban Environments
As a result of the changing global climate and increase in urbanisation, the behaviour of the urban environment has been significantly altered, causing an increase in both the frequency of extreme weather events, such as flooding and drought, and also the associated costs. Moreover, uncontrolled or inadequately planned urbanisation can exacerbate the damage. The Blue-Green Dream (BGD) project therefore develops a series of components for urban areas that link urban vegetated areas (green infrastructure) with existing urban water (blue) systems, which will enhance the synergy of urban blue and green systems and provide effective, multifunctional BGD solutions to support urban adaptation to future climatic changes. Coupled with new urban water management technologies and engineering, multifunctional benefits can be gained. Some of the technologies associated with BGD solutions include green roofs, swales that might deal with runoff more effectively and urban river restoration that can produce benefits similar to those produced from sustainable urban drainage systems (SUDS). For effective implementation of these technologies, however, appropriate tools and methodologies for designing and modelling BGD solutions are required to be embedded within urban drainage models. Although several software packages are available for modelling urban drainage, the way in which green roofs and other BGD solutions are integrated into these models is not yet fully developed and documented. This study develops a physically based mass and energy balance model to monitor, test and quantitatively evaluate green roof technology for integrated BGD solutions. The assessment of environmental benefits will be limited to three aspects: (1) reduction of the total runoff volume, (2) delay in the initiation of runoff, and (3) reduction of building energy consumption, rather than water quality, visual, social or economic impacts. This physically based model represents water and heat dynamics in a layered soil profile covered with vegetation which can be used to simulate the physical behaviour of different green roof systems in response to rainfall under various climatic conditions. Because it is a physically based model, this model could be generalised to other atmosphere-plant-soil systems. The validity of this mass and energy balance approach will be demonstrated by comparing its outcomes with observations from a green roof experimental site in London, UK.
Liu, Xi; Mijic, Ana; Maksimovic, Cedo
Bright is the New Black - Multi-Year Performance of Generic High-Albedo Roofs in an Urban Climate
High-albedo white and cool roofing membranes are recognized as a fundamental strategy that dense urban areas can deploy on a large scale, at low cost, to mitigate the urban heat island effect. We are monitoring three generic white membranes within New York City that represent a cross-section of the dominant white membrane options for U.S. flat roofs: (1) an ethylene propylene diene monomer (EPDM) rubber membrane; (2) a thermoplastic polyolefin (TPO) membrane and; (3) an asphaltic multi-ply built-up membrane coated with white elastomeric acrylic paint. The paint product is being used by New York City s government for the first major urban albedo enhancement program in its history. We report on the temperature and related albedo performance of these three membranes at three different sites over a multi-year period. The results indicate that the professionally installed white membranes are maintaining their temperature control effectively and are meeting the Energy Star Cool Roofing performance standards requiring a three-year aged albedo above 0.50. The EPDM membrane however shows evidence of low emissivity. The painted asphaltic surface shows high emissivity but lost about half of its initial albedo within two years after installation. Given that the acrylic approach is an important "do-it-yourself," low-cost, retrofit technique, and, as such, offers the most rapid technique for increasing urban albedo, further product performance research is recommended to identify conditions that optimize its long-term albedo control. Even so, its current multi-year performance still represents a significant albedo enhancement for urban heat island mitigation.
Gaffin, S. R.; Imhoff, M.; Rosenzweig, C.; Khanbilvardi, R.; Pasqualini, A.; Kong, A. Y. Y.; Grillo, D.; Freed, A.; Hillel, D.; Hartung, E.
Roof Plans: Section "CC", Roof Plan; Roof Framing Plans: Section ...
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
Roof Plans: Section "C-C", Roof Plan; Roof Framing Plans: Section "C-C", Section "D-D"; Roof Framing Sections: Cross Section "G-G", Cross Section "H-H" - Fort Washington, Fort Washington Light, Northeast side of Potomac River at Fort Washington Park, Fort Washington, Prince George's County, MD
Performance of thermal envelope houses
The performance of a hypothetical thermal envelope house is evaluated based on the results of a year-long thermal network simulation. The house has a floor area of 1500 ft² (139 m²) and 360 ft² (33.5 m²) south-facing double glazing, half vertical and half at a 45° tilt. The above grade inner and outer envelope walls have nominal resistances of R-11
J. Kohler; D. Lewis
Experts look at thermal performance
Energy-management experts answer questions on the performance and effectiveness of thermal insulation. They offer suggestions on determining how much and which kind of insulation to use, the effectiveness of energy-efficiency standards, the information obtained from research programs, and continuing research needs. Convincing management that insulation will be cost-effective continues to be a significant barrier. (DCK)
Lawn, J.
Guidelines for Inspecting Your Roof Systems.
Provides guidelines for inspecting the roof of a facility. Suggests that periodic roof inspections should be performed on a quarterly or semi-annual basis and after severe storms. Proactively identifying potential problem areas is the best defense against roof leaks. (SLD)
Watkins, Daniel L.
Hydrological performance of extensive green roofs in New York City: observations and multi-year modeling of three full-scale systems
Green roofs can be an attractive strategy for adding perviousness in dense urban environments where rooftops are a high fraction of the impervious land area. As a result, green roofs are being increasingly implemented as part of urban stormwater management plans in cities around the world. In this study, three full-scale green roofs in New York City (NYC) were monitored, representing the three extensive green roof types most commonly constructed: (1) a vegetated mat system installed on a Columbia University residential building, referred to as W118; (2) a built-in-place system installed on the United States Postal Service (USPS) Morgan general mail facility; and (3) a modular tray system installed on the ConEdison (ConEd) Learning Center. Continuous rainfall and runoff data were collected from each green roof between June 2011 and June 2012, resulting in 243 storm events suitable for analysis ranging from 0.25 to 180 mm in depth. Over the monitoring period the W118, USPS, and ConEd roofs retained 36%, 47%, and 61% of the total rainfall respectively. Rainfall attenuation of individual storm events ranged from 3 to 100% for W118, 9 to 100% for USPS, and 20 to 100% for ConEd, where, generally, as total rainfall increased the per cent of rainfall attenuation decreased. Seasonal retention behavior also displayed event size dependence. For events of 10-40 mm rainfall depth, median retention was highest in the summer and lowest in the winter, whereas median retention for events of 0-10 mm and 40 +mm rainfall depth did not conform to this expectation. Given the significant influence of event size on attenuation, the total per cent retention during a given monitoring period might not be indicative of annual rooftop retention if the distribution of observed event sizes varies from characteristic annual rainfall. To account for this, the 12 months of monitoring data were used to develop a characteristic runoff equation (CRE), relating runoff depth and event size, for each green roof. When applied to Central Park, NYC precipitation records from 1971 to 2010, the CRE models estimated total rainfall retention over the 40 year period to be 45%, 53%, and 58% for the W118, USPS, and ConEd green roofs respectively. Differences between the observed and modeled rainfall retention for W118 and USPS were primarily due to an abnormally high frequency of large events, 50 mm of rainfall or more, during the monitoring period compared to historic precipitation patterns. The multi-year retention rates are a more reliable estimate of annual rainfall capture and highlight the importance of long-term evaluations when reporting green roof performance.
Carson, T. B.; Marasco, D. E.; Culligan, P. J.; McGillis, W. R.
An evaporative roof cooling system is described for placement upon a roof surface exposed to relatively high levels of solar radiation causing high under roof temperatures and comprising: (a) water distribution mist\\/spray nozzles positioned on the roof surface for supplying substantially uniform mist\\/sprays of water to lay down a substantially uniform thin film of water on the roof surface; (b)
Understanding Roofing Systems.
Reviews the various types of multi- and single-ply roofing commonly used today in educational facilities. Roofing types described involve built-up systems, modified bitumen systems; ethylene propylene diene terpolymer roofs; and roofs of thermoplastic, metal, and foam. A description of the Roofing Industry Educational Institute is included. (GR)
Michelsen, Ted
Guide for Airborne Infrared Roof Moisture Surveys.
This report presents guidance for the conduct of aerial roof moisture surveys using thermal infrared (IR) scanner systems. Specific information is presented concerning assembly of relevant data prior to the thermal IR imagery acquisition, planning the ima...
L. E. Link
Experimental polyurethane foam roof systems - II. Technical note Oct 75-Jul 81
An experimental roofing installation is described in which polyurethane foam (PUF) was spray-applied directly to metal Butlerib-type metal decks, the roof divided into five approximately equal areas, and the PUF protected with five different elastomeric coating systems. Three of the coating systems were damaged by hailstones about a year after installation; these systems were recoated within 3 years of the initial installation. The current coatings include two of the original coating systems - a plural component silicone and a single component silicone - and those applied over the three systems damaged by hail - a single component silicone, an aluminum filled, hydrocarbon-extended catalyzed urethane, and a catalyzed urethane. The performance of these five PUF systems over a 7-year period is reported. The temperature distributions throughout the roof systems are described. The decay in the thermal conductivity of the PUF roof over a 5-year period is presented, and the energy savings realized by foaming the roof are presented.
Alumbaugh, R.L.; Keeton, J.R.; Humm, E.F.
Use of roof temperature modeling to predict necessary conditions for locating wet insulation with infrared thermography
In low-sloped roofing systems using porous insulation, the presence of water can significantly degrade thermal performance. For this reason, it is desirable to develop a reliable method for detecting the presence of water in a roofing system. Because of the different thermal characteristics of wet and dry insulation, there is often a surface temperature differential between areas containing wet insulation and areas containing dry insulation. Under the right circumstances, the areas of wet insulation can be detected by means of infrared sensing techniques. These techniques have already gained widespread acceptance, but there is still some uncertainty as to what are appropriate environmental conditions for viewing. To better define the conditions under which infrared techniques can distinguish between areas of wet and dry insulation, a one-dimensional, transient heat transfer model of a roofing system was developed. The model considers conduction through the roof, insolation on the surface, radiant exchange between the roof and sky, convective heat transfer between the roof and air, and the influence of trapped moisture on the thermal properties of the insulation. A study was undertaken using this model to develop an easily-applied technique for prediction of necessary conditions for locating wet roof insulation using infrared thermography.
Childs, K.W.
Performance of a solar dryer using hot air from roof-integrated solar collectors for drying herbs and spices
A solar dryer for drying herbs and spices using hot air from roof-integrated solar collectors was developed. The dryer is a bin type with a rectangular perforated floor. The bin has a dimension of 1.0m�2.0m�0.7m. Hot air is supplied to the dryer from fiberglass-covered solar collectors, which also function as the roof of a farmhouse. The total area of the
S. Janjai; P. Tung
Radiation control coatings installed on rough-surfaced built-up roofs -- Initial results
The authors have tracked the solar reflectance and thermal performance of small samples of various radiation control coatings on smooth surfaces for several years on a roof test facility in East Tennessee. The focus is on white coatings because of their potential to weather, causing the solar reflectance to decrease as the coatings age. Support of the federal New Technology Demonstration Program allowed them to extend the study to more samples on smooth surfaces and entire rough-surfaced roofs at a federal facility in the Panhandle of Florida. Two rough-surfaced, moderately well-insulated, low solar reflectance built-up roofs (BURs) were spray-coated with a latex-based product with ceramic beads added to improve solar reflectance. In the first three months after installation, the fresh BUR coatings showed a significant decrease in both the outside-surface temperature and the heat flux through the roof insulation. Average sunlit values were generated to exclude nighttime data, data on cloudy days, and data when the uncoated patch on one roof was more strongly shaded in mid-afternoon on sunny days. The average power demand during occupied periods for the first month with the coating for the building with the thermally massive roof deck was 13% less than during the previous month without the coating. For the other buildings with a lightweight roof deck but high internal loads, there were no clear average power savings due to the coating. The authors are continuing to monitor electricity use in these all-electric buildings to calibrate a model for the peak power and annual energy use of the buildings. Modeling results to be given at the end of the two year project will address the effect of roof R-value, geographic location, and solar reflectance, including the effect of weathering, on the performance of coated roofs. The calibrated models should allow one to segregate site-specific effects such as shading and large thermal mass.
Petrie, T.W.; Childs, P.W.; Christian, J.E.
Occupant dynamics in rollover crashes: influence of roof deformation and seat belt performance on probable spinal column injury.
Motor vehicle crashes are the leading cause of death in the United States for people ages 3-33, and rollover crashes have a higher fatality rate than any other crash mode. At the request and under the sponsorship of Ford Motor Company, Autoliv conducted a series of dynamic rollover tests on Ford Explorer sport utility vehicles (SUV) during 1998 and 1999. Data from those tests were made available to the public and were analyzed in this study to investigate the magnitude of and the temporal relationship between roof deformation, lap-shoulder seat belt loads, and restrained anthropometric test dummy (ATD) neck loads. During each of the three FMVSS 208 dolly rollover tests of Ford Explorer SUVs, the far-side, passenger ATDs exhibited peak neck compression and flexion loads, which indicated a probable spinal column injury in all three tests. In those same tests, the near-side, driver ATD neck loads never predicted a potential injury. In all three tests, objective roof/pillar deformation occurred prior to the occurrence of peak neck loads (F ( z ), M ( y )) for far-side, passenger ATDs, and peak neck loads were predictive of probable spinal column injury. The production lap and shoulder seat belts in the SUVs, which restrained both driver and passenger ATDs, consistently allowed ATD head contact with the roof while the roof was contacting the ground during this 1000 ms test series. Local peak neck forces and moments were noted each time the far-side, passenger ATD head contacted ("dived into") the roof while the roof was in contact with the ground; however, the magnitude of these local peaks was only 2-13% of peak neck loads in all three tests. "Diving-type" neck loads were not predictive of injury for either driver or passenger ATD in any of the three tests. PMID:17641975
Bidez, Martha W; Cochran, John E; King, Dottie; Burke, Donald S
Thermal Hydraulic Performance of Tight Lattice Bundle
Recently, the reduced moderation spectrum BWR has been studied. The fast neutron spectrum is obtained through triangular tight lattice fuel. However, there are few thermal hydraulic test data and thermal hydraulic correlation applicable to critical power prediction in such a tight lattice bundle. This study aims to enhance the database of the thermal hydraulic performance of the tight lattice bundle whose rod gap is about 1mm. Therefore, thermal hydraulic performance measurement tests of tight lattice bundles for the critical power, the pressure drop and the counter current flow limiting were performed. Moreover, the correlations to evaluate the thermal-hydraulic performance of the tight lattice bundle were developed.
Yamamoto, Yasushi; Akiba, Miyuki; Morooka, Shinichi; Shirakawa, Kenetsu; Abe, Nobuaki
Strategies for encouraging miners to stay away from unsupported roof and perform self-protective actions. Information Circular\\/1991
Groundfall accidents have been the leading cause of fatalities in the underground coal mining industry for many years. Statistics from the Mine Safety and Health Administration (MSHA) indicate that approximately half of the victims of these fatal accidents were in an area where no devices had been installed to support the mine roof. The report was prepared by the U.S.
Bright is the New Black - Multi-Year Performance of Generic High-Albedo Roofs in an Urban Climate.
High-albedo white and cool roofing membranes are recognized as a fundamental strategy that dense urban areas can deploy on a large scale, at low cost, to mitigate the urban heat island effect. We are monitoring three generic white membranes within New Yor...
A. Freed A. Pasqualini A. Y. Y. Kong C. Rosenzweig D. Grillo D. Hillel E. Hartung M. Imhoff R. Khanbilvardi S. R. Gaffin
Recently, the reduced moderation spectrum BWR has been studied. The fast neutron spectrum is obtained through triangular tight lattice fuel. However, there are few thermal hydraulic test data and thermal hydraulic correlation applicable to critical power prediction in such a tight lattice bundle. This study aims to enhance the database of the thermal hydraulic performance of the tight lattice bundle
Yasushi Yamamoto; Miyuki Akiba; Shinichi Morooka; Kenetsu Shirakawa; Nobuaki Abe
Inclusion of cool roofs in nonresidential Title 24 prescriptive requirements
Roofs that have high solar reflectance (high ability to reflect sunlight) and high thermal emittance (high ability to radiate heat) tend to stay cool in the sun. The same is true of low-emittance roofs with exceptionally high solar reflectance. Substituting a cool roof for a noncool roof tends to decrease cooling electricity use, cooling power demand, and cooling-equipment capacity requirements, while slightly increasing heating energy consumption. Cool roofs can also lower the ambient air temperature in summer, slowing ozone formation and increasing human comfort. DOE-2.1E building energy simulations indicate that use of a cool roofing material on a prototypical California nonresidential building with a low-sloped roof yields average annual cooling energy savings of approximately 300 kWh/1000 ft2 [3.2 kWh/m2], average annual natural gas deficits of 4.9 therm/1000 ft2 [5.6 MJ/m2], average source energy savings of 2.6 MBTU/1000 ft2 [30 MJ/m2], and average peak power demand savings of 0. 19 kW/1000 ft2 [2.1 W/m2]. The 15-year net present value (NPV) of energy savings averages $450/1000 ft2 [$4.90/m2] with time dependent valuation (TDV), and $370/1000 ft2 [$4.00/m2] without TDV. When cost savings from downsizing cooling equipment are included, the average total savings (15-year NPV + equipment savings) rises to $550/1000 ft2 [$5.90/m2] with TDV, and to $470/1000 ft2 [$5.00/m2] without TDV. Total savings range from 0.18 to 0.77 $/ft2 [1.90 to 8.30 $/m2] with TDV, and from 0.16 to 0.66 $/ft2 [1.70 to 7.10 $/m2] without TDV, across California's 16 climate zones. The typical cost premium for a cool roof is 0.00 to 0.20 $/ft2 [0.00 to 2.20 $/m2]. Cool roofs with premiums up to $0.20/ft2 [$2.20/m2] are expected to be cost effective in climate zones 2 through 16; those with premiums not exceeding $0.18/ft2 [$1.90/m2] are expected to be also cost effective in climate zone 1. Hence, this study recommends that the year-2005 California building energy efficiency code (Title 24, Pa rt 6 of the California Code of Regulations) for nonresidential buildings with low-sloped roofs include a cool-roof prescriptive requirement in all California climate zones. Buildings with roofs that do not meet prescriptive requirements may comply with the code via an ''overall-envelope'' approach (non-metal roofs only), or via a performance approach (all roof types).
Levinson, Ronnen; Akbari, Hashem; Konopacki, Steve; Bretz, Sarah
Thermal and other tests of photovoltaic modules performed in natural sunlight
The nominal operating cell temperature (NOCT), an effective way to characterize the thermal performance of a photovoltaic module in natural sunlight, is developed. NOCT measurements for more than twenty different modules are presented. Changes in NOCT reflect changes in module design, residential roof mounting, and dirt accumulation. Other test results show that electrical performance is improved by cooling modules with water and by use of a phase change wax. Electrical degradation resulting from the marriage of photovoltaic and solar water heating modules is demonstrated. Cost-effectiveness of each of these techniques is evaluated.
Stultz, J. W.
Photovoltaic roof construction
In a batten-seam roof construction employing at least one photovoltaic cell module, the electrical conduits employed with the at least one photovoltaic cell module are disposed primarily under the battens of the roof.
Impact of Sustainable Cool Roof Technology on Building Energy Consumption
Highly reflective roofing systems have been analyzed over several decades to evaluate their ability to meet sustainability goals, including reducing building energy consumption and mitigating the urban heat island. Studies have isolated and evaluated the effects of climate, surface reflectivity, and roof insulation on energy savings, thermal load mitigation and also ameliorating the urban heat island. Other sustainable roofing systems, like green-roofs and solar panels have been similarly evaluated. The motivation for the present study is twofold: the first goal is to present a method for simultaneous evaluation and inter-comparison of multiple roofing systems, and the second goal is to quantitatively evaluate the realized heating and cooling energy savings associated with a white roof system compared to the reduction in roof-top heat flux. To address the first research goal a field experiment was conducted at the International Harvester Building located in Portland, OR. Thermal data was collected for a white roof, vegetated roof, and a solar panel shaded vegetated roof, and the heat flux through these roofing systems was compared against a control patch of conventional dark roof membrane. The second research goal was accomplished using a building energy simulation program to determine the impact of roof area and roof insulation on the savings from a white roof, in both Portland and Phoenix. The ratio of cooling energy savings to roof heat flux reduction from replacing a dark roof with a white roof was 1:4 for the month of July, and 1:5 annually in Portland. The COP of the associated chillers ranges from 2.8-4.2, indicating that the ratio of cooling energy savings to heat flux reduction is not accounted for solely by the COP of the chillers. The results of the building simulation indicate that based on energy savings alone, white roofs are not an optimal choice for Portland. The benefits associated with cooling energy savings relative to a black roof are offset by the winter-time penalty, and the net benefit from adopting white roof technology in Portland is small. That said, there are other potential benefits of white roofing such as impact on urban heat islands and roof life that must also be considered.
Vuppuluri, Prem Kiran
Comparative studies on different type of roof ponds for cooling purposes: litera- ture review
Bioclimatic approach gives attention to the design of roof since it is commonly the building element which is most exposed. Some of the most favorable roof cool- ing techniques are roof ponds which appear to influence the thermal behavior of roof through different processes including evaporation, radiation and conduction. Large air-conditioning energy savings were estimated, reach- ing 100% in a
A. Spanaki
Which Roof is Tops?
When you walk or drive around your neighborhood what do the roofs look like? What if you lived in an area with a different climate, how would that effect the style of roof that you might find. This is an introductory activity to explore the advantages of different roof shapes for different climates or situations.
Center For Engineering Educational Outreach
Selecting a Roof Membrane.
Offers a brief synopsis of the unique characteristics of the following roof membranes: (1) built-up roofing; (2) elastoplastic membranes; (3) modified bitumen membranes; (4) liquid applied membranes; and (5) metal roofing. A chart compares the characteristics of the raw membranes only. (MLF)
Waldron, Larry W.
Green roof systems: a study of public attitudes and preferences in southern Spain.
This study investigates people's preconceptions of green roofs and their visual preference for different green roof design alternatives in relation to behavioral, social and demographical variables. The investigation was performed as a visual preference study using digital images created to represent eight different alternatives: gravel roof, extensive green roof with Sedums not in flower, extensive green roof with sedums in bloom, semi-intensive green roof with sedums and ornamental grasses, semi-intensive green roof with shrubs, intensive green roof planted with a lawn, intensive green roof with succulent and trees and intensive green roof with shrubs and trees. Using a Likert-type scale, 450 respondents were asked to indicate their preference for each digital image. Results indicated that respondents' sociodemographic characteristics and childhood environmental background influenced their preferences toward different green roof types. Results also showed that green roofs with a more careful design, greater variety of vegetation structure, and more variety of colors were preferred over alternatives. PMID:23722180
Fernandez-Ca�ero, Rafael; Emilsson, Tobias; Fernandez-Barba, Carolina; Herrera Machuca, Miguel �ngel
Evolution of cool-roof standards in the United States
Roofs that have high solar reflectance and high thermal emittance stay cool in the sun. A roof with lower thermal emittance but exceptionally high solar reflectance can also stay cool in the sun. Substituting a cool roof for a noncool roof decreases cooling-electricity use, cooling-power demand, and cooling-equipment capacity requirements, while slightly increasing heating-energy consumption. Cool roofs can also lower citywide ambient air temperature in summer, slowing ozone formation and increasing human comfort. Provisions for cool roofs in energy-efficiency standards can promote the building- and climate-appropriate use of cool roofing technologies. Cool-roof requirements are designed to reduce building energy use, while energy-neutral cool-roof credits permit the use of less energy-efficient components (e.g., larger windows) in a building that has energy-saving cool roofs. Both types of measures can reduce the life-cycle cost of a building (initial cost plus lifetime energy cost). Since 1999, several widely used building energy-efficiency standards, including ASHRAE 90.1, ASHRAE 90.2, the International Energy Conservation Code, and California's Title 24 have adopted cool-roof credits or requirements. This paper reviews the technical development of cool-roof provisions in the ASHRAE 90.1, ASHRAE 90.2, and California Title 24 standards, and discusses the treatment of cool roofs in other standards and energy-efficiency programs. The techniques used to develop the ASHRAE and Title 24 cool-roof provisions can be used as models to address cool roofs in building energy-efficiency standards worldwide.
Akbari, Hashem; Akbari, Hashem; Levinson, Ronnen
This paper presents a systematic decision-making approach for roofing maintenance management that combines a stochastic Markovian performance prediction model with a multi-objective optimization method to determine the optimal allocation of funds and prioritization of roofs for maintenance, repair and replacement. A product model of the roof system is used to provide the data framework for collecting and processing data. The
Zoubir Lounis; Brian Kyle
Variation in thermal performance among insect populations.
Among-population variation in insect thermal performance is important for understanding patterns and mechanisms of evolution and predicting insect responses to altered climate regimes in future or novel environments. Here we review and discuss several key examples of among-population variation in insect thermal performance, including latitudinal gradients in chill coma recovery time, variation in energy consumption and metabolic biochemistry, rapid changes in thermal biology with range expansion in invasive and introduced species, and potential constraints on variation in thermal performance traits. This review highlights that while there is substantial evidence for among-population variation that is generally correlated with local climate regimes, neither the underlying mechanisms nor the implications for whole-animal fitness in the field are well understood. We also discuss the potential limitations of interpreting evolved variation among populations and argue for a genes-to-environment approach to population-level variation in thermal biology of insects. PMID:23099457
Sinclair, Brent J; Williams, Caroline M; Terblanche, John S
Work Performance Under Thermal Stress.
This is a report on some of the recent and current work in the environmental chamber at Texas Tech University. Specific studies discussed include: an investigation of variable temperature and diet effects on monitoring performance; an analysis of effects ...
A. Mortagy, J. D. Ramsey
Thermal performance and heat transport in aquifer thermal energy storage
Aquifer thermal energy storage (ATES) is used for seasonal storage of large quantities of thermal energy. Due to the increasing demand for sustainable energy, the number of ATES systems has increased rapidly, which has raised questions on the effect of ATES systems on their surroundings as well as their thermal performance. Furthermore, the increasing density of systems generates concern regarding thermal interference between the wells of one system and between neighboring systems. An assessment is made of (1) the thermal storage performance, and (2) the heat transport around the wells of an existing ATES system in the Netherlands. Reconstruction of flow rates and injection and extraction temperatures from hourly logs of operational data from 2005 to 2012 show that the average thermal recovery is 82 % for cold storage and 68 % for heat storage. Subsurface heat transport is monitored using distributed temperature sensing. Although the measurements reveal unequal distribution of flow rate over different parts of the well screen and preferential flow due to aquifer heterogeneity, sufficient well spacing has avoided thermal interference. However, oversizing of well spacing may limit the number of systems that can be realized in an area and lower the potential of ATES.
Sommer, W. T.; Doornenbal, P. J.; Drijver, B. C.; van Gaans, P. F. M.; Leusbrock, I.; Grotenhuis, J. T. C.; Rijnaarts, H. H. M.
Radiation control coatings installed on rough-surfaced built-up roofs -- Initial results.
The authors have tracked the solar reflectance and thermal performance of small samples of various radiation control coatings on smooth surfaces for several years on a roof test facility in East Tennessee. The focus is on white coatings because of their p...
T. W. Petrie P. W. Childs J. E. Christian
Performance analysis of solar thermal power systems
Methods of analyzing and predicting the performance of solar thermal power plants for electric applications are discussed, and insight provided into the major energy loss mechanisms for solar thermal systems. The efficiency of each component in a solar thermal plant is discussed as are the plant parasitic losses and plant availability. This is followed by a discussion of the computer simulation which is needed to derive reasonable projections of component annual efficiencies and parasitic losses. Finally, plant design considerations and annual system performance estimates are made.
Williams, T. A.; Dirks, J. A.
Theoretical analysis to investigate thermal performance of co-axial heat pipe solar collector
The thermal performance of co-axial heat pipe solar collector which consist of a collector 15 co-axial heat pipes surrounded by a transparent envelope and which heat a fluid flowing through the condenser tubes have been predicted using heat transfer analytical methods. The analysis considers conductive and convective losses and energy transferred to a fluid flowing through the collector condenser tubes. The thermal performances of co-axial heat pipe solar collector is developed and are used to determine the collector efficiency, which is defined as the ratio of heat taken from the water flowing in the condenser tube and the solar radiation striking the collector absorber. The theoretical water outlet temperature and efficiency are compared with experimental results and it shows good agreement between them. The main advantage of this collector is that inclination of collector does not have influence on performance of co-axial heat pipe solar collector therefore it can be positioned at any angle from horizontal to vertical. In high building where the roof area is not enough the co-axial heat pipe solar collectors can be installed on the roof as well as wall of the building. The other advantage is each heat pipe can be topologically disconnected from the manifold.
Azad, E.
Roof detail, roof vent with star decoration, east section of ...
Roof detail, roof vent with star decoration, east section of roof - U.S. Department of the Treasury, South Court, Fifteenth Street & Pennsylvania Avenue Northwest, Washington, District of Columbia, DC
29. VIEW, LOOKING SOUTHEAST FROM STATION BUILDING ROOF, SHOWING ROOF OF WEST SHED - Pennsylvania Railroad, Harrisburg Station & Trainshed, Market & South Fourth Streets, Harrisburg, Dauphin County, PA
Thermal control surfaces experiment flight system performance
The Thermal Control Surfaces Experiment (TCSE) is the most complex system, other than the LDEF, retrieved after long term space exposure. The TCSE is a microcosm of complex electro-optical payloads being developed and flow by NASA and the DoD including SDI. The objective of TCSE was to determine the effects of the near-Earth orbital environment and the LDEF induced environment on spacecraft thermal control surfaces. The TCSE was a comprehensive experiment that combined in-space measurements with extensive post flight analyses of thermal control surfaces to determine the effects of exposure to the low earth orbit space environment. The TCSE was the first space experiment to measure the optical properties of thermal control surfaces the way they are routinely measured in a lab. The performance of the TCSE confirms that low cost, complex experiment packages can be developed that perform well in space.
Wilkes, Donald R.; Hummer, Leigh L.; Zwiener, James M.
Next Generation Roofs and Attics for Homes
Prototype residential roof and attic assemblies were constructed and field tested in a mixed-humid U.S. climate. Summer field data showed that at peak day irradiance the heat transfer penetrating the roof deck dropped almost 90% compared with heat transfer for a conventional roof and attic assembly. The prototype assemblies use a combination of strategies: infrared reflective cool roofs, radiant barriers, above-sheathing ventilation, low-emittance surfaces, insulation, and thermal mass to reduce the attic air temperature and thus the heat transfer into the home. The prototype assemblies exhibited attic air temperatures that did not exceed the peak day outdoor air temperature. Field results were benchmarked against an attic computer tool and simulations made for the densely populated, hot and dry southeastern and central-basin regions of California. New construction in the central basin could realize a 12% drop in ceiling and air-conditioning annual load compared with a code-compliant roof and attic having solar reflectance of 0.25 and thermal emittance of 0.75. In the hot, dry southeastern region of California, the combined ceiling and duct annual load drops by 23% of that computed for a code-compliant roof and attic assembly. Eliminating air leakage from ducts placed in unconditioned attics yielded savings comparable to the best simulated roof and attic systems. Retrofitting an infrared reflective clay tile roof with 1 -in (0.032-m) of EPS foam above the sheathing and improving existing ductwork by reducing air leakage and wrapping ducts with insulation can yield annual savings of about $200 compared with energy costs for pre-1980 construction.
Miller, William A [ORNL; Kosny, Jan [ORNL
Condensation Risk of Mechanically Attached Roof Systems in Cold Climate Zones
A white roof, cool roof, is constructed to decrease thermal loads from solar radiation, therefore saving energy by decreasing the cooling demands. Unfortunately, cool roofs with mechanically attached membrane, have shown to have a higher risk of intermediate condensation in the materials below the membrane in certain climates (Ennis & Kehrer, 2011) and in comparisons with similar construction with a darker exterior surface (Bludau, Zirkelbach, & Kuenzel, 2009). As a consequence, questions have been raised regarding the sustainability and reliability of using cool roof membranes in Northern U.S. climate zones. A white roof surface reflects more of the incident solar radiation in comparisons with a dark surface, which makes a distinguished difference on the surface temperature of the roof. However, flat roofs with either a light or dark surface and if facing a clear sky, are constantly losing energy to the sky due to the exchange of infrared radiation. This phenomenon exists both during the night and the day. During the day, if the sun shines on the roof surface, the exchange of infrared radiation typically becomes insignificant. During nights and in cold climates, the temperature difference between the roof surface and the sky can deviate up to 20 C (Hagentoft, 2001) which could result in a very cold surface temperature compared to the ambient temperature. Further, a colder surface temperature of the roof increases the energy loss and the risk of condensation in the building materials below the membrane. In conclusion, both light and dark coated roof membranes are cooled by the infrared radiation exchange during the night, though a darker membrane is more heated by the solar radiation during the day, thus decreasing the risk of condensation. The phenomenon of night time cooling from the sky and the lack of solar gains during the day is not likely the exclusive problem concerning the risk of condensation in cool roofs with mechanically attached membranes. Roof systems with thermoplastic membranes are prone to be more effected by interior air intrusion into the roof construction; both due to the wind induced pressure differences and due to the flexibility and elasticity of the membrane (Molleti, Baskaran, Kalinger, & Beaulieu, 2011). Depending on the air permeability of the material underneath the membrane, wind forces increase the risk of fluttering (also referred as billowing) of the thermoplastic membrane. Expectably, the wind induced pressure differences creates a convective air flow into the construction i.e. Page 2 air intrusion. If the conditions are right, moisture from the exchanging air may condensate on surfaces with a temperature below dew-point. The definite path of convective airflows through the building envelope is usually very difficult to determine and therefore simplified models (K nzel, Zirkelbach, & Scfafaczek, 2011) help to estimate an additional moisture loads as a result of the air intrusion. The wind uplifting pressure in combination with wind gusts are important factors for a fluttering roof. Unfortunately, the effect from a fluctuating wind is difficult to estimate as this is a highly dynamic phenomenon and existing standards (ASTM, 2011a) only take into account a steady state approach i.e. there is no guidance or regulations on how to estimate the air intrusion rate. Obviously, a more detailed knowledge on the hygrothermal performance of mechanically attached cool roof system is requested; in consideration to varying surface colors, roof air tightness, climate zones and indoor moisture supply.
Pallin, Simon B [ORNL
Why Cool Roofs?
By installing a cool roof at DOE, the federal government and Secretary Chu are helping to educate families and businesses about the important energy and cost savings that can come with this simple, low-cost technology. Cool roofs have the potential to quickly and dramatically reduce global carbon emissions while saving money every month on consumers' electrical bills.
Chu, Steven
Roofing Felt on Polystyrene.
A set of instructions is presented on methods to install compact flat roofs which, on the upper side of the supporting construction, are heat-insulated with expanded polystyrene and covered with roofing paper. Directions are also given for repairing, rero...
T. Isaksen E. M. Paulsen H. Juul
Environmentally Adaptable Roof Structure.
The patent application related to an energy-conserving roof structure for use in construction in low-slope roofs comprising two layers of permeable insulation and a layer of non-permeable insulation sandwiched between a pair of water vapor impermeable lay...
N. E. Nelson
Tension roofs and bridges
The term �Tension Structures� is commonly used for those structures wherein one or more primary load bearing elements are in tension. Such structures include membrane roofs, cable roofs, cable bridges, guyed masts or towers, cooling towers though some of these are less common. The tension elements are strands, ropes or membranes, which have to combine with structural elements carrying compression,
P Krishna
Thermal performance of double-skin facade with thermal mass
In order to mitigate the overheating problem in the warmer seasons, and thereby to improve thermal performance and energy efficiency of the Double-Skin Facade (DSF) system, this study introduced an innovative design approach involving the integration of thermal mass with the air channel of the conventional DSF. Then it proposed a numerical procedure to assess the thermal performance of DSF, and finally investigated the effect of thermal mass on the energy efficiency of such system. The initial step in the assessment procedure proposed the development of base-case models, which were able to predict temperature distribution in the DSF with a venetian blind. So too were the base-case models able to determine heating/cooling loads of the perimeter room for both the mechanically and naturally ventilated DSFs. In this procedure, building energy simulation software was used for base-case development; two distinct models were generated: an airflow model and a thermal model. The nodal, unidirectional airflow network method was applied in the case of the naturally ventilated DSF. The thermal model was a transient control volume method which found temperature distribution in discretized air-channel. The base-cases were verified at two levels: inter-model verification and verification relying on measurements from mechanically and naturally ventilated outdoor test-cells. At both levels, a generally fair agreement was obtained. After this, parametric studies pertaining to the energy performance of the system were conducted on the effect of thermal mass in unison with different air-channel configurations. Considerable energy load reductions were found when thermal mass was used in the air-channel, replacing venetian blind slats for mechanically ventilated DSFs; this held true during both summer and winter. In this configuration depending on the airflow path direction, energy savings from 21% to 26% in summer and from 41% to 59% in winter are achievable in compared with conventional DSF with aluminum venetian blind. The savings were found higher in sunny days than cloudy days. On the other hand, naturally ventilated DSFs combined with thermal mass were not found to be energy efficient in winter due to stack effect and airflow rate increase within the air channel.
Fallahi, Ali
The Thermal Control Surfaces Experiment (TCSE) is the most complex system retrieved after long term space exposure. The TCSE is a microcosm of complex electro-optical payloads being developed and flown. The objective of the TCSE on the LDEF was to determine the effects of the near-Earth orbital environment and the LDEF induced environment on spacecraft thermal control surfaces. The TCSE was a comprehensive experiment that combined in-space measurements with extensive post-flight analyses of thermal control surfaces to determine the effects of exposure to the low Earth orbit space environment. The TCSE was the first space experiment to measure the optical properties of thermal control surfaces the way they are routinely measured in the lab. The performance of the TCSE flight system on the LDEF was excellent.
Solar electric and thermal conversion system in close proximity to the consumer. [solar panels on house roofs
Solar cells may be used to convert sunlight directly into electrical energy and into lowgrade heat to be used for large-scale terrestrial solar-energy conversion. Both forms of energy can be utilized if such cells are deployed in close proximity to the consumer (rooftop). Cadmium-sulfide/copper-sulfide (CdS/Cu2S) solar cells are an example of cells which may be produced inexpensively enough to become economically attractive. Cell parameters relevant for combined solar conversion are presented. Critical issues, such as production yield, life expectancy, and stability of performance, are discussed. Systems-design parameters related to operating temperatures are analyzed. First results obtained on Solar One, the experimental house of the University of Delaware, are given. Economic aspects are discussed. Different modes of operation are discussed in respect to the power utility and consumer incentives.
Boeer, K. W.
Performance potential of advanced solar thermal propulsion
Design features, component test results, and performance levels of a solar thermal propulsion system for transferring payloads from LEO to GEO are detailed. Solar radiation is collected by two inflated paraboloidal reflectors which funnel the light into a radiant cavity through which propellant is flowing. The propellant, preferably H2 due to its high specific impulse at low temperatures, is then
Thermal performance of managed window systems
The primary factors that determine the net thermal performance of a window system are its overall heat transfer rate (U-value), its air leakage characteristics and its sun control capability. With managed window systems these basic properties may be drastically altered on an hourly basis as movable insulating and shading devices are deployed over the prime windows. A large building energy
S. E. Selkowitz; V. Bazjanac
Roof bolting equipment & technology
Technology provides an evaluator path to improvement for roof bolting machines. Bucyrus offers three different roof bolts models for various mining conditions. The LRB-15 AR is a single-arm boiler recommended for ranges of 32 inches and above; the dual-arm RB2-52A for ranges of 42 inches and above; and the dual-arm RB2-88A for ranges of 54 inches and above. Design features are discussed in the article. Developments in roof bolting technology by Joy Mining Machinery are reported. 4 photos.
Fiscor, S.
EPA Science Inventory
One of the most interesting stormwater control systems under evaluation by EPA are ?green roofs?. Green roofs are vegetative covers applied to building roofs to slow, or totally absorb, rainfall runoff during storms. While the concept of over-planted roofs is very ancient, the go...
Mine roof support plate
A support plate is disclosed for a mine roof including a substantially flat body engageable with the mine roof, the body having an enlarged central opening through which are passed one end of a roof bolt on which is threaded an expansion shell which is inserted into a mine roof opening. Ribs extend longitudinally of the flat body on both sides of the central opening for additional strength. The ribs are spaced a predetermined distance apart on opposite sides of the central opening. Centering members are provided on the body portion intermediate the ribs on opposite sides of the central opening, the centering members and ribs serving to center the washer and bolt portion of the bolt assembly.
White, C.C.
Science Nation: Green Roofs
The rooftops of Manhattan are as varied as the city itself. But on some, something new is taking root--literally! A green roof is a continuous layer of living plants. Looking down several stories from the windows of neighboring buildings, the rooftop resembles a well-manicured, suburban lawn that is simply contained within the boundaries of a flat Manhattan rooftop. Researchers are investigating what benefits green roofs might have on harsh urban environments.
Thermal interface pastes nanostructured for high performance
Thermal interface materials in the form of pastes are needed to improve thermal contacts, such as that between a microprocessor and a heat sink of a computer. High-performance and low-cost thermal pastes have been developed in this dissertation by using polyol esters as the vehicle and various nanoscale solid components. The proportion of a solid component needs to be optimized, as an excessive amount degrades the performance, due to the increase in the bond line thickness. The optimum solid volume fraction tends to be lower when the mating surfaces are smoother, and higher when the thermal conductivity is higher. Both a low bond line thickness and a high thermal conductivity help the performance. When the surfaces are smooth, a low bond line thickness can be even more important than a high thermal conductivity, as shown by the outstanding performance of the nanoclay paste of low thermal conductivity in the smooth case (0.009 mum), with the bond line thickness less than 1 mum, as enabled by low storage modulus G', low loss modulus G" and high tan delta. However, for rough surfaces, the thermal conductivity is important. The rheology affects the bond line thickness, but it does not correlate well with the performance. This study found that the structure of carbon black is an important parameter that governs the effectiveness of a carbon black for use in a thermal paste. By using a carbon black with a lower structure (i.e., a lower DBP value), a thermal paste that is more effective than the previously reported carbon black paste was obtained. Graphite nanoplatelet (GNP) was found to be comparable in effectiveness to carbon black (CB) pastes for rough surfaces, but it is less effective for smooth surfaces. At the same filler volume fraction, GNP gives higher thermal conductivity than carbon black paste. At the same pressure, GNP gives higher bond line thickness than CB (Tokai or Cabot). The effectiveness of GNP is limited, due to the high bond line thickness. A thermal paste that is particularly effective for smooth surfaces was obtained by using nanoclay platelets (obtained by organic modification and subsequent chemical exfoliation) as the solid component. The superiority of the nanoclay paste for smooth surfaces is attributed to the submicrometer bond line thickness. Electrically nonconductive high-performance thermal paste was obtained by using either fumed alumina or fumed zinc oxide. The nonconductivity serves to avoid short circuiting in the electronic application environment. The fumed oxides are as effective as carbon black, but are advantageous in their electrical nonconductivity. Without fuming, the oxides are less effective. The silane coating on fumed metal oxides helps. Electrically nonconductive thermal pastes have also been attained using carbon as the thermally conductive solid component. Either fumed alumina or nanoclay is used to break the electrical connectivity of the carbon in the paste to obtain electrical nonconductivity. Among the nanostrucutred pastes developed in this dissertation research, the nanoclay (0.6 vol.%) paste is recommended for smooth surfaces. With the overall performance for smooth and rough surfaces considered, the carbon black (Tokai, 15 vol.%) paste is recommended. Carbon black (Tokai) is more effective than carbon black (Cabot), due to its small aggregate size. All the pastes developed are much more effective than carbon nanotube arrays investigated by others. The rheological behavior of the thermal pastes was studied under strain sweep, frequency sweep, steady state flow and temperature ramping. In the absence of a solid component, the vehicle is Newtonian and fluid-like. In the presence of a solid component, the paste is a Bingham plastic that exhibits shear thinning and mainly solid-like behavior. The addition of antioxidants enhances the solid-like character, increases the yield stress, the plastic viscosity and the bond line thickness, and decreases the thermal contact conductance. Double yielding behavior was observed in the CB(Cabot) and CB(Tokai) pastes, but not in t
Lin, Chuangang
The effect of air infiltration on the thermal performance of a small metal-framed assembly
Innovative construction materials and systems have generated a need for laboratory scale tests to quantify the effect of air leakage on thermal and moisture performance of building assemblies. Some construction materials and systems are inherently more air tight than others. It is desirable to do laboratory scale measurements on alternative systems so as to rank them with respect to air tightness just as they can be ranked with respect to system R-value. Participants in summer 1995 and 1996 workshops for elementary and secondary school science teachers in the Buildings Technology Center (BTC) at the Oak Ridge National Laboratory sought a way to illustrate basic principles of building science in the classroom. They decided to build a small metal-framed assembly with internal volume of 44 ft{sup 3} (1.25 m{sup 3}) and removable wall sheathing. The assembly included a door and window. Although the door and window were made from 4-in. (10.2-cm) thick foam insulation, the requisite framing for them detracted from the thermal performance of the walls and occupied a disproportionately large fraction of the wall area. The floor and roof of the assembly were also well-insulated so that the walls dominated the conduction heat loss through the assembly. The plan was to test thermal performance of the assembly with the sheathing and without it. Thereby the teachers hoped to show the effects of thermal bridges with metal framing as well as practical yet insightful way to reduce their effects.
Petrie, T.W.; Christian, J.E.; Childs, P.W. [Oak Ridge National Lab., TN (United States). Energy Div.
Thermal Performance of Lightweight Solar Housing for Peri-urban Villages
This study concerns an investigation into the thermal performance of prefabricated lightweight houses for peri-urban villages in the Perth Metropolitan region of Western Australia. Several styles of residence were selected for comparison taken from three constructed ``lifestyle villages''. National Lifestyle Villages Pty Ltd (NLV) is committed to quadruple bottom-line sustainability and the aim was, therefore, to provide indicators of how old and new dwellings compared under the same external conditions. The buildings themselves are prefabricated and brought to site in two halves, framed in steel clad with fibre-cement boarding, roofed in zincalume sheeting, and timber floored with applied fibre-cement sheeting. Although designed using passive solar design principles and other energy conservation measures they possess little thermal mass to improve the thermal performance. Research by the author indicated several feasible and low-budget innovative improvements for future designs, and how best to retrofit existing dwellings. NLV's aim is to provide homes for over 40,000 people in 100 villages Australia-wide by the year 2025. Any improvement in residential thermal performance can be translated not only into energy savings and greenhouse gas reduction on a significant scale, but can enhance comfort levels for residents whilst reducing their energy costs.
Goodfield, D.; Anda, M.; Hammond, R.; Mathew, K.
Thermal performance of radiative cooling panels
The performance of panels which cool by means of thermal infrared heat transfer to the sky is calculated from basic principles. The efficiency of a radiative cooling panel is defined. Computer calculations with the full heat transfer equations are performed for horizontal surfaces with infrared-transparent covers. Plots of efficiency versus a dimensionless temperature difference are shown to be insensitive to variations in air temperature, wind speed, and sky radiance, resulting in plots analogous to standard efficiency curves for solar panels. Experimental measurements show that, for most applications, white paint is a better radiator than aluminized polyvinyl fluoride film.
Berdahl, P.; Martin, M.; Sakkal, F.
Thermal Degradation of Fire-Retardant-Treated Plywood: Development and Evaluation of a Test Protocol.
Although untreated plywood has given satisfactory performance as roof sheathing for more than 50 years, some fire-retardant-treated plywood products have not performed satisfactorily in recent years. Thermally induced in-service failures have occurred wit...
C. R. McIntyre J. E. Winandy R. J. Ross S. L. LeVan S. P. Hoffman
Thermal performance of aircraft polyurethane seat cushions
Measurements were conducted on 7.6 x 7.6 cm samples of polyurethane seat cushion material in a modified National Bureau of Standards smoke density chamber to simulate real life conditions for an onboard aircraft fire or post-crash fire. In this study, a non-flaming heat radiation condition was simulated. Two aluminized polymeric fabrics (Norfab 11HT-26-A and Preox 1100-4) and one neoprene type material in two thicknesses (Vonar 2 and 3) were tested as heat blocking layers to protect the urethane foam from rapid heat degradation. Thermogravimetric analysis and differential scanning calorimetry were performed to characterize thermally the materials tested. It was found that Vonar 2 or 3 provided approximately equal thermal protection to F.R. urethane as the aluminized fabrics, but at a significant weight penalty. The efficiency of the foams to absorb heat per unit mass loss when protected with the heat blocking layer decreases in the heating range of 2.5-5.0 W/sq cm, but remains unchanged or slightly increases in the range of 5.0-7.5 W/sq cm. The results show that at all heat flux ranges tested the usage of a heat blocking layer in aircraft seats significantly improves their thermal performance.
Kourtides, D. A.; Parker, J. A.
Thermal Performance of Aircraft Polyurethane Seat Cushions
Aircraft seat materials were evaluated in terms of their thermal performance. The materials were evaluated using (a) thermogravimetric analysis, (b) differential scanning calorimetry, (c) a modified NBS smoke chamber to determine the rate of mass loss and (d) the NASA T-3 apparatus to determine the thermal efficiency. In this paper, the modified NBS smoke chamber will be described in detail since it provided the most conclusive results. The NBS smoke chamber was modified to measure the weight loss of material when exposed to a radiant heat source over the range of 2.5 to 7.5 W/sq cm. This chamber has been utilized to evaluate the thermal performance of various heat blocking layers utilized to protect the polyurethane cushioning foam used in aircraft seats. Various kinds of heat blocking layers were evaluated by monitoring the weight loss of miniature seat cushions when exposed to the radiant heat. The effectiveness of aluminized heat blocking systems was demonstrated when compared to conventional heat blocking layers such as neoprene. All heat blocking systems showed good fire protection capabilities when compared to the state-of-the-art, i.e., wool-nylon over polyurethane foam.
Heat transfer characteristics and optimum insulation thickness for Hordi roofs using a pseudo one-dimensional dynamic model
Rib-slab (Hordi) roofs are commonly used in the construction of buildings in Saudi Arabia. Compared to the traditional solid-slab roofs, Hordi roofs are lighter and have higher thermal and acoustic resistances. Despite their widespread use in recent years, only little information is available regarding their thermal characteristics in general, and none under optimised insulation conditions. The geometrical configuration of the
S. A. Al-Sanea; M. F. Zedan
Development of Mitsubishi High Thermal Performance Grid
Mitsubishi has developed a new zircalloy grid spacer for PWR fuel with higher thermal performance. Computational Fluid Dynamics (CFD) evaluation method has been applied for designing of the new lower pressure loss and higher Departure from Nucleate Boiling (DNB) benefit grid spacer. Reduction of pressure loss of grid structures has been examined by CFD. Also, CFD has been developed as a design tool to predict the coolant mixing ability of vane structures, which is to compare the relative peak spot temperatures around fuel rods at the same heat flux condition. Prototype grids were manufactured and several tests, which were pressure loss measurements, cross-flow measurements and freon DNB tests, were conducted to verify CFD predictions. It is concluded that the applicability of the CFD evaluation method for the thermal hydraulic design of the grid is confirmed.
Ikeda, Kazuo; Hoshi, Masaya
Up on the Roof: A Systematic Approach to Roof Maintenance.
A systematic roof maintenance program is characterized by carefully prepared long- and short-range plans. An essential feature of a systematic approach to roof maintenance is the stress on preventive measures rather than the patching of leaks. (Author)
Burd, William
8. Detail of interior roof showing truss bracing and roof ...
8. Detail of interior roof showing truss bracing and roof plank decking; view to east from approximately the center of the shelter. - Warm River Shelter, Warm River Campground, Ashton, Fremont County, ID
24. Roof detail from liftbed truck, showing pan roof above ...
24. Roof detail from lift-bed truck, showing pan roof above breezeway, with sawn redwood trim, tube-type drains; note missing rain gutter at roof edge, deteriorated condition of slates; view to south, 90mm lens. - Southern Pacific Depot, 559 El Camino Real, San Carlos, San Mateo County, CA
The Nuclear Nonproliferation Programs Design Authority is in the design stage of the Waste Solidification Building (WSB) for the treatment and solidification of the radioactive liquid waste streams generated by the Pit Disassembly and Conversion Facility (PDCF) and Mixed Oxide (MOX) Fuel Fabrication Facility (MFFF). The waste streams will be mixed with a cementitious dry mix in a 55-gallon waste container. Savannah River National Laboratory (SRNL) has been performing the testing and evaluations to support technical decisions for the WSB. Engineering Modeling & Simulation Group was requested to evaluate the thermal performance of the 55-gallon drum containing hydration heat source associated with the current baseline cement waste form. A transient axi-symmetric heat transfer model for the drum partially filled with waste form cement has been developed and heat transfer calculations performed for the baseline design configurations. For this case, 65 percent of the drum volume was assumed to be filled with the waste form, which has transient hydration heat source, as one of the baseline conditions. A series of modeling calculations has been performed using a computational heat transfer approach. The baseline modeling results show that the time to reach the maximum temperature of the 65 percent filled drum is about 32 hours when a 43 C initial cement temperature is assumed to be cooled by natural convection with 27 C external air. In addition, the results computed by the present model were compared with analytical solutions. The modeling results will be benchmarked against the prototypic test results. The verified model will be used for the evaluation of the thermal performance for the WSB drum.
Lee, S
49 CFR 195.405 - Protection against ignitions and safe access/egress involving floating roofs.
Code of Federal Regulations, 2010 CFR
...egress involving floating roofs. (a) After...aboveground breakout tanks must be in accordance...particular breakout tank. (b) The hazards...access/egress onto floating roofs of in-service aboveground breakout tanks to perform...
Thermal Performance of the XRS Helium Insert
The X-Ray Spectrometer (XRS) is an instrument on the Japanese Astro-E satellite, scheduled for launch early in the year 2000. The XRS Helium Insert comprises a superfluid helium cryostat, an Adiabatic Demagnetization Refrigerator (ADR), and the XRS calorimeters with their cold electronics. The calorimeters are capable of detecting X-rays over the energy range 0.1 to 10 keV with a resolution of 12 eV. The Helium Insert completed its performance and verification testing at Goddard in January 1999. It was shipped to Japan, where it has been integrated with the neon dewar built by Sumitomo Heavy Industries. The Helium Insert was given a challenging lifetime requirement of 2.0 years with a goal of 2.5 years. Based on the results of the thermal performance tests, the predicted on-orbit lifetime is 2.6 years with a margin of 30%. This is the result of both higher efficiency in the ADR cycle and the low temperature top-off, more than compensating for an increase in the parasitic heat load. This paper presents a summary of the key design features and the results of the thermal testing of the XRS Helium Insert.
Breon, Susan R.; DiPirro, Michael J.; Tuttle, James G.; Shirron, Peter J.; Warner, Brent A.; Boyle, Robert F.; Canavan, Edgar R.
ACCESS: Thermal Mechanical Design, Performance, and Status
Systematic errors associated with astrophysical data used to probe fundamental astrophysical questions, such as SNeIa observations used to constrain dark energy theories, are now rivaling and exceeding the statistical errors associated with these measurements. ACCESS: Absolute Color Calibration Experiment for Standard Stars is a series of rocket-borne sub-orbital missions and ground-based experiments designed to enable improvements in the precision of the astrophysical flux scale through the transfer of absolute laboratory detector standards from the National Institute of Standards and Technology (NIST) to a network of stellar standards with a calibration accuracy of 1% and a spectral resolving power of 500 across the 0.35 - 1.7?m bandpass. Achieving this level of accuracy requires characterization and stability of the instrument and detector including a thermal background that contributes less than 1% to the flux per resolution element in the NIR. We will present the instrument and calibration status with a focus on the thermal mechanical design and associated performance data. The detector control and performance will be presented in a companion poster (Morris, et al). NASA APRA sounding rocket grant NNX08AI65G supports this work.
Kaiser, Mary Elizabeth; Morris, M. J.; McCandliss, S. R.; Rauscher, B. J.; Kimble, R. A.; Kruk, J. W.; Wright, E. L.; Bohlin, R.; Kurucz, R. L.; Riess, A. G.; Pelton, R.; Deustua, S. E.; Dixon, W. V.; Sahnow, D. J.; Benford, D. J.; Gardner, J. P.; Feldman, P. D.; Moos, H. W.; Lampton, M.; Perlmutter, S.; Woodgate, B. E.
Code check floating tank roofs
This paper reports that both API 650 and BS 2654 contain criteria for design of single deck pontoon-type tank floating roofs. The codes states that the floating roof shall have sufficient buoyancy to remain afloat under the following conditions: tank content specific gravity is 0.7; the roof center deck is punctured; any two adjacent pontoon compartments are punctured; no water or live loads are present; and the roof primary drain is inoperative.
Hassan, H.M.K. (Abu Dhabi Marine Operating Co. (United Arab Emirates))
High-Tech Roof Management.
Describes the use of a computerized roof management system (CRMS) for school districts to foster multiple roof maintenance efficiency and cost effectiveness. Highlights CRMS software manufacturer choices, as well as the types of nondestructive testing equipment tools that can be used to evaluate roof conditions. (GR)
Benzie, Tim
This paper reports that both API 650 and BS 2654 contain criteria for design of single deck pontoon-type tank floating roofs. The codes states that the floating roof shall have sufficient buoyancy to remain afloat under the following conditions: tank content specific gravity is 0.7; the roof center deck is punctured; any two adjacent pontoon compartments are punctured; no water
Green roofs: potential at LANL
Green roofs, roof systems that support vegetation, are rapidly becoming one of the most popular sustainable methods to combat urban environmental problems in North America. An extensive list of literature has been published in the past three decades recording the ecological benefits of green roofs; and now those benefits have been measured in enumerated data as a means to analyze
Pacheco; Elena M
Hail Resistance of Roofing Products.
A test was developed for evaluating the hail resistance of roofings, in which synthetic hail-stones (ice spheres) of various sizes were shot at roof assemblies at their free-fall terminal velocities. Indentations, granule loss and roofing fracture were ob...
S. H. Greenfeld
Thermal performance of plate-fin vapor chamber heat sinks
Since vapor chambers exhibit excellent thermal performance, they are suited to use as bases of heat sinks. This work experimentally studies the thermal performance of plate-fin vapor chamber heat sinks using infrared thermography. The effects of the width, height and number of fins and of the Reynolds number on the thermal performance are considered. Experimental data are compared with corresponding
Hung-Yi Li; Ming-Hung Chiang; Chih-I Lee; Wen-Jei Yang
30 CFR 75.204 - Roof bolting.
...2009-07-01 false Roof bolting. 75.204 Section...Support § 75.204 Roof bolting. (a) For roof bolts...Specification for Roof and Rock Bolts and Accessories...deterioration. (d) When washers are used with roof bolts... (4) In each roof bolting cycle, the...
Maintenance and Repair of Sprayed Polyurethane Foam Roofing.
This report is intended to assist Bureau of Reclamation field personnel in the maintenance of SPF (sprayed polyurethane foam) roofing systems. No roof system can be expected to provide good long-term performance without some attention to maintenance and r...
J. J. Swihart R. L. Alumbaugh
Performance Evaluation of Automatic Extraction System. Volume V. Geotechnical Investigations of the Roof Conditions in the Area Mined by the AES Machine. Final Technical Report.
This report presents the results of an in-depth geotechnical investigation aimed at assessing the roof, floor, and coal pillar conditions in the area mined by an experimental Automatic Extraction System (AES), built by National Mine Service Co. The study ...
D. A. Newman F. Rafia Z. T. Bieniawski
Comparison between aesthetic and thermal performances of copper oxide and titanium dioxide nano-particulate coatings
Nano-particulate coatings with high reflectance against solar irradiation can control undesirable thermal heating by sunlight absorption. It can reduce the energy consumption for air conditioning of houses and cars. For the objects covered by these coatings and subjected to human sight, e.g. roofing surfaces, high dazzle of reflected visible light can offend the human eyes and spoil the fine view
Mehdi Baneshi; Shigenao Maruyama; Atsuki Komiya
3.2: New Directions in Green Roof Research GREEN ROOF RESEARCH IN BRITISH COLUMBIA AN OVERVIEW
In 2002 a stakeholder workshop held in Vancouver identified the major barriers to the market penetration of green roofs in BC as the lack of climate-specific performance data, the absence of third party testing and verification of green roof systems, and a lack of demonstrated feasibility. To address these issues the British Columbia Institute of Technology (BCIT), supported by a
Maureen Connelly; Karen Liu
Numerical Simulations of a Roof-Top Wind Turbine
Unsteady numerical simulations of a high efficiency roof-top wind turbine have been performed. The wind turbine cross section design was based on geometrical optimization study of Rahai and Hefazi for increasing contributions of the lift force to the torque, resulting in significant improvements in the performance of a vertical axis wind turbine. The wind turbine was 30 cm in diameter and 75 cm length, with 45 cm diameter end-plates, placed in the spanwise direction above a 26 degree slanted roof at 20 percent from the roof's highest elevation and one turbine diameter away from the roof surface. The approaching wind velocity was 30 m/sec and the wind turbine RPM was 233. Results indicate nearly 20 percent improvements in the power output, when compared with the corresponding results for a free standing wind turbine. However, the wind turbine operation imposes oscillatory stress on the roof, which could results in structural vibration and damage and noise generation.
Moayedian, Shahab; Rahai, Hamid
Thermal performance limits of polymer composite pin fin heat sinks
The thermal performance limits of air cooled heat sinks made of a polyphenylene sulphide composite (PPS, 20W\\/m-K), are predicted and compared to aluminum and copper pin fin heat sinks, using a defined heat sink volume and a range of pumping powers. The thermal performance is analytically predicted across an extensive parametric space in terms of the primary thermal metrics and
Raj Bahadur; Avram Bar-Cohen
Performance of thermal adhesives in forced convection
Cooling is critical for the life and performance of electronic equipment. In most cases cooling may be achieved by natural convection but forced convection may be necessary for high wattage applications. Use of conventional type heat sinks may not be feasible from the viewpoint of specific applications and the costs involved. In a heat sink, fins can be attached to the well by ultrasonic welding, by soldering, or with a number of industrially available thermal adhesives. In this paper, the author investigates the heat transfer characteristics of several adhesives and compares them with ultrasonic welding and theoretically calculated values. This experiment was conducted in an air flow chamber. Heat was generated by using heaters mounted on the well. Thermstrate foil, Uniset A401, and Aremco 571 adhesives were tested along with an ultrasonically welded sample. Ultrasonic welding performed far better than the adhesives and Thermstrate foil. This type of experiment can be adapted for a laboratory exercise in an upper level heat transfer course. It gives students an exposure to industrial applications that help them appreciate the importance of the course material.
Kundu, Nikhil K.
WMAP Observatory Thermal Design and On-Orbit Thermal Performance
The Wilkinson Microwave Anisotropy Probe (WMAP) observatory, launched June 30, 2001, is designed to measure the cosmic microwave background radiation with unprecedented precision and accuracy while orbiting the second Lagrange point (L2). The instrument cold stage must be cooled passively to <95K, and systematic thermal variations in selected instrument components controlled to less than 0.5 mK (rms) per spin period. This paper describes the thermal design and testing of the WMAP spacecraft and instrument. Flight thermal data for key spacecraft and instrument components are presented from launch through the first year of mission operations. Effects of solar flux variation due to the Earth's elliptical orbit about the sun, surface thermo-optical property degradations, and solar flares on instrument thermal stability are discussed.
Glazer, Stuart D.; Brown, Kimberly D.; Michalek, Theodore J.; Ancarrow, Walter C.
Thermal performance measurement for confined heat sinks
The convective heat transfer characteristics for confined heat sinks by using two experimental methods such as the improved transient liquid crystal method and thermal testing method have been systematically investigated. The trends of average effective heat transfer coefficients measured by using transient liquid crystal method are consistent with that by using thermal testing method. The deviation of the results evaluated
T. S. Chai; J. T. Horng; T. Y. Wu; Y. H. Hung
Thermal performance of insulating window systems
Energy efficient windows coupled with window management strategies can alter the role of windows from that of an energy drain to a net supplier of energy to the building. This will require effective utilization of winter solar gain and daylight, coupled with reductions in thermal losses. Thermal losses of conventional double glazing are less than those of single glass but
A Meta-Analysis of Performance Response Under Thermal Stressors
Objective: Quantify the effect of thermal stressors on human performance. Background: Most reviews of the effect of environmental stressors on human performance are qualitative. A quantitative review provides a stronger aid in advancing theory and practice. Method: Meta-analytic methods were applied to the available literature on thermal stressors and performance. A total of 291 references were collected. Forty-nine publications met
Peter A. Hancock; Jennifer M. Ross; James L. Szalma
Integrated assessment of thermal performance and room acoustics
The acoustical and thermal properties of materials have contradictory behaviour. Constructions, which provide good acoustic absorption usually, have a low thermal inertia and vice versa. It is therefore important to find a balance between acoustic absorption and thermal inertia in order to deliver well designed buildings. This paper presents an integrated solution, developed to assess the room acoustics performance of
Citherlet St�phane; Macdonald Iain
40 CFR 65.43 - Fixed roof with an internal floating roof (IFR).
... false Fixed roof with an internal floating roof (IFR). 65.43 Section 65...65.43 Fixed roof with an internal floating roof (IFR). (a) IFR design requirements...by using a fixed roof and an internal floating roof shall comply with the design...
Code of Federal Regulations, 2013 CFR
Performance of a solar-thermal collector
Possible means of achieving the technology required for field application of solar thermal power systems are discussed. Simplifications in construction techniques as well as in measurement techniques for parabolic trough collectors are described. Actual measurement data is also given.
Higa, W. H.
Q-Flex Accelerometer Thermal Performance Study.
The significance of this investigative effort to the Air Force is in the pursuit of low cost accelerometer with low thermal sensitivity and suitable for strapped down system application. The results of this Air Force research and development program indic...
N. J. Klein D. B. Grindeland B. D. Strachan
12. CENTRAL ROOF TRUSS AND ROOF SUPPORT BEAMS OF SARATOGA GAS LIGHT COMPANY GASHOLDER NO. 2 HOUSE, LOOKING WEST. THE WIRES AND BEAM AT RIGHT OF PHOTOGRAPH HAVE BEEN ADDED TO STABILIZE TRUSS SYSTEM. - Saratoga Gas Light Company, Gasholder No. 2, Niagara Mohawk Power Corporation Substation Facility, intersection of Excelsior & East Avenues, Saratoga Springs, Saratoga County, NY
13. ONE OF TWO LATERAL ROOF TRUSSES AND ROOF SUPPORT BEAMS OF SARATOGA GAS LIGHT COMPANY GASHOLDER NO. 2 HOUSE LOOKING WEST. THE WIRES AND BEAM AT RIGHT CENTER OF PHOTOGRAPH HAVE BEEN ADDED TO STABILIZE TRUSS SYSTEM - Saratoga Gas Light Company, Gasholder No. 2, Niagara Mohawk Power Corporation Substation Facility, intersection of Excelsior & East Avenues, Saratoga Springs, Saratoga County, NY
An Experimental Study of Casing Performance Under Thermal Cycling Conditions
The authors have investigated the behavior of casing pipe body and connections under simulated thermal recovery conditions. The study, performed in a new computer-controlled thermal-well simulator, examined the thermal stress behavior and leak resistance of pipe and connections at temperatures up to 354°C (670°F) under severe loading conditions similar to those encountered in thermal wells. We also studied the biaxial
Kazushi Maruyama; Eiji Tsuru; Masao Ogasawara; Yasusuke Inoue; Ekwere Peters
Design Methodology for Standing Secondary Roof Support in Longwall Tailgates.
This paper discusses a design methodology for standing secondary tailgate supports. The methodology uses the performance characteristics generated in the NIOSH Mine Roof Simulator (MRS) to match the stiffness and load characteristics of various supports t...
D. R. Dolinar T. M. Barczak T. P. Mucho
In June 2001, the City of Chicago revised its energy code. As a result, all low-slope roof systems constructed were prescribed to have a minimum thermal resistance along with an initial solar reflectivity of 0.65. After three years, the roof reflectivity was to achieve a minimum of 0.50 (washed or unwashed). A Roofing Industry Alliance was formed and a study
Interconnect technologies and the thermal performance of MCM
The thermal performances of multichip modules (MCMs) are compared on the basis of their interconnection technologies. The comparisons are made for hermetic and conduction cooled use environments. The thermal performances of the chip-first-type high density interconnect (HDI) technology, the flipped chip (FCP) technology, and the flipped tape automated bond (FTAB) technology are analyzed and compared for the MCM applications. The
Burhan Ozmat
Floating roof storage tank boilover
Storage tanks are important facilities for the major hazard installations (MHIs) to store large quantity of crude oil. There is several fire types can occur with large diameter open top floating roof storage tanks. Boilover is considered one of the most dangerous fires in large-scale oil tank. The world has witnessed many incidents due to boilover in floating roof storage
Ibrahim M. Shaluf; Salim A. Abdullah
Investigation of the Mechanical Performance of Compliant Thermal Barriers
Compliant thermal barriers play a pivotal role in the thermal protection systems of advanced aerospace vehicles. Both the thermal properties and mechanical performance of these barriers are critical in determining their successful implementation. Due to the custom nature of many thermal barriers, designers of advanced spacecraft have little guidance as to the design, selection, and implementation of these elements. As part of an effort to develop a more fundamental understanding of the interrelationship between thermal barrier design and performance, mechanical testing of thermal barriers was conducted. Two different types of thermal barriers with several core insulation density levels ranging from 62 to 141 kg/cu m were investigated. Room-temperature compression tests were conducted on samples to determine load performance and assess thermal barrier resiliency. Results showed that the loading behavior of these thermal barriers was similar to other porous, low-density, compliant materials, such as elastomeric foams. Additionally, the insulation density level had a significant non-linear impact on the stiffness and peak loads of the thermal barriers. In contrast, neither the thermal barrier type nor the level of insulation density significantly influenced the room-temperature resiliency of the samples.
DeMange, Jeffrey J.; Bott, Robert J.; Dunlap, Patrick H.
The Successful Transfer of Space Derived Convergent Spray: An Application for Industrial Roof Coatings and Interstate Bridge Repair
A partnership was formed between the National Aeronautics and Space Administration (NASA), the Environmental Protection Agency (EPA), and United Technologies USBI Company to develop, demonstrate, and evaluate a technology that uses a solventless spray process for depositing a lightweight, highly filled roof coating on low-sloped commercial roofs. Although the levels of volatile organic compound (VOC) emissions from industrial roof coating's and paint operations have been reduced in recent years, this partnership,was an effort to further reduce VOC emission levels and to also demonstrate the use of reclaimed automobile tire rubber as a filler material in roof coating systems. Different materials and coatings were evaluated and tested before the final selection used to coat the roofs of two small buildings at NASA's Marshall Space Flight Center during fiscal year 1997. The project successfully leveraged the investment of EPA, NASA and private sector resources to demonstrate a pre-commercial roofing coating process. This process utilizes the Convergent Spray Technologies process, which was initially developed by USBI to apply highly-filled, thermal protection coatings to the Space Shuttle Solid Rocket Boosters. A second partnership between the NASA, Federal Highway Administration, Alabama Department of Transportation and USBI Company was formed to develop and demonstrate the Convergent Spray Technology as a method of applying a skid resistant coating to interstate roads and concrete bridge decking's. Again, different materials and coatings were evaluated and tested before the final selection of ground flint and resin. Two field demonstrations were performed during fiscal year 1997 for the purpose of evaluating the coating system under actual highway conditions. These coatings were applied on Interstate 65 near Huntsville Alabama, and in the Mobile Bankhead tunnel. The system performed this task without the use of harmful solvents, and accomplished the process in a single application. This project successfully leveraged the investment of NASA, Federal Highway Administration, the Alabama Department of Transportation, and private sector funding.
McMillan, Vernotto C.
Field study on the thermal environment of passive cooling system in RC building
In recent years, various passive methods have come to be adopted in architecture design. The rooftop lawn is seen to have merit in the reduction in the air conditioning load of the building, as well as contributing to the mitigation of the heat island phenomenon. The roofs praying system is seen to be an effective method for the roof of low heat insulation performance, and can greatly reduce the heat load in the summer season. However, at present most of the buildings with an RC construction have the insulating material in the roof for providing thermal insulation in the winter season. There has been a trend to adopt the roof spraying system actively in even such a general RC building, but it is not clear how much actual effect it has. In this study, the authors conducted a measurement in an RC building with a rooftop spraying system and roof lawn in order to clarify the effects and problems on the thermal environment.
Zhou, Nan; Gao, Weijun; Nishida, Masaru; Kitayama, Hiroki; Ojima, Toshio
Finding Parameters by Tabu Search Algorithm to Construct a Coupled Heat and Mass Transfer Model for Green Roof
Green roof has the advantage to lower building temperature; therefore it has been applied a lot nowadays to indoor temperature adjustment. This study builds a coupled heat and mass transfer model, in which the water vapor in the substrate is taken into consideration, based on the concept of energy balance. With the parameters optimized by Tabu search algorithm, data from the experiment is used to validate the model. In the study, both the model and the experimental green roof of this study consist of four layers: canopy, substrate, drainage and concrete rooftop. Heat flux of each layer is calculated in the model, using energy balance equations as well as some numerical methods to simulate water-related thermal effect in soil, to see the heat transfer process. The experiment site locates on the rooftop of Hydrotech Research Institute, National Taiwan University, Taiwan. Since the material of the substrate layer has high porosity, the results show a contradiction of energy conservation when neglecting the influence of water. It is found that the parameters identified by Tabu search seem reasonable for the experiment. The main contribution of the study is to construct a thermal model for green roof with parameter optimization procedure, which can be used as an effective assessment method to quantify the heat-reduced performance of green roof on the underlying building.
Chen, P.; Tung, C.
Effects of Solar Photovoltaic Panels on Roof Heat Transfer
Building Heating, Ventilation and Air Conditioning (HVAC) is a major contributor to urban energy use. In single story buildings with large surface area such as warehouses most of the heat enters through the roof. A rooftop modification that has not been examined experimentally is solar photovoltaic (PV) arrays. In California alone, several GW in residential and commercial rooftop PV are approved or in the planning stages. With the PV solar conversion efficiency ranging from 5-20% and a typical installed PV solar reflectance of 16-27%, 53-79% of the solar energy heats the panel. Most of this heat is then either transferred to the atmosphere or the building underneath. Consequently solar PV has indirect effects on roof heat transfer. The effect of rooftop PV systems on the building roof and indoor energy balance as well as their economic impacts on building HVAC costs have not been investigated. Roof calculator models currently do not account for rooftop modifications such as PV arrays. In this study, we report extensive measurements of a building containing a flush mount and a tilted solar PV array as well as exposed reference roof. Exterior air and surface temperature, wind speed, and solar radiation were measured and thermal infrared (TIR) images of the interior ceiling were taken. We found that in daytime the ceiling surface temperature under the PV arrays was significantly cooler than under the exposed roof. The maximum difference of 2.5 C was observed at around 1800h, close to typical time of peak energy demand. Conversely at night, the ceiling temperature under the PV arrays was warmer, especially for the array mounted flat onto the roof. A one dimensional conductive heat flux model was used to calculate the temperature profile through the roof. The heat flux into the bottom layer was used as an estimate of the heat flux into the building. The mean daytime heat flux (1200-2000 PST) under the exposed roof in the model was 14.0 Watts per square meter larger than under the tilted PV array. The maximum downward heat flux was 18.7 Watts per square meters for the exposed roof and 7.0 Watts per square meters under the tilted PV array, a 63% reduction due to the PV array. This study is unique as the impact of tilted and flush PV arrays could be compared against a typical exposed roof at the same roof for a commercial uninhabited building with exposed ceiling and consisting only of the building envelope. Our results indicate a more comfortable indoor environment in PV covered buildings without HVAC both in hotter and cooler seasons.
Dominguez, A.; Klessl, J.; Samady, M.; Luvall, J. C.
Investigation of Fundamental Modeling and Thermal Performance Issues for a Metallic Thermal Protection System Design
A study was performed to develop an understanding of the key factors that govern the performance of metallic thermal protection systems for reusable launch vehicles. A current advanced metallic thermal protection system (TPS) concept was systematically analyzed to discover the most important factors governing the thermal performance of metallic TPS. A large number of relevant factors that influence the thermal analysis and thermal performance of metallic TPS were identified and quantified. Detailed finite element models were developed for predicting the thermal performance of design variations of the advanced metallic TPS concept mounted on a simple, unstiffened structure. The computational models were also used, in an automated iterative procedure, for sizing the metallic TPS to maintain the structure below a specified temperature limit. A statistical sensitivity analysis method, based on orthogonal matrix techniques used in robust design, was used to quantify and rank the relative importance of the various modeling and design factors considered in this study. Results of the study indicate that radiation, even in small gaps between panels, can reduce significantly the thermal performance of metallic TPS, so that gaps should be eliminated by design if possible. Thermal performance was also shown to be sensitive to several analytical assumptions that should be chosen carefully. One of the factors that was found to have the greatest effect on thermal performance is the heat capacity of the underlying structure. Therefore the structure and TPS should be designed concurrently.
Blosser, Max L.
Building roof modeling from airborne laser scanning data based on level set approach
This paper presents a novel approach to building roof modeling, including roof plane segmentation and roof model reconstruction, from airborne laser scanning data. Segmentation is performed by minimizing an energy function formulated as multiphase level set. The energy function is minimized when each segment corresponds to one or several roof plans of the same normal vector. With this formulation, maximum n regions are segmented at a time by applying log2n level set functions. The roof ridges or step edges are then delineated by the union of the zero level contours of the level set functions. In the final step of segmentation, coplanar and parallel roof segments are separated into individual roof segments based on their connectivity and homogeneity. To reconstruct a 3D roof model, roof structure points are determined by intersecting adjacent roof segments or line segments of building boundary and then connected based on their topological relations inferred from the segmentation result. As a global solution to the segmentation problem, the proposed approach determines multiple roof segments at the same time, which leads to topological consistency among the segment boundaries. The paper describes the principle and solution of the multiphase level set approach and demonstrates its performance and properties with two airborne laser scanning data sets.
Kim, KyoHyouk; Shan, Jie
Space Shuttle Orbiter - Reusable surface insulation subsystem thermal performance
The thermal performance of the reusable surface insulation (RSI) subsystem consisting of silica tiles, silicone coated nylon felt insulation, and ceramic cloth gap fillers and thermal barriers is discussed. Thermal response predictions for the components are compared with measured flight data, which indicates that the RSI thermal performance can meet or exceed design requirements for the majority of the RSI. Visual inspections and the maximum temperature conditions observed in structural components after data acquisition suggest that the flight environment was not as severe as the worst case preflight prediction.
Dotts, R. L.; Battley, H. H.; Hughes, J. T.; Neuenschwander, W. E.
Joint Industry/Government Research Project: Comparison of thermal aging for roof exposures and thin-specimens of experimental polyisocyanurate insulation foamed with alternative blowing agents.
This paper reports apparent thermal conductivity (k) values from field exposures and laboratory aging of a set of industry-produced, experimental polyisocyanurate (PIR) laminated boardstock foamed with hydrochlorofluorocarbons (HCFCs) as alternative to ch...
R. S. Graves J. E. Christian D. L. McElroy
Advanced Low Conductivity Thermal Barrier Coatings: Performance and Future Directions
Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. In this presentation, thermal barrier coating development considerations and performance will be emphasized. Advanced thermal barrier coatings have been developed using a multi-component defect clustering approach, and shown to have improved thermal stability and lower conductivity. The coating systems have been demonstrated for high temperature combustor applications. For thermal barrier coatings designed for turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability. Erosion resistant thermal barrier coatings are being developed, with a current emphasis on the toughness improvements using a combined rare earth- and transition metal-oxide doping approach. The performance of the toughened thermal barrier coatings has been evaluated in burner rig and laser heat-flux rig simulated engine erosion and thermal gradient environments. The results have shown that the coating composition optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic durability. The erosion, impact and high heat-flux damage mechanisms of the thermal barrier coatings will also be described.
Zhu, Dongming; Miller, Robert A.
Predicted thermal performance of triple vacuum glazing
The simulated triple vacuum glazing (TVG) consists of three 4 mm thick glass panes with two vacuum gaps, with each internal glass surface coated with a low-emittance coating with an emittance of 0.03. The two vacuum gaps are sealed by an indium based sealant and separated by a stainless steel pillar array with a height of 0.12 mm and a pillar diameter of 0.3 mm spaced at 25 mm. The thermal transmission at the centre-of-glazing area of the TVG was predicted to be 0.26 W m{sup -2} K{sup -1}. The simulation results show that although the thermal conductivity of solder glass (1 W m{sup -1} K{sup -1}) and indium (83.7 W m{sup -1} K{sup -1}) are very different, the difference in thermal transmission of TVGs resulting from the use of an indium and a solder glass edge seal was 0.01 W m{sup -2} K{sup -1}. This is because the edge seal is so thin (0.12 mm), consequently there is a negligible temperature drop across it irrespective of the material that the seal is made from relative to the total temperature difference across the glazing. The results also show that there is a relatively large increase in the overall thermal conductance of glazings without a frame when the width of the indium edge seal is increased. Increasing the rebate depth in a solid wood frame decreased the heat transmission of the TVG. The overall heat transmission of the simulated 0.5 m by 0.5 m TVG was 32.6% greater than that of the 1 m by 1 m TVG, since heat conduction through the edge seal of the small glazing has a larger contribution to the total glazing heat transfer than that of the larger glazing system. (author)
Fang, Yueping; Hyde, Trevor J.; Hewitt, Neil [School of the Built Environment, University of Ulster, N. Ireland (United Kingdom)
ACCESS: thermal mechanical design and performance
Establishing improved spectrophotometric standards is important for a broad range of missions and is relevant to many astrophysical problems. ACCESS, "Absolute Color Calibration Experiment for Standard Stars", is a series of rocket-borne sub-orbital missions and ground-based experiments designed to enable improvements in the precision of the astrophysical flux scale through the transfer of absolute laboratory detector standards from the National Institute of Standards and Technology (NIST) to a network of stellar standards with a calibration accuracy of 1% and a spectral resolving power of 500 across the 0.35-1.7?m bandpass. Achieving a calibration accuracy of 1% not only requires an accurate calibration transfer from the detector standards to the instrument, but it also requires characterization and stability of the detector as well as a thermal background that contributes less than 1% to the flux per resolution element in the near-infrared (1.7?m) spectral region of the ACCESS bandpass. This paper describes the thermal mechanical design for achieving a low thermal background across the ACCESS spectral bandpass.
Kaiser, Mary E.; Morris, Matthew J.; Hansen, Jason; Jensen, Scott; McCandliss, Stephan R.; Rauscher, Bernard J.; Kimble, Randy A.; Kruk, Jeffrey W.; Pelton, Russell; Mott, D. Brent; Wen, Yiting; Gardner, Jonathan P.; Benford, Dominic J.; Woodgate, Bruce E.; Wright, Edward L.; Feldman, Paul D.; Moos, H. Warren; Riess, Adam G.; Bohlin, Ralph; Deustua, Susana E.; Dixon, W. V.; Sahnow, David J.; Kurucz, Robert; Lampton, Michael; Perlmutter, Saul
Thermal Performance of an Annealed Pyrolytic Graphite Solar Collector
A solar collector having the combined properties of high solar absorptance, low infrared emittance, and high thermal conductivity is needed for applications where solar energy is to be absorbed and transported for use in minisatellites. Such a solar collector may be used with a low temperature differential heat engine to provide power or with a thermal bus for thermal switching applications. One concept being considered for the solar collector is an Al2O3 cermet coating applied to a thermal conductivity enhanced polished aluminum substrate. The cermet coating provides high solar absorptance and the polished aluminum provides low infrared emittance. Annealed pyrolytic graphite embedded in the aluminum substrate provides enhanced thermal conductivity. The as-measured thermal performance of an annealed pyrolytic graphite thermal conductivity enhanced polished aluminum solar collector, coated with a cermet coating, will be presented.
Jaworske, Donald A.; Hornacek, Jennifer
Hydrological Modelling and Parameter Identification for Green Roof
Green roofs, a multilayered system covered by plants, can be used to replace traditional concrete roofs as one of various measures to mitigate the increasing stormwater runoff in the urban environment. Moreover, facing the high uncertainty of the climate change, the present engineering method as adaptation may be regarded as improper measurements; reversely, green roofs are unregretful and flexible, and thus are rather important and suitable. The related technology has been developed for several years and the researches evaluating the stormwater reduction performance of green roofs are ongoing prosperously. Many European counties, cities in the U.S., and other local governments incorporate green roof into the stormwater control policy. Therefore, in terms of stormwater management, it is necessary to develop a robust hydrologic model to quantify the efficacy of green roofs over different types of designs and environmental conditions. In this research, a physical based hydrologic model is proposed to simulate water flowing process in the green roof system. In particular, the model adopts the concept of water balance, bringing a relatively simple and intuitive idea. Also, the research compares the two methods in the surface water balance calculation. One is based on Green-Ampt equation, and the other is under the SCS curve number calculation. A green roof experiment is designed to collect weather data and water discharge. Then, the proposed model is verified with these observed data; furthermore, the parameters using in the model are calibrated to find appropriate values in the green roof hydrologic simulation. This research proposes a simple physical based hydrologic model and the measures to determine parameters for the model.
Lo, W.; Tung, C.
Evaluation of thermal protective performance of basalt fiber nonwoven fabrics
Thermal insulation and fire protection have been a point of interest and discussion for several decades. Due to its excellent\\u000a performances, basalt fiber has been widely used in the fields of thermal insulation and fire protection. The morphological\\u000a structure and thermal stability of continuous basalt fiber were analysed using CH-2 projection microscope, scanning electron\\u000a microscope (SEM) and thermogravimetry (TG). In
L. C. Hao; W. D. Yu
Drying of an AAC flat roof in different climates. Computational sensitivity analysis versus material property measurements
1. The Problem To protect a flat roof from interstitial condensation, a vapour retarder is required in cold climates. However, in the case of an autoclaved aerated concrete (AAC) roof a vapour retarder would also prevent the construction moisture from drying, and thereby, severely impair the thermal insulation quality of the AAC. In order to find out whether an unvented
Andreas Holm
Thermal deformation impacts on SOG Fresnel lens performance
Silicone-on-Glass (SOG) Fresnel lenses are flat optical elements used in concentrator photovoltaics (CPV). SOG lens production process broadly involves forming optical silicone prisms attached to glass. Silicone is first compressed onto glass while heat is applied in order to shorten its curing time. During the cooling process, however, difference between thermal expansion coefficient for silicon and glass causes thermal deformation of prisms which results in compromised optical efficiency. In this study, thermal-induced deformation of SOG Fresnel lens prisms is analyzed by Surface Profile Measurement (SPM) and Finite Element Analysis (FEA) methods. In order to better observe patterns of thermal deformation and overall lens performance, lens samples were subjected to an optical efficiency test. Focus quality (FQ) images were also taken and observed in order to further analyze thermally affected lens performance. The study is expected to contribute to knowledge on temperature induced performance determinants of SOG Fresnel lenses.
B�y�kco?kun, Murat; Annen, Hans Philipp; Gonz�lez Mu�oz, Luis Felipe
Thermal performance of concrete masonry unit wall systems
New materials, modern building wall technologies now available in the building marketplace, and unique, more accurate, methods of thermal analysis of wall systems create an opportunity to design and erect buildings where thermal envelopes that use masonry wall systems can be more efficient. Thermal performance of the six masonry wall systems is analyzed. Most existing masonry systems are modifications of technologies presented in this paper. Finite difference two-dimensional and three-dimensional computer modeling and unique methods of the clear wall and overall thermal analysis were used. In the design of thermally efficient masonry wall systems is t to know how effectively the insulation material is used and how the insulation shape and its location affect the wall thermal performance. Due to the incorrect shape of the insulation or structural components, hidden thermal shorts cause additional heat losses. In this study, the thermal analysis of the clear wall was enriched with the examination of the thermal properties of the wall details and the study of a quantity defined herein the Thermal Efficiency of the insulation material.
Kosny, J.
Adaptive Thermal Management for High-Performance Microprocessors
With the increasing clock rate and transistor count of today's microprocessors, power dissipation is becoming a critical component of system design complexity. Thermal and power-delivery issues related to the maximum power dissipation are becoming especially critical for high-performance computing systems. In this work, we investigate dynamic thermal management as a technique to control CPU power dissipation. With the increasing usage
David Brooks; Margaret Martonosi
High Performance Lightweight Compact Thermal Radiator For Space Vehicles
A unique and novel feature invention titled as ``High performance lightweight compact thermal radiator'' was filed on March 31, 2005. This new invention utilizes the superb isotropic higher thermal conductivity of industrial Chemical Vapor Deposition (CVD) diamond or diamond composite as face sheet material. In addition, carbon foam panel or carbon graphite composite panel is also used as the radiator
Ching-Fen Tsai; Julian Prabhu; Frank Shen
Thermal performance of an elliptical pin fin heat sink
Comparative thermal tests have been carried out using, aluminum heat sinks made with extruded fin, cross-cut rectangular pins, and elliptical shaped pins in low air flow environments. The elliptical pin heat sink was designed to minimize the pressure loss across the heat sink by reducing the vortex effects and to enhance the thermal performance by maintaining large exposed surface area
Christopher L. Chapman; Seri Lee; Bill L. Schmidt
The effect of thermal barrier coatings on diesel engine performance
An experimental study of the effects of thin thermal barrier coatings on the performance of a diesel engine was conducted. Results obtained from the engine with thermally insulated pistons were compared with the baseline engine data. Engine trials demonstrated good properties of both coating systems. Temperature and stress distributions within the pistons were evaluated analytically by means of the Cosmos\\/Works
T. Hejwowski; A. Wero?ski
Performance evaluation of molten salt thermal storage systems
The molton salt thermal storage system located at the Central Receiver Test Facility (CRTF) was recently subjected to thermal performance tests. The system is composed of a hot storage tank containing molten nitrate salt at a temperature of 1050 F and a cold tank containing 550 F salt with associated valves and controls. It is rated at 7 MWht and
G. J. Kolb; U. Nikolai
Flight performance: Frigatebirds ride high on thermals
Aspects of the morphology and life history of frigatebirds verge on the extreme, and how they spend their time at sea has been a mystery until now. Here we use data collected by altimeters and satellite transmitters attached to individual frigatebirds to show that these birds are continuously on the wing, day and night - they fly in a succession of climbs and descents, soaring in circles on thermals to heights of up to 2,500 m and gliding down in the direction of travel. The birds' curious morphology and flight patterns result in extremely low costs of foraging, but they also cause them to travel slowly over large distances, putting frigatebirds at an evolutionary extreme that enables them to exploit tropical waters in which prey is scarce.
Weimerskirch, Henri; Chastel, Olivier; Barbraud, Christophe; Tostain, Olivier
Thermal Components Boost Performance of HVAC Systems
As the International Space Station (ISS) travels 17,500 miles per hour, normal is having a constant sensation of free-falling. Normal is no rain, but an extreme amount of shine.with temperatures reaching 250 F when facing the Sun. Thanks to a number of advanced control systems onboard the ISS, however, the interior of the station remains a cool, comfortable, normal environment where astronauts can live and work for extended periods of time. There are two main control systems on the ISS that make it possible for humans to survive in space: the Thermal Control System (TCS) and the Environmental Control and Life Support system. These intricate assemblies work together to supply water and oxygen, regulate temperature and pressure, maintain air quality, and manage waste. Through artificial means, these systems create a habitable environment for the space station s crew. The TCS constantly works to regulate the temperature not only for astronauts, but for the critical instruments and machines inside the spacecraft as well. To do its job, the TCS encompasses several components and systems both inside and outside of the ISS. Inside the spacecraft, a liquid heat-exchange process mechanically pumps fluids in closed-loop circuits to collect, transport, and reject heat. Outside the ISS, an external system circulates anhydrous ammonia to transport heat and cool equipment, and radiators release the heat into space. Over the years, NASA has worked with a variety of partners.public and private, national and international. to develop and refine the most complex thermal control systems ever built for spacecraft, including the one on the ISS.
Parametric Study of Solar Thermal Rocket Nozzle Performance.
This paper details a numerical investigation of performance losses in low-thrust solar thermal rocket nozzles. The effects of nozzle geometry on three types of losses were studied; finite rate dissociation-recombination kinetic losses, two dimensional axi...
J. B. Pearson D. B. Landrum C. W. Hawk
The molton salt thermal storage system located at the Central Receiver Test Facility (CRTF) was recently subjected to thermal performance tests. The system is composed of a hot storage tank containing molten nitrate salt at a temperature of 1050/sup 0/F and a cold tank containing 550/sup 0/F salt with associated valves and controls. It is rated at 7 MWht and was designed and installed by Martin Marietta Corporation in 1982. The results of these tests were used to accomplish four objectives: (1) to compare the current thermal performance of the system with the performance of the system soon after it was installed, (2) to validate a dynamic computer model of the system, (3) to obtain an estimate of an annual system efficiency for a hypothetical commercial scale 1200 MWht system and (4) to compare the performance of the CRTF system with thermal storage systems developed by the European solar community. 4 refs., 4 figs., 2 tabs.
Kolb, G.J.; Nikolai, U.
Predicting the physiological performance of ectotherms in fluctuating thermal environments.
Physiological ecologists have long sought to understand the plasticity of organisms in environments that vary widely among years, seasons and even hours. This is now even more important because human-induced climate change is predicted to affect both the mean and variability of the thermal environment. Although environmental change occurs ubiquitously, relatively few researchers have studied the effects of fluctuating environments on the performance of developing organisms. Even fewer have tried to validate a framework for predicting performance in fluctuating environments. Here, we determined whether reaction norms based on performance at constant temperatures (18, 22, 26, 30 and 34�C) could be used to predict embryonic and larval performance of anurans at fluctuating temperatures (18-28�C and 18-34�C). Based on existing theory, we generated hypotheses about the effects of stress and acclimation on the predictability of performance in variable environments. Our empirical models poorly predicted the performance of striped marsh frogs (Limnodynastes peronii) at fluctuating temperatures, suggesting that extrapolation from studies conducted under artificial thermal conditions would lead to erroneous conclusions. During the majority of ontogenetic stages, growth and development in variable environments proceeded more rapidly than expected, suggesting that acute exposures to extreme temperatures enable greater performance than do chronic exposures. Consistent with theory, we predicted performance more accurately for the less variable thermal environment. Our results underscore the need to measure physiological performance under naturalistic thermal conditions when testing hypotheses about thermal plasticity or when parameterizing models of life-history evolution. PMID:22279077
Niehaus, Amanda C; Angilletta, Michael J; Sears, Michael W; Franklin, Craig E; Wilson, Robbie S
The author compares the thermal performance of multi-chip modules (MCMs) based on their interconnection technology. The comparisons were made for hermetic and conduction cooled use environments. The thermal performances of the chip-first high-density interconnect (HDI) technology, the flipped-chip (FC) technology, and flipped-tape automated bonding (FTAB) technologies were analyzed and compared for MCM applications. The results of the study showed the
Thermal Performance of Surface Wick Structures
Microscale surface wick structures that exploit capillary driven flow in interior corners have been designed. In this study we examine the interplay between capillary flow and evaporative heat transfer that effectively reduces the surface temperature. The tests are performed by raising the surface temperature to various levels before the flow is introduced to the surfaces. Certainly heat transfer weakens the
Yongkang Chen; Noel Tavan; John Baker; Lawrence Melvin; Mark Weislogel
ATST enclosure: seeing performance, thermal modeling, and error budgets
The enclosure for the Advanced Technology Solar Telescope (ATST) is both a wind shield and a source of seeing. Its design must minimize self-induced seeing while remaining within cost constraints and balancing with other error budget items. We report the methods used to quantify seeing performance, including thermal modeling, seeing estimation, and systems engineering error budgets. Thermal modeling is performed using a commercial software package that applies measured site weather data to a CAD-generated enclosure model. Seeing estimation is performed using a simple aerodynamic treatment. The results, along with measured site wind and temperature distributions, are combined into a "bottom-up" performance prediction using Monte Carlo techniques.
Dalrymple, Nathan E.; Oschmann, Jacobus M., Jr.; Hubbard, Robert P.
Green roof soil system affected by soil structural changes: A project initiation
Anthropogenic soil systems and structures such as green roofs, permeable or grassed pavements comprise appreciable part of the urban watersheds and are considered to be beneficial regarding to numerous aspects (e.g. carbon dioxide cycle, microclimate, reducing solar absorbance and storm water). Expected performance of these systems is significantly affected by water and heat regimes that are primarily defined by technology and materials used for system construction, local climate condition, amount of precipitation, the orientation and type of the vegetation cover. The benefits and potencies of anthropogenic soil systems could be considerably threatened in case when exposed to structural changes of thin top soil layer in time. Extensive green roof together with experimental green roof segment was established and advanced automated monitoring system of micrometeorological variables was set-up at the experimental site of University Centre for Energy Efficient Buildings as an interdisciplinary research facility of the Czech Technical University in Prague. The key objectives of the project are (i) to characterize hydraulic and thermal properties of soil substrate studied, (ii) to establish seasonal dynamics of water and heat in selected soil systems from continuous monitoring of relevant variables, (iii) to detect structural changes with the use of X-ray Computed Tomography, (iv) to identify with the help of numerical modeling and acquired datasets how water and heat dynamics in anthropogenic soil systems are affected by soil structural changes. Achievements of the objectives will advance understanding of the anthropogenic soil systems behavior in conurbations with the temperate climate.
Jel�nkov�, Vladim�ra; Dohnal, Michal; ��cha, Jan; �ebestov�, Jana; Sn?hota, Michal
Automated roof identification systems and methods
US Patent & Trademark Office Database
Automatic roof identification systems and methods are described. Example embodiments include a roof estimation system configured to automatically detect a roof in a target image of a building having a roof. In one embodiment, automatically detecting a roof in a target image includes training one or more artificial intelligence systems to identify likely roof sections of an image. The artificial intelligence systems are trained on historical image data or an operator-specified region of interest within the target image. Then, a likely outline of the roof in the target image can be determined based on the trained artificial intelligence systems. The likely roof outline can be used to generate a roof estimate report. This abstract is provided to comply with rules requiring an abstract, and it is submitted with the intention that it will not be used to interpret or limit the scope or meaning of the claims.
Thermal performance of packed-bed solar air heaters
This paper presents an experimental investigation of the enhancement of thermal performance of solar iar heater having its duct packed with blackened wire-screen matrices. Tests were conducted to cover wide range of influencing parameters including geometry of wire screens, mass flow rates and input solar energy fluxes under actual outdoor conditions. Effect of these parameters on the thermal performance has been investigated and results have been compared with those of plane (flat-plate) collectors. These tests provide useful data for rating wire-screen matrices packed-bed collectors based on thermal performance. It is observed that the performance of plane collector improves appreciably by packing its duct with blackened wire-screen matrices and this improvement is a strong function of bed and operating parameters.
Sharma, S.P.; Saini, J.S.; Varma, H.K. (Univ. of Roorkee (India))
Thermal performance of a double-envelope house
An evaluation is made of the thermal performance of a double envelope house of Ekose's design built in Middletown, Rhode Island. Performance monitoring in the heating season showed that the requirements for auxiliary heat are very low, about 2.1 Btu per square foot or floor space per degree day. Design changes are identified which could reduce the heating needs of
G. Dennehy; R. F. Jones
Thermal Performance Analysis of a Double-Envelope House.
An evaluation is made of the thermal performance of a double-envelope house of Ekose'a design built in Middletown, Rhode Island. Performance monitoring in the heating season showed that the requirements for auxiliary heat are very low, about 2.1 Btu per s...
G. Dennehy R. F. Jones
LCD display screen performance testing for handheld thermal imaging cameras
Handheld thermal imaging cameras are an important tool for the first responder community. As their use becomes more prevalent, it will become important for a set of standard test metrics to be available to characterize the performance of these cameras. A major factor in the performance of the imagers is the quality of the image on a display screen. An
Joshua B. Dinaburg; Francine Amon; Anthony Hamins; Paul Boynton
EMC effects of the lightning protection system: shielding properties of the roof-grid
A suitable set of parameters is used to evaluate the shielding performance of the roof-grid constituted by a mesh of conductors, electrically interconnected, laying on top of buildings with a large-area roof. The influence of the roof-grid on the electromagnetic field inside the building due to a direct lightning strike is shown. The values of the electromotive force induced in
S. Cristina; A. Orlandi
Infrared thermal detectors versus photon detectors: I. Pixel performance
Investigations of the performance of IR thermal detectors as compared to photon detectors are presented. Due to fundamental different types of noise, these two classes of detectors have different dependencies of detectivities on wavelength and temperature. The photon detectors are favored at long wavelength IR and lower operating temperatures. The thermal detectors are favored at very long wavelength spectral range. The comparative studies of the thermal detectors with HgCdTe photodiodes, doped silicon detectors and quantum well IR photodetectors are carried out. In comparison with Kruse's paper these studies are re-examined taking into account updated theories of different types of detectors. The considerations are made for different background levels.
Rogalski, Antoni
The Effect of Thermal Loading on Laboratory Fume Hood Performance
A modified version of the ANSI\\/ASHRAE 110-1995 Method of Testing Performance of Laboratory Fume Hoods was used to evaluate the relationship between thermal loading in a laboratory fume hood and subsequent tracer gas leakage. Three types of laboratory burners were used, alone and in combination, to thermally challenge the hood. Heat output from burners was measured in BTU\\/hr, which was
James D. Johnston; Saul J. Chessin; Brian W. Chesnovar; Dean R. Lillquist
Thermal performance of an envelope house in a cold climate
Presented are thermal performance data on a double-shell or envelope passive solar residence. The space between the inner and outer shell was instrumented with home-made heated anemometers that were sensitive to air flows in the 0 to 0.5 m-sec⁻¹ range. A partitioned heat balance on the inner and outer shell allowed conclusions to be drawn about the relative thermal contributions
Thermal Performance Testing of EMU and OSS Liquid Cooling Garments
A test was conducted to evaluate three factors influencing the thermal performance of liquid cooling garments (LCG): (1) the comparable thermal performance of an Oceaneering developed engineering evaluation unit (EEU) prototype LDG, (2) the effect of the thermal comfort undergarment (TCU), and (3) the performance of a torso or upper body only LCG configuration. To evaluate the thermal performance of each configuration a metabolic test was conducted, utilizing suited subjects to generate the metabolic heat. For this study three (3) test subjects of similar health and weight produced a metabolic load on the LDG configuration by either resting (300-600 BTU/hr), walking at a slow pace (1200 BRU/hr), and walking at a brisk pace (2200 BTU/hr), as outlined in Figure 1, the metabolic profile. During the test, oxygen consumption, heart rate, relative humidity, air flow, inlet and outlet air pressure, inlet and outlet air temperature, delta air temperature, water flow (100 lb/hr), inlet water temperature (64 F), delta water temperature, water pressure, core body temperature, skin temperature, and sweat loss data was recorded. Four different test configurations were tested, with one configuration tested twice, as outlined in Table 1. The test was conducted with the suit subjects wearing the Demonstrator Suit, pressurized to vent pressure (approximately 0.5 psig). The demonstrator suit has an integrated ventilation duct system and was used to create a relevant environment with a captured ventilation return, an integrated vent tree, and thermal insulation from the environment.
Rhodes, Richard; Bue, Grant; Hakam, Mary
Duct thermal performance models for large commercial buildings
Despite the potential for significant energy savings by reducing duct leakage or other thermal losses from duct systems in large commercial buildings, California Title 24 has no provisions to credit energy-efficient duct systems in these buildings. A substantial reason is the lack of readily available simulation tools to demonstrate the energy-saving benefits associated with efficient duct systems in large commercial buildings. The overall goal of the Efficient Distribution Systems (EDS) project within the PIER High Performance Commercial Building Systems Program is to bridge the gaps in current duct thermal performance modeling capabilities, and to expand our understanding of duct thermal performance in California large commercial buildings. As steps toward this goal, our strategy in the EDS project involves two parts: (1) developing a whole-building energy simulation approach for analyzing duct thermal performance in large commercial buildings, and (2) using the tool to identify the energy impacts of duct leakage in California large commercial buildings, in support of future recommendations to address duct performance in the Title 24 Energy Efficiency Standards for Nonresidential Buildings. The specific technical objectives for the EDS project were to: (1) Identify a near-term whole-building energy simulation approach that can be used in the impacts analysis task of this project (see Objective 3), with little or no modification. A secondary objective is to recommend how to proceed with long-term development of an improved compliance tool for Title 24 that addresses duct thermal performance. (2) Develop an Alternative Calculation Method (ACM) change proposal to include a new metric for thermal distribution system efficiency in the reporting requirements for the 2005 Title 24 Standards. The metric will facilitate future comparisons of different system types using a common ''yardstick''. (3) Using the selected near-term simulation approach, assess the impacts of duct system improvements in California large commercial buildings, over a range of building vintages and climates. This assessment will provide a solid foundation for future efforts that address the energy efficiency of large commercial duct systems in Title 24. This report describes our work to address Objective 1, which includes a review of past modeling efforts related to duct thermal performance, and recommends near- and long-term modeling approaches for analyzing duct thermal performance in large commercial buildings.
Wray, Craig P.
Self advancing mine roof supports
A self-advancing mine-roof-support for use in or aligned with a main roadway or gate has a floor-engaging part and a roof engaging part spaced apart by extensible load-bearing prop or jack means, and engagement means for a face-conveyor and a transversely acting transfer conveyor whereby their relative positions are constrained to facilitate discharge of mineral from one conveyor to the other. The engagement means for the face conveyor comprises sliding anchor beams that assure maintenance of the relative attitudes of the support and the face conveyor and the transfer conveyor is held fore and aft of the support.
Seddon, J.; Jones, F.
Portable Life Support Subsystem Thermal Hydraulic Performance Analysis
This paper presents the current state of the thermal hydraulic modeling efforts being conducted for the Constellation Space Suit Element (CSSE) Portable Life Support Subsystem (PLSS). The goal of these efforts is to provide realistic simulations of the PLSS under various modes of operation. The PLSS thermal hydraulic model simulates the thermal, pressure, flow characteristics, and human thermal comfort related to the PLSS performance. This paper presents modeling approaches and assumptions as well as component model descriptions. Results from the models are presented that show PLSS operations at steady-state and transient conditions. Finally, conclusions and recommendations are offered that summarize results, identify PLSS design weaknesses uncovered during review of the analysis results, and propose areas for improvement to increase model fidelity and accuracy.
Barnes, Bruce; Pinckney, John; Conger, Bruce
Thermal performance modeling of NASA s scientific balloons
The flight performance of a scientific balloon is highly dependant on the interaction between the balloon and its environment. The balloon is a thermal vehicle. Modeling a scientific balloon's thermal performance has proven to be a difficult analytical task. Most previous thermal models have attempted these analyses by using either a bulk thermal model approach, or by simplified representations of the balloon. These approaches to date have provided reasonable, but not very accurate results. Improvements have been made in recent years using thermal analysis tools developed for the thermal modeling of spacecraft and other sophisticated heat transfer problems. These tools, which now allow for accurate modeling of highly transmissive materials, have been applied to the thermal analysis of NASA's scientific balloons. A research effort has been started that utilizes the "Thermal Desktop" addition to AUTO CAD. This paper will discuss the development of thermal models for both conventional and Ultra Long Duration super-pressure balloons. This research effort has focused on incremental analysis stages of development to assess the accuracy of the tool and the required model resolution to produce usable data. The first stage balloon thermal analyses started with simple spherical balloon models with a limited number of nodes, and expanded the number of nodes to determine required model resolution. These models were then modified to include additional details such as load tapes. The second stage analyses looked at natural shaped Zero Pressure balloons. Load tapes were then added to these shapes, again with the goal of determining the required modeling accuracy by varying the number of gores. The third stage, following the same steps as the Zero Pressure balloon efforts, was directed at modeling super-pressure pumpkin shaped balloons. The results were then used to develop analysis guidelines and an approach for modeling balloons for both simple first order estimates and detailed full models. The development of the radiative environment and program input files, the development of the modeling techniques for balloons, and the development of appropriate data output handling techniques for both the raw data and data plots will be discussed. A general guideline to match predicted balloon performance with known flight data will also be presented. One long-term goal of this effort is to develop simplified approaches and techniques to include results in performance codes being developed.
Franco, H.; Cathey, H.
Performance of thermal conductivity probes for planetary applications
This work aims to contribute to the development of in situ instruments feasible for space application. Commercial as well as custom made thermal sensors, based on the transient hot wire technique and suitable for direct measurement of the effective thermal conductivity of granular media, were tested for application under airless conditions. The investigated media range from compact specimen of well known thermal conductivity used for calibration of the sensors to various granular planetary analogue materials of different shape and grain size. Measurements were performed under gas pressures ranging from 103 hPa down to about 10-5 hPa. It was found that for the inspected granular materials the given pressure decrease results in a decrease of the thermal conductivity by about two orders of magnitude. In order to check the ability of custom-made sensors to measure the thermal conductivity of planetary surface layers, detailed numerical simulations predicting the response of the different sensors have also been performed. Both, measurements and simulations, revealed that for investigations under high vacuum conditions (as they prevail e.g. on the lunar surface) the derived thermal conductivity values can significantly depend on the sensor geometry, the axial heat flow and the thermal contact between probe and surrounding material. Therefore in these cases a careful calibration of each particular sensor is necessary in order to obtain reliable thermal conductivity measurements. The custom-made sensors presented in this work can serve as prototypes for payload to be flown on future planetary lander missions, in particular for airless bodies like the Moon, asteroids and comets, but also for Mars.
H�tter, E. S.; K�mle, N. I.
Field Investigation of Externally Insulated Sheeting Roofs.
This investigation of externally insulated sheeting roofs comprised field investigations in addition to the tests in the laboratory. The field investigation consisted of collection of insulation and sheeting data from roof laying in progress, and the proc...
B. Gullbrandson G. Johansson
Measured performance of a solar augmented heat pump/chiller system with thermal storage in tanks of stratified water
The performance of the heating and cooling system in a building designed to illustrate energy conservation, solar energy use and thermal storage for electric load management and energy conservation was monitored for a period of 20 months, beginning in January 1981. Solar energy was employed to augment the heating energy obtained by heat recovery using electric-driven reciprocating heat pump/chillers and an air-to-air heat exchanger. Solar energy was gathered by 289 m/sup 2/ (3110 ft/sup 2/) of evacuated tube collectors on the roof of the building, which has a gross floor area of 5330 m/sup 2/ (57,350 ft/sup 2/). The fractions of the total active heating load, including air-to-air heat recovery, supplied by solar energy for the one partial and one completed heating season for which results were obtained, were 50 and 42 percent, respectively. Stratified water tanks were used in the heating season to store excess solar energy and both heating and cooling capacity generated by the heat pump/chillers. During the cooling season, the tanks were used to store cooling capacity generated by the chillers. An economic analysis using the results for energy consumption obtained from this building indicated that the solar system was not economically attractive, despite its encouraging technical performance. Thermal storage for electric load management was attractive for moderate costs of capital.
Wildin, M.W.
Integrated heat pipe-thermal storage system performance evaluation
An integrated thermal energy storage (TES) system, developed as a part of an organic Rankine cycle solar dynamic power system is described, and the results of the performance verification tests of this TES system are presented. The integrated system consists of potassium heat-pipe elements that incorporate TES canisters within the vapor space, along with an organic fluid heater tube used as the condenser region of the heat pipe. The heat pipe assembly was operated through the range of design conditions from the nominal design input of 4.8 kW to a maximum of 5.7 kW. The performance verification tests show that the system meets the functional requirements of absorbing the solar energy reflected by the concentrator, transporting the energy to the organic Rankine heater, providing thermal storage for the eclipse phase, and allowing uniform discharge from the thermal storage to the heater.
Keddy, E.; Sena, J. T.; Merrigan, M.; Heidenreich, Gary
Optical performance of bimetallic mirrors under thermal environment
Evaluation of the optical performances of bimetallic mirrors with various substrate shapes was conducted using the finite element analysis program, SDRC-IDEAS. In these analyses, two different plating materials, nickel and aluminum were considered for an aluminum and a beryllium mirror substrate. Thermal environment used in this study is a unit thermal soak. Surface errors, individual aberration terms, such as piston, tilts, focus and other aberrations were obtained by the program PCFRINGE. It was found that the optical performances of bimetallic mirrors depend on the polating material, plating thickness, and the mirror substrate shapes materials. The optimum plating thickness combinations were determined based on plating material and mirror substrate with temperature difference. The results were compared with the optical surface errors and the corrected surface errors. The results indicate that there does not exist a definitive common rule for the optimum, but a detailed analysis such as presented herein is generally needed to design bimetallic mirrors in a thermal environment.
Moon, Il K.; Cho, Myung K.; Richard, Ralph M.
Optimization of the Thermal Performance of Microchannel Heat Sinks Using Thermally Developing Nusselt Number Correlation
One-dimensional (1-D) thermal resistance model has been shown in various works to be a computationally economical alternative to the full three-dimensional (3-D) conjugate heat transfer analysis achievable by computational fluid dynamics (CFD) codes for evaluating the thermal performance of microchannel heat sinks. This simplified 1-D approach is often exploited to obtain the optimum microchannel geometry that would give rise to
P. S. Lee; S. K. Chou; Y. J. Lee
Performance issues in solar thermal energy transport systems
Pacific Northwest Laboratory, sponsored by the US Department of Energy through Sandia National Laboratories, is performing an assessment of three solar thermal electricity generating concepts; central receivers, dishes, and troughs. Concepts are being studied over a range of system sizes 0.5 MWe to 100 MWe with solar multiples from 1.0 to 2.8. Central receiver systems using molten salt, sodium, and water-steam working fluids are studied. The dish system selected for study uses a kinematic Stirling engine at the focal point, and the trough system is based on Accurex designed collectors heating a heat transfer oil. Of the three concepts studied, the central receiver and trough systems utilize thermal transport systems. A thermal transport system is the piping and fluid required to transfer thermal energy between receiver, and storage and between storage and steam generator. The literature contains many transport system designs, most of which are optimized with regard to cost and performance. We used the parameters specified from the optimizations to design our systems and scale the designs over the 0.5 MWe to 100 MWe size range. From these designs, thermal losses and pump sizes are derived then combined in a system model to obtain total annual averaged efficiency as a function of plant field size. We found that central receiver transport efficiency improves with field size whereas trough transport efficiency degrades with field size. We found that overnight cooldown accounts for roughly 50% of the total thermal losses for all transport systems. Trough performance is substantially degraded because the receiver tubes are not drained which allows a large overnight heat loss. Trough transport performance was found to be sensitive to fluid velocity.
Zimmerman, P. W.
Comparative performance of solar thermal power generation concepts
A performance comparison is made between the central receiver system (power tower) and a distributed system using either dishes or troughs and lines to transport fluids to the power station. These systems were analyzed at a rated capacity of 30 MW of thermal energy delivered in the form of superheated steam at 538 C (1000 F) and 68 atm (1000 psia), using consistent weather data, collector surface waviness, pointing error, and electric conversion efficiency. The comparisons include technical considerations for component requirements, land utilization, and annual thermal energy collection rates. The relative merits of different representative systems are dependent upon the overall conversion as expressed in the form of performance factors in this paper. These factors are essentially indices of the relative performance effectiveness for different concepts based upon unit collector area. These performance factors enable further economic tradeoff studies of systems to be made by comparing them with projected production costs for these systems.
Wen, L.; Wu, Y. C.
The Thermal Performance of a Two-Bedroom Mobile Home.
Tests were conducted on a mobile home located in an Environmental Climatic Laboratory for the purpose of evaluating its thermal performance. The heating demand greatly affected the part-load efficiency of a gas-fired, forced-air, sealed-combustion furnace...
G. J. Teitsma B. A. Peavy
Tests were conducted on a mobile home located in an Environmental Climatical Laboratory for the purpose of evaluating its thermal performance. The heating demand greatly affected the part-load efficiency of a gas-fired, forced-air, sealed-combustion furna...
G. J. Tietsma B. A. Peavy
Method of measuring thermal conductivity of high performance insulation
Method accurately measures the thermal conductivity of high-performance sheet insulation as a discrete function of temperature. It permits measurements to be made at temperature drops of approximately 10 degrees F across the insulation and ensures measurement accuracy by minimizing longitudinal heat losses in the system.
Hyde, E. H.; Russell, L. D.
Cost and performance evaluation of terrestrial solar thermal power systems
A cost optimization model was developed based on relating systems costs to performance and minimizing the system electric energy production costs. The model was applied to systems representing major categories of solar thermal power systems such as the central receiver, the parabolic dish, the line-focusing and the fixed orientation focusing collectors. Several types of engines and energy storage systems were
N. Elgabalawi
A thorough evaluation of cost and performance of solar thermal power systems is required in order to assess the viability of such systems for commercial applications, particularly before the commitment of large investments to the manufacture of particular systems. Optimization and simulation models can be effectively used for the evaluation and analysis of several varieties of these systems. A cost
El Gabalawi
Thermal Performance Analysis of the Lithium-Ion Batteries
Heat was produced during the charge or discharge process. The performances and circle life will be seriously affected if the heat can not be dissipated immediately. Base on the models and theories of the batteries, analytical solution has been obtained conditioned on certain assumptions with the method of thermal-electrochemical model. According to the optimized chemical model, temperature distribution has been
Mao-de Li; Feng Wang
Performance evaluation of solar photovoltaic\\/thermal systems
The major purpose of the present study is to understand the performance of an integrated photovoltaic and thermal solar system (IPVTS) as compared to a conventional solar water heater and to demonstrate the idea of an IPVTS design. A commercial polycrystalline PV module is used for making a PV\\/T collector. The PV\\/T collector is used to build an IPVTS. The
B. J Huang; T. H Lin; W. C Hung; F. S Sun
Polymer gear surface thermal wear and its performance prediction
This paper will concentrate on acetal gear wear behaviour and its performance prediction based on the extensive investigations on the gear thermal mechanical contact both experimentally and numerically. It has been found from the tests that acetal gear wear rate will be increased dramatically when the load reaches a critical value for a specific geometry and running speed. The gear
K. Mao; W. Li; C. J. Hooke; D. Walton
Thermal performance analysis of a double-envelope house
An evaluation is made of the thermal performance of a double-envelope house of Ekose'a design built in Middletown, Rhode Island. Performance monitoring in the heating season showed that the requirements for auxiliary heat are very low, about 2.1 Btu per square foot of floor space per degree-day. Design changes are identified which could reduce the heating requirement even further. It
An evaluation is made of the thermal performance of a double envelope house of Ekose's design built in Middletown, Rhode Island. Performance monitoring in the heating season showed that the requirements for auxiliary heat are very low, about 2.1 Btu per square foot or floor space per degree day. Design changes are identified which could reduce the heating needs of the house are due primarily to the excellent insulative value of the double shell.
Dennehy, G.; Jones, R. F.
Liquid storage tank with floating roof structure
In a cylindrical wall storage tank for containing a liquid, said tank is described having a floor, a floatable roof supportable by said contained liquid, said roof including a peripheral seal for engaging the cylindrical wall to maintain a fluid-tight sliding seal therewith, and support means associated with said roof including, the improvement in said tank of, at least one
Floating roof tank with rim space seal
This patent describes a vertical cylindrical liquid storage tank having a circular floating roof of smaller diameter than the tank thereby defining a clearance space between the roof edge and the tank wall; a seal joined to the roof and extending upwardly therefrom into slidable contact with the tank wall; the seal completely covering the clearance space; the seal comprising
R. B. Grove; S. W. Peters; M. L. Tellalian
Code of Federal Regulations, 2011 CFR
...Standard Specification for Roof and Rock Bolts and Accessories,� the mine operator...the strata. (4) In each roof bolting cycle, the actual torque or tension of the...bolt installed during each roof bolting cycle shall be tested during or...
Code of Federal Regulations, 2012 CFR
Developing resilient green roofs in a dry climate.
Living roofs are an emerging green infrastructure technology that can potentially be used to ameliorate both climate change and urban heat island effects. There is not much information regarding the design of green roofs for dry climates and so the aim of this study was to develop low maintenance and unfertilized green roofs for a dry climate. This paper describes the effects of four important elements of green roofs namely slope, depth, growing media and plant species and their possible interactions in terms of plant growth responses in a dry climate. Sixteen medium-scale green roofs were set up and monitored during a one year period. This experiment consisted of twelve vegetated platforms and four non-vegetated platforms as controls. The design for the experiment was a split-split-plot design in which the factors Slope (1� and 25�) and Depth (100mm, 300mm) were randomized to the platforms (main plots). Root depth and volume, average height of plants, final dry biomass and ground cover, relative growth rate, final dry shoot-root ratio, water use efficiency and leaf succulence were studied during a twelve month period. The results showed little growth of the plants in media type A, whilst the growth was significant in both media types B and C. On average, a 90% survival rate of plants was observed. Also the growth indices indicated that some plants can grow efficiently in the harsh environment created by green roofs in a dry climate. The root growth pattern showed that retained water in the drainage layer is an alternative source of water for plants. It was also shown that stormwater can be used as a source of irrigation water for green roofs during six months of the year at the study site. In summary, mild sloping intensive systems containing media type C and planted with either Chrysocephalum apiculatum or Disphyma crassifolium showed the best performance. PMID:24880547
Razzaghmanesh, M; Beecham, S; Brien, C J
This work aims to contribute to the development of in situ instruments feasible for space application. Commercial as well as custom-made thermal sensors, based on the transient hot wire technique and suitable for direct measurement of the effective thermal conductivity of granular media, were tested for application under airless conditions. In order to check the ability of custom-made sensors to measure the thermal conductivity of planetary surface layers, detailed numerical simulations predicting the response of the different sensors have been performed. These simulations reveal that for investigations under high vacuum conditions (as they prevail, e.g. on the lunar surface), the derived thermal conductivity values can significantly depend on sensor geometry, axial heat flow, and the thermal contact between probe and surrounding material. Therefore, a careful calibration of each particular sensor is necessary in order to obtain reliable thermal conductivity measurements. The custom-made sensors presented in this work can serve as prototypes for payload to be flown on future planetary lander missions, in particular for airless bodies like the Moon, asteroids and comets, but also for Mars.
Floating-roof tank evaporation
The book describes an improved method for estimating the total evaporative losses of the equivalent atmospheric hydrocarbon emissions from external floating-roof tanks that contain multicomponent hydrocarbon mixtures (such as gasolines and crude oils) or single-component stocks (such as petro-chemicals).
Not Available
Performance of silvered Teflon (trademark) thermal control blankets on spacecraft
Silverized Teflon (Ag/FEP) is a widely used passive thermal control material for space applications. The material has a very low alpha/e ratio (less than 0.1) for low operating temperatures and is fabricated with various FEP thicknesses (as the Teflon thickness increases, the emittance increases). It is low outgassing and, because of its flexibility, can be applied around complex, curved shapes. Ag/FEP has achieved multiyear lifetimes under a variety of exposure conditions. This has been demonstrated by the Long Duration Exposure Facility (LDEF), Solar Max, Spacecraft Charging at High Altitudes (SCATHA), and other flight experiments. Ag/FEP material has been held in place on spacecraft by a variety of methods: mechanical clamping, direct adhesive bonding of tapes and sheets, and by Velcro(TM) tape adhesively bonded to back surfaces. On LDEF, for example, 5-mil blankets held by Velcro(TM) and clamping were used for thermal control over 3- by 4-ft areas on each of 17 trays. Adhesively bonded 2- and 5-mil sheets were used on other LDEF experiments, both for thermal control and as tape to hold other thermal control blankets in place. Performance data over extended time periods are available from a number of flights. The observed effects on optical properties, mechanical properties, and surface chemistry will be summarized in this paper. This leads to a discussion of performance life estimates and other design lessons for Ag/FEP thermal control material.
Pippin, Gary; Stuckey, Wayne; Hemminger, Carol
A Roof for ALMA
On 10 March, an official ceremony took place on the 2,900m high site of the Atacama Large Millimeter/submillimeter Array (ALMA) Operations Support Facility, from where the ALMA antennas will be remotely controlled. The ceremony marked the completion of the structural works, while the building itself will be finished by the end of the year. This will become the operational centre of one of the most important ground-based astronomical facilities on Earth. ESO PR Photo 13a/07 ESO PR Photo 13a/07 Cutting the Red Ribbon The ceremony, known as 'Tijerales' in Chile, is the equivalent to the 'roof-topping ceremony' that takes place worldwide, in one form or another, to celebrate reaching the highest level of a construction. It this case, the construction is the unique ALMA Operations Support Facility (OSF), located near the town of San Pedro de Atacama. "The end of this first stage represents an historic moment for ALMA," said Hans Rykaczewski, the European ALMA Project Manager. "Once completed in December 2007, this monumental building of 7,000 square metres will be one of the largest and most important astronomical operation centres in the world." ALMA, located at an elevation of 5,000m in the Atacama Desert of northern Chile, will provide astronomers with the world's most advanced tool for exploring the Universe at millimetre and submillimetre wavelengths. ALMA will detect fainter objects and be able to produce much higher-quality images at these wavelengths than any previous telescope system. The OSF buildings are designed to suit the requirements of this exceptional observatory in a remote, desert location. The facility, which will host about 100 people during operations, consists of three main buildings: the technical building, hosting the control centre of the observatory, the antenna assembly building, including four antenna foundations for testing and maintenance purposes, and the warehouse building, including mechanical workshops. Further secondary buildings are the transporter shelters and the vehicle maintenance facilities as well as the ALMA gate house. The construction started in August 2006 and will be completed in December 2007. ESO PR Photo 13b/07 ESO PR Photo 13b/07 The Ceremony The ceremony took place in the presence of representatives of the regional authorities, members of the Chilean Parliament, and representatives of the local community, including the mayor of San Pedro, Ms. Sandra Berna, who joined more than 40 representatives of ESO, NRAO and NAOJ - the organisations that are, together, building ALMA. "This is certainly a big step in the realisation of the ALMA Project. The completion of this facility will be essential for assembly, testing and adjustment as well as operation and maintenance of all ALMA antennas from Europe, North America and from Japan," said Ryusuke Ogasawara, the representative of NAOJ in Chile. "This is a tremendous achievement and represents a major milestone for the ALMA project," said Adrian Russell, North American Project Manager for ALMA. ESO PR Photo 13c/07 ESO PR Photo 13c/07 The OSF (Artist's View) The first ALMA antennas, the prototypes of which successfully achieved their first combined astronomical observation last week, are expected to arrive at the ALMA site in a few months. These huge antennas will travel in pieces from Europe, USA and Japan and will be assembled next to the OSF building. The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership among Europe, Japan and North America, in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organisation for Astronomical Research in the Southern Hemisphere, in Japan by the National Institutes of Natural Sciences (NINS) in cooperation with the Academia Sinica in Taiwan and in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC). ALMA construction and operations are led on behalf of Europe by ESO, on behalf of Japan by the National As
Density dependence of reactor performance with thermal confinement scalings
Energy confinement scalings for the thermal component of the plasma published thus far have a different dependence on plasma density and input power than do scalings for the total plasma energy. With such thermal scalings, reactor performance (measured by Q, the ratio of the fusion power to the sum of the ohmic and auxiliary input powers) worsens with increasing density. This dependence is the opposite of that found using scalings based on the total plasma energy, indicating that reactor operation concepts may need to be altered if this density dependence is confirmed in future research.
Stotler, D.P.
Design and performance of Skylab thermal/environmental control system
The function of the thermal/environmental control systems was to provide a comfortable thermal environment for the crew, to cool electronic components, to supply a controlled oxygen/nitrogen atmosphere, and to remove moisture, carbon dioxide, odors, and trace contaminants from the atmosphere. A separate refrigeration system was used to chill and freeze food and biomedical samples and to provide cold water for drinking. This paper describes system design and compares in-flight performance to preflight predictions. A discussion of in-flight anomalies and corrective actions is also included.
Hopson, G. D.; Littles, J. W.; Patterson, W. C.
Classification of basic roof types based on VHR optical data and digital elevation model
In the frame of seismic vulnerability assessment in urban areas, it is very important to estimate the nature of the roof of every building and, in particular, to make the difference between flat roofs and gable ones. In order to perform this tedious task automatically on a large scale, remote sensing data provide a useful solution. In this study, we
Silvia Valero; Jocelyn Chanussot; Philippe Gueguen
Nanostructure model of thermal conductivity for high thermoelectric performance
The effective medium theory of thermal conductivity of two-phase composites studied by Nan et al. has been extended to investigate concentrated nanocomposites. Due to the presence of inter-particle phonon scattering processes in concentrated nanocomposites, the effective lattice thermal conductivity keff varies more rapidly with the volume fraction of second-phase inclusions in the composite. Applying the new keff expressions to monolithic material systems, the results are found to capture the experimental trend of monolithic nanostructured materials. In particular, it is noted that the dimensionless figure of merit, ZT, is nearly doubled by only reducing the lattice thermal conductivity. Two-phase nanocomposites have also been evaluated, demonstrating that these latter systems are very suited for high thermoelectric performance. Present study leads to several strategies for obtaining ZT ~ 2 or higher in nanocomposites.
Poon, S. J.; Limtragool, K.
Thermal management and overall performance of a high concentration PV
An advanced thermal management approach for HCPV systems is demonstrated in this manuscript, proposing the concept of efficient heat recovery at ultra high concentration ratios by collecting the heat on a high temperature level. With the availability of this low grade heat, the efficiency of the HCPV system is increased further as the 'waste' heat is supplied to different thermal consumers engaging in thermal desalination or adsorption cooling processes. To asses the value of the concept, we have estimated the economic value of heat with regard to its consumer and observed that this differs from its thermodynamic value. This valuable input is was used to determine the overall generated value of a dual output system as a function of the operation temperature, where we have actively demonstrated a superior performance of the HCPVT.
Escher, Werner; Paredes, Stephan; Zimmermann, Severin; Ong, Chin Lee; Ruch, Patrick; Michel, Bruno
Validation of a simulation model for water desalination in a greenhouse roof through laboratory experiments and conceptual parameter discussions
Water desalination in a greenhouse roof means that solar energy is absorbed for evaporation from a thin, flowing layer of water. Earlier a quite detailed simulation model was developed for analysis of the thermal and optical characteristics of this desalination system concept. This paper describes laboratory experiments with a small roof module and presents measurements compared to simulations obtained in
M. T. Chaibi
Thermal performance of various multilayer insulation systems below 80K
The SSC collider dipole cryostat consists of a vacuum shell operating at room temperature, two thermal shields operating near 80K and 20K respectively, and the superconducting magnet assembly operating near 4K. The cryostat design incorporates multilayer insulation (MLI) blankets to limit radiant heat transfer into the 80K and 20K thermal shields. Also, an MLI blanket is used to impede heat transfer through residual gas conduction into the 4K superconducting magnet assembly. A measurement facility at Fermilab has been used to experimentally optimize the thermal insulation system for the dipole cryostat. Previous thermal measurements have been used to define the 80K MLI system configuration and verify system performance. With the 80K MLI system defined, the current effort has focused on experimentally defining the optimum insulation scheme for the 20K thermal shield. The SSC design specification requires that radiant heat transfer be limited to 0.093 W/m{sup 2} at an insulating vacuum of 10{sup {minus}6}torr.
Boroski, W.N.; Nicol, T.H.; Schoo, C.J.
The SSC collider dipole cryostat consists of a vacuum shell operating at room temperature, two thermal shields operating near 80K and 20K respectively, and the superconducting magnet assembly operating near 4K. The cryostat design incorporates multilayer insulation (MLI) blankets to limit radiant heat transfer into the 80K and 20K thermal shields. Also, an MLI blanket is used to impede heat transfer through residual gas conduction into the 4K superconducting magnet assembly. A measurement facility at Fermilab has been used to experimentally optimize the thermal insulation system for the dipole cryostat. Previous thermal measurements have been used to define the 80K MLI system configuration and verify system performance. With the 80K MLI system defined, the current effort has focused on experimentally defining the optimum insulation scheme for the 20K thermal shield. The SSC design specification requires that radiant heat transfer be limited to 0.093 W/m[sup 2] at an insulating vacuum of 10[sup [minus]6]torr.
Thermal Performance Experiment for Sintered Aluminum Fibrous Heat Sink
This paper is concerned with the thermal performances and frictional characteristics for sintered aluminum fibrous heat sink. The results obtained experimentally include the effect of fiber diameter, porosity and air flow velocity on the thermal performance. The experimental results were compared with the previous studies such as results for an aluminum foam heat sink and results for a copper fibrous layer. The relations between Nusselt number (NuD) and pumping power characteristics (Cfp�ReD3) were very sensitive to fiber diameter (dw) and these are expressed in following equations, NuD=28.26(Cfp �ReD3 �10-10)0.188 in the case of dw=0.14 mm,NuD=46.35(Cfp�ReD3�10-10)0.139 in the case of dw=0.54 mm, respectively.
Komatsu, Yoshimi; Sugawara, Masahiro; Sato, Kansai; Fujita, Tadashi
Single Port Electro-Thermal Propulsion-Performance Factors
Performance models for single port ETP (Electro-Thermal Propulsion) devices are presented considering all significant efficiency factors. Single-port ETP devices, which use the nozzle exit as entrance port for beamed power, are capable of high efficiency and high thrust with low mass penalty for both propellant and structure. Previously considered parabolic nozzle shapes have operated in pulse mode to exchange energy at a concentrated focal region, resulting in low efficiency. The proposed cone/bell shape diffuses the focal region prior to chamber entry to allow continuous combustion inside the chamber with high efficiency. Mechanical and thermal limits are evaluated. For vacuum operation, low chamber pressure operation is possible. Thin wall thruster construction results in low chamber and nozzle mass. Further, at low pressure, regenerative cooling is needed only for the chamber and throat region with radiation cooling for the nozzle exit region. These factors permit high expansion ratio and thrust-to-weight ratio needed for performance.
Johansen, Donald G.
The effect of DEB powder processing on thermal cell performance
During the last twenty years, the system Ca/LiCl-KCl-CaCrO4/Fe has provided the basis for thermal batteries designed for military applications. In connection with greater performance demands, investigations are being conducted concerning the effect of catholyte processing on thermal cell performance. The catholyte layer is composed of three components including the depolarizer (D), CaCrO4, the electrolyte (E), LiCl-KCl eutectic, and the binder (B), finely divided SiO2. The catholyte layer or DEB pellets are produced by blending these components, fusing, pulverizing the cake, and hydrostatically pressing the powder into pellets. A description is given of ten powders which were prepared for the reported study. It was found that the procedure used in powder processing affects the capacity, but not its voltage. Increasing the prebake temperature for CaCrO4 from 400 to 600 C resulted in an increase in capacity.
Szwarc, R.; Walton, R. D.
Performance of thermally-chargeable supercapacitors in different solvents.
The influence of solvent on the temperature sensitivity of the electrode potential of thermally-chargeable supercapacitors (TCSs) is investigated. For large electrodes, the output voltage is positively correlated with the dielectric constant of solvent. When nanoporous carbon electrodes are used, different characteristics of system performance are observed, suggesting that possible size effects must be taken into consideration when the solvent molecules and solvated ions are confined in a nanoenvironment. PMID:24831049
Lim, Hyuck; Zhao, Cang; Qiao, Yu
Thermal performance of a geofluid direct-contact heat exchanger
A sieve-tray direct-contact heat exchanger was used to transfer heat from a 280°F geothermal fluid to the working fluid, isobutane, in the Raft River 60kW prototype plant. A series of experiments were run at different working fluid-to-geofluid flow ratios which produced different boiling conditions. In this paper, the results of these experiments are analyzed on the basis of thermal performance.
D. J. Wiggins; G. L. Mines; E. Wahl
Thermal performance of multilayer insulation applied to small cryogenic tankage
A study was carried out, providing good design data for multilayer insulation for the range of boundary temperatures and cryogenic tank size utilized. The silk net\\/double-aluminized Mylar system, wrapped one layer at a time, shows a relatively small degradation when applied to tankage, compared to the thermal performance of a flat-plate sample. The Tissuglas\\/double-aluminized Mylar system showed a large installation
G. A. Bell; T. C. Nast; R. K. Wedel
Mastin double-envelope house: a thermal performance evaluation
An evaluation is made of the thermal performance of a double-envelope house of Ekose'a design built by Robert Mastin in Middletown, Rhode Island. The home has two shells with an air space between through which air can circulated. Monitoring of the house in the heating season showed that the requirements for auxiliary heat are very low, about 2.1 Btu per
R. F. Jones; G. Dennehy
Thermal performance evaluation of the infrared telescope dewar subsystem
Thermal performance evaluations (TPE) were conducted with the superfluid helium dewar of the Infrared Telescope (IRT) experiment from November 1981 to August 1982. Test included measuring key operating parameters, simulating operations with an attached instrument cryostat and validating servicing, operating and safety procedures. Test activities and results are summarized. All objectives are satisfied except for those involving transfer of low pressure liquid helium (LHe) from a supply dewar into the dewar subsystem.
Urban, E. W.
Applications for high-performance thermal imaging cameras
High-performance thermal imaging cameras based on indium antimonide (InSb) focal plane arrays (FPAs) offer excellent sensitivity in the midwave infrared band, notably in the 3-5 micron waveband. Noise levels below 20 mK enable detection of surface temperature differences of 0.1 C, and the high-speed response of the InSb photodetectors enablesv the capture of events on time scale as short as
Austin A. Richards
Life sciences passive GN2 freezer thermal performance test
Thermal performance tests that were conducted on the life sciences passive GN2 freezer project are summarized as well as the improvements to the freezers to improve the thermal performance of the containers. Procedures were developed, based upon these tests, to initially charge the freezers with LN2 and verify that the freezer performance is adequate for the mission duration. Improvements were made to the corvac sample tube to limit the amount of breakage due to thermal expansion of the liquid during freezing. A method of verifying the freezer vacuum insulative integrity was defined as well as a procedure for refurbishment of the internal vacuum level. Freezer modifications were made to ease the reevacuation of the containers. The orientation of the freezer in a 1-G environment, after being charged, had to remain in a vertical position. The LN2 boiloff rate increased significantly in a horizontal position. This resulted in a stowage definition in the spacecraft prior to launch. Functional testing, using the SL-1 mission timeline showed that the freezer will maintain samples in the frozen state for the duration of the mission.
Belshaw, G. W.
Heat exchanger thermal performance for two nonazeotropic refrigerant mixtures
Two nonazeotropic refrigerant mixtures (NARMs), the first consisting of 71 percent R22 and 29 percent R114 and the second consisting of 75 percent R143a and 25 percent R124 (approximate percentages by mass), were studied at various mass flow rates and heat loads in an experimental apparatus at Oak Ridge National Laboratory. The measured thermal performance of the evaporator and the condenser are presented in terms of the number of transfer units (NTU) and effectiveness epsilon. Because the phase-change process of the NARMs is nonisothermal, a specific heat for the two-phase region can be defined. This two-phase specific heat for the NARMs varies with respect to enthalpy. Because the standard NTU-(epsilon) analysis is valid only for constant specific heat fluids, an analysis that considers variable specific heat fluids is used to compare analytical predictions of the thermal performance with the observed thermal performance. The predicted and measured results show very good agreement when the pressure drop is low.
Conklin, J. C.; Vineyard, E. A.
Roof Polishing of Optical Fibers
Bevealed tip gives optimum coupling efficiency. Abrasive tape used to grind tip of optical fiber. Grinding force depends on stiffness of optical fiber. "Roof" shape on end of optical glass fiber increases efficiency which couples laser light. End surface angle of 65 degrees with perpendicular required for optimum coupling. Since fiber and tape are light in weight and compliant, ridge defect-free, and chipping on fiber edge totally eliminated.
Dholakia, A. R.
Analysis of thermal performance of penetrated multi-layer insulation
Results of research performed for the purpose of studying the sensitivity of multi-layer insulation blanket performance caused by penetrations through the blanket are presented. The work described in this paper presents the experimental data obtained from thermal vacuum tests of various penetration geometries similar to those present on the Hubble Space Telescope. The data obtained from these tests is presented in terms of electrical power required sensitivity factors referenced to a multi-layer blanket without a penetration. The results of these experiments indicate that a significant increase in electrical power is required to overcome the radiation heat losses in the vicinity of the penetrations.
Foster, Winfred A., Jr.; Jenkins, Rhonald M.; Yoo, Chai H.; Barrett, William E.
Green Roof Research through EPA's Regional Applied Research Effort - slides
The U.S. Environmental Protection Agency?s (EPA) Regional Applied Research Effort (RARE) allows the Regions of the EPA to choose research projects to be performed in partnership with EPA?s Office of Research and Development (ORD). Over the last decade, several green roof projects...
The effect of thermal loading on laboratory fume hood performance.
A modified version of the ANSI/ASHRAE 110-1995 Method of Testing Performance of Laboratory Fume Hoods was used to evaluate the relationship between thermal loading in a laboratory fume hood and subsequent tracer gas leakage. Three types of laboratory burners were used, alone and in combination, to thermally challenge the hood. Heat output from burners was measured in BTU/hr, which was based on the fuel heat capacity and flow rate. Hood leakage was measured between 2824 and 69,342 BTU/hr. Sulfur hexafluoride (SF6) was released at 23.5 LPM for each level of thermal loading. Duct temperature was also measured during the heating process. Results indicate a linear relationship for both BTU/hr vs. hood leakage and duct temperature vs. hood leakage. Under these test conditions, each increase of 10,000 BTU/hr resulted in an additional 4 ppm SF6 in the manikin's breathing zone (r2 = 0.68). An additional 3.1 ppm SF6 was measured for every 25 degrees F increase in duct temperature (r2 = 0.60). Both BTU/hr and duct temperature models showed p < 0.001. For these tests, BTU/hr was a better predictor of hood leakage than duct temperature. The results of this study indicate that heat output may compromise fume hood performance. This finding is consistent with those of previous studies. PMID:11062932
Johnston, J D; Chessin, S J; Chesnovar, B W; Lillquist, D R
Optical performance of bimetallic mirrors in thermal environments
Evaluation of the optical performances of bimetallic mirrors with various substrate shapes was conducted using the finite element analysis program, SDRC-IDEAS. In these analyses, two different plating materials, nickel and aluminum were considered for an aluminum and a beryllium mirror substrate. Thermal environments used in this study are: a unit thermal soak (temperature difference), an axial temperature distribution, and radial temperature distributions on the mirror substrate. The goal of this study is to optimize the optical surface quality for various plating thicknessess. Surface errors, individual aberration terms, such as piston, tilts, focus and other aberrations were obtained by the program PCFRINGE. It was found that the optical performances of bimetallic mirrors depend on the plating material, plating thickness, and the mirror substrate materials. The optimum plating thickness combinations were determined based on plating material and mirror substrate with variation of temperature distributions. The results were compared with the optical surface errors and the corrected surface errors. The results indicate that there does not exist a definite common rule for the optimum, but a detailed analysis such as presented herein is generally needed to design bimetallic mirrors in a thermal environment.
Moon, Il Kweon
Indoor thermal performance evaluation of Daystar solar collector
The test procedures used and results obtained from a test program to obtain thermal performance data on a Daystar Model 21B, S/N 02210, Unit 2, liquid solar collector under simulated conditions are described. The test article is a flat plate solar collector using liquid as a heat transfer medium. The absorber plate is copper and coated with black paint. Between the tempered low iron glass and absorber plate is a polycarbonate trap used to suppress convective heat loss. The collector incorporates a convector heat dump panel to limit temperature excursions during stagnation. The following tests were conducted: (1) collector thermal efficiency; (2) collector time constant; (3) collector incident angle modifier; (4) collector heat loss coefficient; and (5) collector stagnation.
Shih, K., Sr.
The Development of Composites with Negative Thermal Expansion Properties Using High Performance Fibers
Almost all solid materials exhibit positive thermal expansivity. However, in many engineering designs, materials with negative thermal expansivity are desirable. The characteristics of high performance fibers, such as high strength, exceptional thermal conductivity and electrical insulation may also include negative thermal expansivity. Therefore, it should be possible to develop fiber reinforced composites with negative thermal expansivity by using an optimum
Yang Hua; Qing-Qing Ni; Atsuhiko Yamanaka; Yoshihiko Teramoto; Toshiaki Natsuki
High-performance IR thermography system based on Class II Thermal Imaging Common Modules
The Class II Thermal Imaging Common Modules were originally developed for the U.K. Ministry of Defence as the basis of a number of high performance thermal imaging systems for use by the British Armed Forces. These systems are characterized by high spatial resolution, high thermal resolution and real time thermal image update rate. A TICM II thermal imaging system uses
Ian G. Bell
Condensing economizers: Thermal performance and particulate removal efficiencies
Condensing economizers can be used to increase the thermal efficiency of boilers and furnaces. This project has involved a study of these specifically for application to coal-water mixture fuels although the results can be extended to other fuels. experimental studies to evaluate thermal performance and removal of particulates across indirect contract economizers have been performed. The test arrangement incorporates oil firing with the injection of flyash into the flue gas to simulate coal combustion products. Water sprays into the combustion products are used to achieve variable flue gas moisture content and a variable amount of condensation in the economizers. The economizers are tubular with flue gas on the outside of the tubes. Tube surfaces are plastic coated to prevent corrosion. The gas temperature and condensation profiles through the economizers have been predicted and overall predicted performance has been compared with test results. Mechanisms for particle removal are discussed and predicted removal efficiencies as a functions of particle diameter are presented. It is is shown that inertial impaction is the dominant mechanism and particle removal efficiencies up to 89% have been realized.
Butcher, T.A.; Litzke, Wai Lin (Brookhaven National Lab., Upton, NY (United States)); Park, N. (Stony Brook Scientific, Ltd., Morristown, PA (United States))
Thermal Performance Study of a Prototype Multiport Heat Exchanger
Great efforts have been made to investigate the thermal performance and fluid flow behaviour in Minichannel Heat Exchangers (MICHX), however, the examination of air side in a multiport serpentine slab heat exchanger is rare. In the current investigation, experiments were conducted on air heating via a prototype multiport MICHX. Hot DI-water at different mass flow rates and a constant inlet temperature of 70�C was passed through the channels. The water side Reynolds numbers were varied from 255 to 411. The airside Reynolds numbers were calculated based on the free mean stream velocity and varied from 1750 to 5250, while, the air inlet temperatures were in the range of 22.5�C to 34.5�C. The effects of dimensional parameters, such as Reynolds number, Nusselt number, Prandtl number, Brinkman number, and Dean number on the heat transfer performance were investigated. The effect of the serpentine on the enhancement of DI water thermal performance behaviour was studied. Heat transfer correlations were established and compared to the results in the open literature.
Fotowat, Shahram
Thermal performance analysis of vacuum variable-temperature blackbody system
In this paper, the design and structure of a vacuum variable-temperature blackbody system were described, and the steady-state thermal analysis of a 3-D blackbody model was presented. Also, the thermal performance of the blackbody was evaluated using an infrared camera system. The blackbody system was constructed to operate under vacuum conditions (2.67 � 10?2 Pa) to reduce its temperature uncertainty, which can be caused by vapor condensation at low temperatures usually below 273.15 K. A heat sink and heat shield including a cold shield were embedded around the radiator to maintain the heat balance of the blackbody. A simplified 3-D model of the blackbody including a radiator, heat sink, heat shield, cold shield, and heat source was thermophysically evaluated by performing finite elements analysis using the extended Stefan�Boltzmann's rule, and the infrared radiating performance of the developed system was analyzed using an infrared camera system. On the basis of the results of measurements and simulations, we expect that the suggested blackbody system can serve as a highly stable reference source for the calibration and measurement of infrared optical systems within operational temperature ranges.
Lee, Sang-Yong; Kim, Geon-Hee; Lee, Young-Shin; Kim, Ghiseok
Effects of mechanical and thermal fatigue on dental drill performance.
Osseous integration of dental implants depends on the use of proper surgical technique during site preparation, including the prevention of thermal injury to the surrounding bone. Heat generation during drilling has been reported to positively correlate with the production of forces at the surgical site. In this study, peak torque and axial load levels were measured during a drilling procedure into a polymeric material simulating the human mandible. Axial rotary milling was performed using 5 different twist drill designs (3i Irrigated Tri-Spade, 3i Disposable, Nobel-Biocare, Straumann, and Lifecore) of 15 to 20 mm in length and 2 to 2.3 mm in diameter, at a free-running rotational speed of 1,500 rpm and continuous feed rate of 3.5 mm/second, to a total depth of 10.5 mm. Ten drills representing each of the 5 types (n = 50) were subjected to 30 individual drill "pecks" and heat-sterilized every 3 "pecks" to determine the effects of cyclic mechanical and thermal loading on drill performance. Normal stress (sigma) and shear stress (tau) were calculated from the kinetic data and drill geometries. A drill efficiency coefficient (mu) was also calculated as the ratio of torsional resistance to translational resistance. Overall, the hypotheses of drill performance dependency on drill type as well as mechanical and thermal accumulated loading were tested and confirmed (P < .05). The 5 drill types produced a range of normal stresses (2.54 to 5.00 MPa), shear stresses (9.69 to 29.71 MPa), and efficiency (1.16 to 3.16) during repeated testing. Scanning electron microscopic images revealed minor deformations in the cutting edges of the tri-spade drills following testing. PMID:11769832
Harris, B H; Kohles, S S
Thermal expansion pump for capillary high-performance liquid chromatography.
A thermal expansion pump (TEP) based on a principle of liquid thermal expansion for capillary high-performance liquid chromatography has been developed. The novel pump is capable of generating a continuous flow at high pressure for constant and stable delivery of binary solvents from nanoliters to microliters per minute without splitting. Theoretical equations for controlling fluidic output of this pump have been established and validated by a series of experiments. Factors affecting flow rate, such as density discrepancy, liquid compressibility, and mass loss in output, were taken into account. An assembly of the pump system employing two groups of thermal expansion pumps (TEPs) working in turns were fabricated, and a controlling strategy for the pump system to maintain a continuous delivery without pressure fluctuation even at switching points was also developed. Both isocratic and gradients of binary solvent delivery by the TEPs were performed. Reproducibility and standard deviation at different flow rates were determined. A capillary high-performance liquid chromatography (micro-HPLC) system consisting of the TEPs, an injection valve, a homemade packed capillary column (20 cm x 100 microm i.d. with 5 microm C18), and a laser-induced fluorescence detector was set up, and sample separations were carried out. Results of RSD = 4% for flow and RSD = 2% for retention times at 500 nL/min were achieved. Such a pump system has almost no moving parts except for the solvent switches. Its overall costs of manufacture and running are very low. It is proven that the TEPs system has great potential and competitive capabilities in capillary liquid chromatography. PMID:20050677
Tao, Qian; Wu, Qian; Zhang, Xiangmin
Thermal performance of honeywell double covered liquid solar collector
The test procedures and results obtained during an evaluation test program to determine the outdoor performance characteristics of the Honeywell liquid solar collector are presented. The program was based on the thermal evaluation of a Honeywell double covered liquid solar collection. Initial plans included the simultaneous testing of a single covered Honeywell collector. During the initial testing, the single covered collector failed due to leakage; thus, testing continued on the double covered collector only. To better define the operating characteristics of the collector, several additional data points were obtained beyond those requested.
Losey, R.
Thermal performance evaluation of the Semco (liquid) solar collector
Procedures used and results obtained during the evaluation test program on a flat plate collector which uses water as the working fluid are discussed. The absorber plate is copper tube soldered to copper fin coated with flat black paint. The glazing consists of two plates of Lo-Iron glass; the insulation is polyurethane foam. The collector weight is 242.5 pounds with overall external dimensions of approximately 48.8 in. x 120.8 in. x 4.1 in. The test program was conducted to obtain thermal performance data before and after 34 days of weather exposure test.
Thermal performance of advanced heat exchangers for ammonia refrigeration systems
Current practice in the ammonia industry is to use plain tubes. This article demonstrates that the coefficient of performance (COP) can be increased by about 11% using tubes with ammonia-side enhancement and by about 26% using tubes with ammonia-side and water-side enhancement. Further improvements with respect to energy and cost are possible with the compact heat exchanger types -- plate-frame and plate-fin -- because they can be optimized for the system conditions for each application. These findings are based on experimentally determined overall heat transfer coefficients that were obtained for candidate heat exchangers for the Ocean Thermal Energy Conversion (OTEC) program.
Panchal, C.B.; Rabas, T.J. [Argonne National Lab., IL (United States)
Thermal performance and design of a solid particle cavity receiver
A model for energy transport in a solid particle cavity receiver is developed and applied to the design and analysis of a receiver for the Central Receiver Test Facility (CRTF), Albuquerque, New Mexico. The model gives thermal performance results including; particle temperatures, cavity efficiencies, and wall temperatures, which directly affect the economic and technical feasibility of a solid particle receiver. In addition, design criteria relevant to the configuration of a solid particle cavity receiver are developed. Results for CRTF indicate that at design conditions particle temperatures will exceed 1200 K with cavity efficiencies on the order of 75%.
Lajeunesse, C. A.
Performance verification tests of an integrated heat pipe-thermal energy storage system have been conducted. This system is being developed as a part of an Organic Rankine Cycle-Solar Dynamic Power System (ORC-SDPS) receiver for future space stations. The integrated system consists of potassium heat pipe elements that incorporate thermal energy storage (TES) canisters within the vapor space along with an organic fluid (toluene) heater tube used as the condenser region of the heat pipe. During the insolation period of the earth orbit, solar energy is delivered to the surface of the heat pipe elements of the ORC-SDPS receiver and is internally transferred by the potassium vapor for use and storage. Part of the thermal energy is delivered to the heater tube and the balance is stored in the TES units. During the eclipse period of the orbit, the stored energy in the TES units is transferred by the potassium vapor to the toluene heater tube. A developmental heat pipe element was fabricated that employs axial arteries and a distribution wick connecting the wicked TES units and the heater to the solar insolation surface of the heat pipe. Tests were conducted to verify the heat pipe operation and to evaluate the heat pipe/TES units/heater tube operation by interfacing the heater unit to a heat exchanger.
Keddy, E.; Sena, J.T.; Merrigan, M.
Thermal dependence of sprint performance of the lizard Sceloporus occidentalis.
Sprint velocity of the lizard Sceloporus occidentalis was maximal at preferred body temperature (Tb, 35 degrees C). Mean running velocity (VR) and stride frequency (f) at this temperature were 3.23 +/- 0.7 (mean +/- S.E.M.) ms-1 and 15.6 +/- 0.3 s-1, respectively. VR and f did not change significantly when Tb was raised to 40 degrees C. At Tb values between 25 and 35 degrees C the thermal dependencies of VR (Q10 = 1.23) and f (Q10 = 1.12) were quite low. At Tb values below 25 degrees C the thermal dependence of these factors increased markedly. Stride length (LS) was independent of Tb from 15 to 40 degrees C. Lizards with a Tb of 10 degrees C were largely incapacitated, and VR, f and LS were all greatly reduced. Comparisons with measurements of the contractile properties of skeletal muscle of this species suggest that stride frequency is limited by the twitch contraction time at temperatures below 23 degrees C. At higher temperatures, sprint performance is nearly independent of the thermal effects on the muscles. PMID:3806004
Marsh, R L; Bennett, A F
Improving the thermal performance of the US residential window stock
Windows have typically been the least efficient thermal component in the residential envelope, but technology advances over the past decade have helped to dramatically improve the energy efficiency of window products. While the thermal performance of these advanced technology windows can be easily characterized for a particular building application, few precise estimates exist of their aggregate impact on national or regional energy use. Policy-makers, utilities, researchers and the fenestration industry must better understand these products` ultimate conservation potential in order to determine the value of developing new products and initiating programs to accelerate their market acceptance. This paper presents a method to estimate the conservation potential of advanced window technologies, combining elements of two well-known modeling paradigms: supply curves of conserved energy and residential end-use forecasting. The unique features include: detailed descriptions of the housing stock by region and vintage, state-of-the-art thermal descriptions of window technologies, and incorporation of market effects to calculate achievable conservation potential and timing. We demonstrate the methodology by comparing, for all new houses built between 1990 and 2010, the conservation potential of very efficient, high R-value ``superwindows`` in the North Central federal region and spectrally-selective low-emissivity (moderate Revalue and solar transmittance) windows in California.
Brown, R.E.; Arasteh, D.K.; Eto, J.H.
Graphite first wall thermal performance in ICF reactor
Graphite has been considered as a candidate material for the first wall in ICF reactors. This paper shows the thermal performance of the graphite first wall (GFW) in the 0.25 ?m laser driven materials test reactor SIRIUS-M. The first wall temperature response due to the X-rays, reflected laser light, and ions that emanate from the 13.4 MJ yield target was calculated for dry GFWs which were either unprotected or gas protected. Evaporation rates and thermal stresses were calculated and minimum radii were chosen for both cases. It was found that the reflected laser light from the target produces the highest temperature rise in the gas protected GFW. If 10% of the laser light is reflected from the target and the reflectivity of graphite is 50%, the maximum thermal stress in the GFW is about 90% of the compressive strength for a 2 m radius cavity. Therefore, the viability of the first wall design depends critically on the laser light reflected from the target. the graphite reflectivity and the strength of the graphite.
Attaya, H.; Lovell, E.; Engelstad, R.; Peterson, R.; Liang, J.; Abdel-Khalik, S.; Moses, G.; Kulcinski, G.
Evaluation of Thermal Performance of Flame-resistant Fabrics Considering Thermal Wave Influence in Human Skin Model
A thermal wave skin model incorporating surface heat flux from a skin simulant sensor is developed to characterize the thermal performance of flame-resistant (FR) fabrics covering the skin simulant sensor. Comparison of the results of time to 2nd degree skin burn and temperature elevation of skin beneath a layer of fabric obtained from the newly developed thermal wave skin model
Fang-Long Zhu; Wei-Yuan Zhang
40 CFR 65.45 - External floating roof converted into an internal floating roof.
...2013-07-01 2013-07-01 false External floating roof converted into an internal floating roof. 65.45 Section 65.45 Protection...RULE Storage Vessels § 65.45 External floating roof converted into an internal floating...
Development of a Small High Performance Thermal Infrared Detection Aid.
This Memorandum describes the proposed development of a small, lightweight thermal IR detection aid, capable of operation as an IR intrusion sensor, a thermal pointer and a man-portable thermal imager.
K. C. Liddiard
Miniaturized high-performance starring thermal imaging system
A high resolution thermal imaging system was developed based on a 384 X 288 mercury cadmium telluride (MCT) mid wave (MWIR) infrared (IR) detection module with a 2 X 2 microscan for improved geometrical resolution. Primary design goal was a long identification range of 3 km and high system performance for adverse weather conditions achieved by a system with small entrance pupil and minimized dimensions to fit for integration in existing apertures of armored vehicles, reconnaissance systems and stabilized platforms. A staring FPA module with its potential for long integration times together with a microscan for improved geometrical resolution provides the answers best fit to these requirements. A robust microscanner was developed to fit for military requirements and integrated with AIM's 384 X 288 MCT MWIR module and data processing. The modules allow for up to 2 ms integration time with 25 Hz frame rate and output a 768 X 576 high resolution CCIR standard image. The video image processing (VIP) provides the calculation power for scene based self learning nonuniformity correction (NUC) algorithms to save calibration sources. This NUC algorithm allows take into account non linear effects for unsurpassed performance in highly dynamic scenes. The detection module and VIP are designed to interface with STN's mature system electronics, used e.g. in hundreds of OPHELIOS thermal camera sets fielded. The system electronics provides a lot of different interface features like double serial control bus (CANBUS) interface, analog and digital outputs as well as different video outputs. The integrated graphic generation part allows to put advanced graphic overlays to the thermal image and also to external video signals via the video input feature. This electronics provides the power supply for the whole thermal imaging system as well as different processor controlled algorithms for field of view or zoom drives, focus drives, athermalization and temperature control of the FLIR. A new zoom lens F/2.0 allows to select field of views from 2 degree to 15 degrees horizontal. This covers a wide area of military and paramilitary applications. The whole camera is miniaturized to fit into existing gunner and commander sights for main battle tanks as well as for infantry fighting vehicles. The overall design is compatible in optical, electrical and mechanical direction with the fielded OPHELIOS cameras and so an easy upgrade for existing fire control, reconnaissance and platform systems. The overall design is made under consideration of mil standard environments and is able to withstand vehicle, airborne and shipborne stress. The presentation gives an overview of the different components of the new camera system. Theoretical range performance data are discussed together with measured NETD, MTF and MRTD data of the unit.
Cabanski, Wolfgang A.; Breiter, Rainer; Mauk, Karl-Heinz; Rode, Werner; Ziegler, Johann; Ennenga, L.; Lipinski, Ulrich M.; Wehrhahn, T.
Improving the performance of lysimeters with thermal imaging
Precision weighing lysimeters generate data of evapotranspiration (ET) at a high resolution in the order of 0.01 to 0.05 mm. Though this resolution is often reported as the accuracy of the lysimeter, it is in fact the precision of the weighing device. The accuracy of a lysimeter is heavily dependent on its ability to duplicate environmental conditions of its surroundings. In general, measurement errors will decrease with increasing lysimeter dimension, primarily because a larger part of the lysimeter is unaffected by its boundaries and because heterogeneities in soil hydraulic properties and micro-climate are more averaged out. However, the cost of large lysimeters make them unattractive and scientists often choose for more economical solutions, optimizing between lysimeter dimensions and costs. Instead of investing in large lysimeters or putting effort in duplicating environmental conditions, we invested in monitoring the surface temperature of zero tension lysimeters with a thermal infrared camera to detect deviations in ET. In such a system, measurement errors caused by deviations in moisture content can be compensated, without the struggle of controlling the lysimeter moisture content with pressure plates and vacuum pumps or preventing wall flow. Other advantages of using thermal imaging are that (i) measurements of ET can be extrapolated to much larger areas than the surface area of most conventional lysimeters, and (ii) ET can be split into soil evaporation and transpiration, which allows us to study the effects of the vegetation structure on the water balance. Several experiments were performed to estimate differences in ET between lysimeters based on the radiometric surface temperature. Two simple methods, 1) linear scaling and 2) a comparison of the surface energy balance were applied to translate differences in surface temperature to differences in ET. We examined the application of both methods on bare sand, moss and grass. We show that the performance of lysimeters can be monitored and improved with the aid of thermal imaging. For example, estimated ET based on thermal images of moss lysimeters showed a model efficiency (Nash Sutcliffe) of 0.94 and 0.93 and a RMSE of 0.02 and 0.03 mm for method 1 and 2 respectively. However, for bare sand the model efficiency was much lower: 0.54 and 0.59 with a RMSE of 0.53 and 0.60 mm for method 1 and 2 respectively. This poor performance is caused by the large variation in albedo of bare sand under moist and dry conditions, affecting the available energy for evaporation.
Voortman, Bernard; Bartholomeus, Ruud; Witte, Jan-Philip
A facility for characterizing the steady-state and dynamic thermal performance of microelectromechanical system thermal switches.
A facility to characterize microelectromechanical system (MEMS) thermal switches by measuring two pertinent figures of merit is described. The two figures of merit measured are the ratio of thermal resistance of the switch in the off and on states, Roff/Ron, and the time required to switch from the off to the on state, tauswitch. The facility consists of two pieces of equipment. A guard-heated calorimeter is used to measure heat transfer across the thermal switch under steady-state conditions. Measuring heat transfer across a thermal switch in both the off and on states then gives the thermal resistance ratio Roff/Ron. A thin-film radial heat-flux sensor is used to measure heat transfer across the thermal switch under dynamic conditions. Measuring heat transfer across a thermal switch as the switch changes from the off to the on state gives the thermal switching time tauswitch. The test facilities enable the control of the applied force on the thermal switch when the thermal switch is on, the thickness of the gas gap when the thermal switch is off, and the gas species and pressure in the thermal switch gas gap. The thermal performance of two MEMS thermal switches employing two different thermal contact materials, a polished silicon surface and an array of liquid-metal microdroplets, is characterized and compared. PMID:18377038
Cho, J H; Richards, C D; Richards, R F
Performance contracting for parabolic trough solar thermal systems
Several applications of solar energy have proven viable in the energy marketplace, due to competitive technology and economic performance. One example is the parabolic trough solar collectors, which use focused solar energy to maximize efficiency and reduce material use in construction. Technical improvements are complemented by new business practices to make parabolic trough solar thermal systems technically and economically viable in an ever widening range of applications. Technical developments in materials and fabrication techniques reduce production cost and expand applications from swimming pool heating and service hot water, to higher-temperature applications such as absorption cooling and process steam. Simultaneously, new financing mechanisms such as a recently awarded US Department of Energy (DOE) Federal Energy Management Program (FEMP) indefinite quantity Energy Savings Performance Contract (Super ESPC) facilitate and streamline implementation of the technology in federal facilities such as prisons and military bases.
Brown, H.; Hewett, R.; Walker, A. [National Renewable Energy Lab., Golden, CO (United States); Gee, R.; May, K. [Industrial Solar Technology, Golden, CO (United States)
The effectiveness of cool and green roofs as urban heat island mitigation strategies
Mitigation of the urban heat island (UHI) effect at the city-scale is investigated using the Weather Research and Forecasting (WRF) model in conjunction with the Princeton Urban Canopy Model (PUCM). Specifically, the cooling impacts of green roof and cool (white/high-albedo) roof strategies over the Baltimore-Washington metropolitan area during a heat wave period (7 June�10 June 2008) are assessed using the optimal set-up of WRF-PUCM described in the companion paper by Li and Bou-Zeid (2014). Results indicate that the surface UHI effect (defined based on the urban�rural surface temperature difference) is reduced significantly more than the near-surface UHI effect (defined based on urban�rural 2 m air temperature difference) when these mitigation strategies are adopted. In addition, as the green and cool roof fractions increase, the surface and near-surface UHIs are reduced almost linearly. Green roofs with relatively abundant soil moisture have comparable effect in reducing the surface and near-surface UHIs to cool roofs with an albedo value of 0.7. Significant indirect effects are also observed for both green and cool roof strategies; mainly, the low-level advection of atmospheric moisture from rural areas into urban terrain is enhanced when the fraction of these roofs increases, thus increasing the humidity in urban areas. The additional benefits or penalties associated with modifications of the main physical determinants of green or cool roof performance are also investigated. For green roofs, when the soil moisture is increased by irrigation, additional cooling effect is obtained, especially when the �unmanaged� soil moisture is low. The effects of changing the albedo of cool roofs are also substantial. These results also underline the capabilities of the WRF-PUCM framework to support detailed analysis and diagnosis of the UHI phenomenon, and of its different mitigation strategies.
Li, Dan; Bou-Zeid, Elie; Oppenheimer, Michael
The pneumatization patterns of the roof of the parapharyngeal space in CBCT
Introduction The rhinopharynx and the parapharyngeal space (PPS) are complex anatomical territories located beneath the skull base. Thorough knowledge of the complex anatomy of the PPS is essential in treatment of pathologies such as parapharyngeal abscesses. The roof of the PPS is overlooked in anatomy. It was hypothesized that the pneumatization pattern of the PPS roof is individually variable, as determined by the variable pneumatization patterns of the sphenoid and temporal bones. The study was aimed at assessing the anatomy of the PPS roof in CBCT. Methods The present study was performed retrospectively on a group of 35 subjects (37.1% males) evaluated by CBCT for various dental procedures. Results The mean age of the group was 37.9 (SD: 14.2, range: 18 to 61). The major bony landmarks of the PPS roof were: the petrous apex with the carotid canal, the jugular foramen, the foramen lacerum, the sphenopetrosal fissure or suture, and the root of the pterygoid process. Variable patterns of pneumatization were determined by the petrous apex air cells and the pterygoalar recess of the sphenoidal sinus. As related to the individually pattern of pneumatization, the following types of the PPS roof were defined: (i) type 1 � not pneumatized PPS roof; (ii) type 2 � sphenoidal but not petrosal pneumatization of the PPS roof; (iii) type 3 � petrosal but not sphenoidal pneumatization of the PPS roof; (iv) type 4 � sphenoidal and petrosal pneumatizations of the PPS roof. Discussion Although on the left side the degree of pneumatization was higher than on the right side, no statistical differences were recorded (p > 0.05). The pattern of pneumatizations in the PPS roof should be assessed when PPS involvement in otitis or sinusitis is considered.
Andrei, Felicia; Motoc, Andrei Gheorghe Marius; Jianu, Adelina Maria; Rusu, Mugurel Constantin; Loreto, Carla
Thermal Insulation Performance Test with an EM Shielding MLI
We have conducted a thermal insulation performance test with an EM (electromagnetic) shielding MLI (multi-layer insulator) and have compared its performances with a conventional MLI thermal insulation. The test was done in a vacuum chamber with a liquid nitrogen temperature shroud. The temperatures at various locations in the MLI were measured to obtain their effective emittances. The EM shielding provides an additional layer of copper fabric as an EM shielding layer, inserted in between conventional MLI layers to enhance EM shielding. The shielding MLI will be used for a lunar radar sounder to protect it from noise emitted by other instruments on board of the spacecraft in the SELENE mission, which is a collaboration mission between ISAS and NASDA. The lunar radar sounder has wide-band and highly sensitive radio wave receivers to detect weak signals in a ``noiseless'' environment on the far side of the moon. The desired signals are extremely weak, especially in the range between 1 MHz and 30 MHz. The EM shielding MLI was also tested and confirmed that its shielding effect was desirable in the specified range.
Iida, T.; Iijima, Y.; Nakazawa, S.
Thermal Performance of a Cryogenic Fluid Management Cubesat Mission
Development for an in-space demonstration of a CubeS at as a Cryogenic Fluid Management (CFM) test bed is currently underway. The favorable economics of CubeSats make them appealing for technology development activity. While their size limits testing to smaller scales, many of the regimes relevant to CFM can still be achieved. The first demo flight of this concept, CryoCube�-1, will focus on oxygen liquefaction and low-gravity level sensing using Reduced Gravity CryoTracker�. An extensive thermal modeling effort has been underway to both demonstrate concept feasibility and drive the prototype design. The satellite will utilize both a sun- and earth-shield to passively cool its experimental tank below 115 K. An on-board gas generator will create high pressure gaseous oxygen, which will be throttled into a bottle in the experimental node and condensed. The resulting liquid will be used to perform various experiments related to level sensing. Modeling efforts have focused on the spacecraft thermal performance and its effects on condensation in the experimental node. Parametric analyses for both optimal and suboptimal conditions have been considered and are presented herein.
Berg, J. J.; Oliveira, J. M.; Congiardo, J. F.; Walls, L. K.; Putman, P. T.; Haberbusch, M. S.
Positive effects of vegetation: urban heat island and green roofs.
This paper attempts to evaluate the positive effects of vegetation with a multi-scale approach: an urban and a building scale. Monitoring the urban heat island in four areas of New York City, we have found an average of 2��C difference of temperatures between the most and the least vegetated areas, ascribable to the substitution of vegetation with man-made building materials. At micro-scale, we have assessed the effect of surface albedo on climate through the use of a climatological model. Then, using the CO(2) equivalents as indicators of the impact on climate, we have compared the surface albedo, and the construction, replacement and use phase of a black, a white and a green roof. By our analyses, we found that both the white and the green roofs are less impactive than the black one; with the thermal resistance, the biological activity of plants and the surface albedo playing a crucial role. PMID:21481997
Susca, T; Gaffin, S R; Dell'osso, G R
40 CFR 1037.140 - Curb weight and roof height.
...2013-07-01 false Curb weight and roof height. 1037.140 Section 1037.140... § 1037.140 Curb weight and roof height. (a) Where applicable, a vehicle's curb weight and roof height are determined from nominal...
Thermal Performance of Orion Active Thermal Control System With Seven-Panel Reduced-Curvature Radiator
The active thermal control system (ATCS) of the crew exploration vehicle (Orion) uses radiator panels with fluid loops as the primary system to reject heat from spacecraft. The Lockheed Martin (LM) baseline Orion ATCS uses eight-panel radiator coated with silver Teflon coating (STC) for International Space Station (ISS) missions, and uses seven-panel radiator coated with AZ 93 white paint for lunar missions. As an option to increase the radiator area with minimal impact on other component locations and interfaces, the reduced-curvature (RC) radiator concept was introduced and investigated here for the thermal perspective. Each RC radiator panel has 15 percent more area than each Lockheed Martin (LM) baseline radiator panel. The objective was to determine if the RC seven-panel radiator concept could be used in the ATCS for both ISS and lunar missions. Three radiator configurations the LM baseline, an RC seven-panel radiator with STC, and an RC seven-panel radiator with AZ 93 coating were considered in the ATCS for ISS missions. Two radiator configurations the LM baseline and an RC seven-panel radiator with AZ 93 coating were considered in the ATCS for lunar missions. A Simulink/MATLAB model of the ATCS was used to compute the ATCS performance. Some major hot phases on the thermal timeline were selected because of concern about the large amount of water sublimated for thermal topping. It was concluded that an ATCS with an RC seven-panel radiator could be used for both ISS and lunar missions, but with two different coatings STC for ISS missions and AZ 93 for lunar missions to provide performance similar to or better than that of the LM baseline ATCS.
Wang, Xiao-Yen J.; Yuko, James R.
Integrated roof wind energy system
Wind is an attractive renewable source of energy. Recent innovations in research and design have reduced to a few alternatives with limited impact on residential construction. Cost effective solutions have been found at larger scale, but storage and delivery of energy to the actual location it is used, remain a critical issue. The Integrated Roof Wind Energy System is designed to overcome the current issues of urban and larger scale renewable energy system. The system is built up by an axial array of skewed shaped funnels that make use of the Venturi Effect to accelerate the wind flow. This inventive use of shape and geometry leads to a converging air capturing inlet to create high wind mass flow and velocity toward a vertical-axis wind turbine in the top of the roof for generation of a relatively high amount of energy. The methods used in this overview of studies include an array of tools from analytical modelling, PIV wind tunnel testing, and CFD simulation studies. The results define the main design parameters for an efficient system, and show the potential for the generation of high amounts of renewable energy with a novel and effective system suited for the built environment.
Suma, A. B.; Ferraro, R. M.; Dano, B.; Moonen, S. P. G.
Wax scraper for floating roof tanks
A wax scraper is described for removing waxy deposits from the inside surface of floating roof storage tanks during the operation of such tanks, without requiring the removal of all obstructions from the inside surface of the tanks. The floating roof structure has affixed to it a number of support means. Each support means carries a scraper blade having scraper
H. A. Maeder; A. H. Nelson; F. R. Neely
Lightweight, self-ballasting photovoltaic roofing assembly
A photovoltaic roofing assembly comprises a roofing membrane (102), a plurality of photovoltaic modules (104, 106, 108) disposed as a layer on top of the roofing membrane (102), and a plurality of pre-formed spacers, pedestals or supports (112, 114, 116, 118, 120, 122) which are respectively disposed below the plurality of photovoltaic modules (104, 106, 108) and integral therewith, or fixed thereto. Spacers (112, 114, 116, 118, 120, 122) are disposed on top of roofing membrane (102). Membrane (102) is supported on conventional roof framing, and attached thereto by conventional methods. In an alternative embodiment, the roofing assembly may have insulation block (322) below the spacers (314, 314', 315, 315'). The geometry of the preformed spacers (112, 114, 116, 118, 120, 122, 314, 314', 315, 315') is such that wind tunnel testing has shown its maximum effectiveness in reducing net forces of wind uplift on the overall assembly. Such construction results in a simple, lightweight, self-ballasting, readily assembled roofing assembly which resists the forces of wind uplift using no roofing penetrations.
Dinwoodie, T.L.
Dinwoodie, Thomas L. (Berkeley, CA) [Berkeley, CA
Metal Roofing in a "Class" by Itself.
The structural standing seam roof has the advantages of ease of application, low maintenance, and low life-cycle costs. Explains and illustrates how the system's concealed clip attachments are designed so that the roof panels can expand and contract independently of the insulation. (MLF)
Nimtz, Paul D.
Behavior of suspended roofs under blast loading
This work deals with the nonlinear dynamic behavior of initially imperfect dissipative multi-suspended roof systems under blast loading. For various realistic combinations of geometrical, stiffness and damping parameters, the systems do not experience either snapping or large amplitude chaotic motions, contrary to findings reported for single and double suspension roof systems. A nonlinear analysis is employed to establish that global
Ioannis G. Raftoyiannis; Constantine C. Spyrakos; George T. Michaltsos
Roofs--Their Problems and Solutions.
Most roofs are meant to withstand the elements for a period of 20 years; to achieve this goal, however, school officials must believe in a dedicated maintenance program and sell it to their superiors and school boards. Establishment of a school district roof maintenance program is explained. Job qualifications and training methods for an inhouse�
Swentkofske, Carl J.
Building Digest - Roofing, Flooring and Construction Aspects.
This document is a compilation of 9 bulletins. These are: Waffle unit floor/roof; Doubly curved tile roof; Unit frame scaffolding; High strength deformed bars; Sealants for joint and cracks in buildings; Cement as a substitute for lead in jointing C.I. pi...
P. B. Rao J. George S. K. Sharma M. P. Jaisingh V. K. Jain
Building America Best Practices Series, Volume 6: High-Performance Home Technologies: Solar Thermal & Photovoltaic Systems
This guide is was written by PNNL for the US Department of Energy's Building America program to provide information for residential production builders interested in building near zero energy homes. The guide provides indepth descriptions of various roof-top photovoltaic power generating systems for homes. The guide also provides extensive information on various designs of solar thermal water heating systems for homes. The guide also provides construction company owners and managers with an understanding of how solar technologies can be added to their homes in a way that is cost effective, practical, and marketable. Twelve case studies provide examples of production builders across the United States who are building energy-efficient homes with photovoltaic or solar water heating systems.
Baechler, Michael C.; Gilbride, Theresa L.; Ruiz, Kathleen A.; Steward, Heidi E.; Love, Pat M.
A comprehensive numerical model examining the thermal performance of airships
A novel computational model for analyzing the airship's transient thermal performance under different environmental conditions was developed. Radiative heat transfer and natural convection inside the airship were modeled using the control volume method. The Semi-Implicit Method aiming at the Pressure-Linked Equations algorithm was adopted to solve the control equations. Such approach was able to take into account the solar irradiative heat flux, the infrared radiation at different locations, and the convection both inside and outside the airship. The simulation results, showing the detailed distributions of temperature and velocity on the envelope and inside the airship, were in good agreement with the experimental measurements. The influences of solar position and material radiative properties on temperature distribution, as well as natural convective flow inside airship, were further simulated and discussed.
Wang, Y. W.; Yang, C. X.
Thermal Performance of Capillary Pumped Loops Onboard Terra Spacecraft
The Terra spacecraft is the flagship of NASA's Earth Science Enterprise. It provides global data on the state of atmosphere, land and oceans, as well as their interactions with solar radiation and one another. Three Terra instruments utilize Capillary Pumped Heat Transport System (CPHTS) for temperature control: Each CPHTS, consisting of two capillary pumped loops (CPLs) and several heat pipes and electrical heaters, is designed for instrument heat loads ranging from 25W to 264W. The working fluid is ammonia. Since the launch of the Terra spacecraft, each CPHTS has been providing a stable interface temperature specified by the instrument under all modes of spacecraft and instrument operations. The ability to change the CPHTS operating temperature upon demand while in service has also extended the useful life of one instrument. This paper describes the design and on-orbit performance of the CPHTS thermal systems.
Ku, Jentung; Ottenstein, Laura; Butler, Charles D.; Swanson, Theodore; Thies, Diane
Thermal performance evaluation of the Calmac (liquid) solar collector
The procedures used and the results obtained during the evaluation test program on the S. N. 1, (liquid) solar collector are presented. The flat plate collector uses water as the working fluid. The absorber plate is aluminum with plastic tubes coated with urethane black. The glazing consists of .040 in fiberglass reinforced polyester. The collector weight is 78.5 pounds with overall external dimensions of approximately 50.3in. x 98.3in. x 3.8in. The following information is given: thermal performance data under simulated conditions, structural behavior under static loading, and the effects of long term exposure to natural weathering. These tests were conducted using the MSFC Solar Simulator.
Usher, H.
LARGO hot water system thermal performance test report
The thermal performance tests and results on the LARGO Solar Hot Water System under natural environmental conditions is presented. Some objectives of these evaluations are to determine the amount of energy collected, the amount of energy delivered to the household as contributed by solar power supplied to operate the system and auxiliary power to maintain tank temperature at proper level, overall system efficiency and to determine temperature distribution within the tank. The Solar Hot Water system is termed a Dump-type because of the draining system for freeze protection. The solar collector is a single glazed flat plate. An 82-gallon domestic water heater is provided as the energy storage vessel. Water is circulated through the collector and water heater by a 5.3 GPM capacity pump, and control of the pump motor is achieved by a differential temperature controller.
Improving the thermal performance of vinyl-framed windows
Over the last five years, vinyl-framed windows have gained an increased market share in both new and retrofit residential construction. This success has been mainly due to their low manufacturing cost and relatively good thermal performance (i.e., total window U-values with double glazing between 0.50 Btu/h{center_dot}ft{sup 2}{center_dot}{degree}F [2.86 W/m{sup 2}{center_dot}K] and 0.30 Btu/h{center_dot}ft{sup 2}{center_dot}{degree}F [1.70 W/m{sup 2}{center_dot}K]). Turning such windows into ``superwindows,`` windows with a U-value of 0.20 Btu/h{center_dot}ft{sup 2}{center_dot}{degree}F (1.14 W/m{sup 2}{center_dot}K) or less that can act as passive solar elements even on north-facing orientations in cold climates, requires further significant decreases in heat transfer through both the glazing system and the frame/edge. Three-layer glazing systems (those with two low-emissivity coatings and a low-conductivity gas fill) offer center-of-glass U-values as low as 0.10 Btu/h{center_dot}ft{sup 2}{center_dot}{degree}F (0.57 W/m{sup 2}{center_dot}K); such glazings are being manufactured today and can be incorporated into existing or new vinyl frame profiles. This paper focuses on the use of a state-of the-art infrared imaging system and a two-dimensional finite-difference model to improve the thermal performance of commercially available vinyl profiles and glazing edge systems. Such evaluation tools are extremely useful in identifying exactly which components and design features limit heat transfer and which act as thermal short circuits. Such an analysis is not possible with conventional whole-window testing in hot boxes where testing uncertainties with superwindows are often greater than proposed improvements.
Beck, F.A.; Arasteh, D.
Over the last five years, vinyl-framed windows have gained an increased market share in both new and retrofit residential construction. This success has been mainly due to their low manufacturing cost and relatively good thermal performance (i.e., total window U-values with double glazing between 0.50 Btu/h[center dot]ft[sup 2][center dot][degree]F [2.86 W/m[sup 2][center dot]K] and 0.30 Btu/h[center dot]ft[sup 2][center dot][degree]F [1.70 W/m[sup 2][center dot]K]). Turning such windows into superwindows,'' windows with a U-value of 0.20 Btu/h[center dot]ft[sup 2][center dot][degree]F (1.14 W/m[sup 2][center dot]K) or less that can act as passive solar elements even on north-facing orientations in cold climates, requires further significant decreases in heat transfer through both the glazing system and the frame/edge. Three-layer glazing systems (those with two low-emissivity coatings and a low-conductivity gas fill) offer center-of-glass U-values as low as 0.10 Btu/h[center dot]ft[sup 2][center dot][degree]F (0.57 W/m[sup 2][center dot]K); such glazings are being manufactured today and can be incorporated into existing or new vinyl frame profiles. This paper focuses on the use of a state-of the-art infrared imaging system and a two-dimensional finite-difference model to improve the thermal performance of commercially available vinyl profiles and glazing edge systems. Such evaluation tools are extremely useful in identifying exactly which components and design features limit heat transfer and which act as thermal short circuits. Such an analysis is not possible with conventional whole-window testing in hot boxes where testing uncertainties with superwindows are often greater than proposed improvements.
Development of a relative risk model for roof and side fall fatal accidents in underground coal mines in India
A relative risk model for roof and side fall fatal accidents was developed using loglinear analysis of two-way contingency table. A few statistics such as potential fatalities (PF), relative risk of fatalities (RRF) and safety measure effectiveness (SME) were derived which can be used as key safety performance indicators of roof and side fall accidents in underground mines. The model
J. Maiti; Vivek V. Khanzode
A guidebook for insulated low-slope roof systems. IEA Annex 19, Low-slope roof systems: International Energy Agency Energy Conservation in Buildings and Community Systems Programme
Low-slope roof systems are common on commercial and industrial buildings and, to a lesser extent, on residential buildings. Although insulating materials have nearly always been a component of low-slope roofs, the amount of insulation used has increased in the past two decades because of escalation of heating and cooling costs and increased awareness of the need for energy conservation. As the amount of insulation has increased, the demand has intensified for design, installation, and maintenance information specifically for well-insulated roofs. Existing practices for design, installation, and maintenance of insulated roofs have evolved from experience. Typically, these practices feature compromises due to the different properties of materials making up a given roof system. Therefore, they should be examined from time to time to ensure that they are appropriate as new materials continue to enter the market and as the data base on existing systems expands. A primary purpose of this International Energy Agency (IEA) study is to assess current roofing insulation practices in the context of an accumulating data base on performance.
Thermal performance characteristic comparison between flip-chip wirebond ceramic multichip modules
Multichip module (MCM) thermal performance for flip chip and wirebond (WE) die attach packages are evaluated using four chip, uniform size ceramic substrates. Thermal characteristics of each module are evaluated by conduction parametric analyser of individual module element properties and dimensions. Thermal performance is evaluated for conditions ranging from low air now and no heat sink to high air flow
T. D. Yuan
Thermal radiant exitance model performance: Soils and forests
Models of surface temperatures of two land surface types based on their energy budgets were developed to simulate the effects of environmental factors on thermal radiant exitance. The performance of these models is examined in detail. One model solves the non-linear differential equation for heat diffusion in solids using a set of submodels for surface energy budget components. The model performance is examined under three desert conditions thought to be a strong test of the submodels. The accuracy of the temperature predictions and submodels is described. The accuracy of the model is generally good but some discrepancies between some of the submodels and measurements are noted. The sensitivity of the submodels is examined and is seen to be strongly controlled by interaction and feedback among energy components that are a function of surface temperature. The second model simulates vegetation canopies with detailed effects of surface geometry on radiant transfer in the canopy. Foliage solar absorption coefficients are calculated using a radiosity approach for a three layer canopy and long wave fluxes are modeled using a view factor matrix. Sensible and latent heat transfer through the canopy are also simulated using, nearby meteorological data but heat storage in the canopy is not included. Simulations for a coniferous forest canopy are presented and the sensitivity of the model to environmental inputs is discussed.
Balick, L.K. [EG& G Energy Measurements Inc., Las Vegas, NV (United States); Smith, J.A. [NASA/Goddard Space Flight Center, Greenbelt, MD (United States). Lab. for Terrestrial Physics
Application of Spray Foam Insulation Under Plywood and Oriented Strand Board Roof Sheathing
Unvented roof strategies with open cell and closed cell spray polyurethane foam insulation sprayed to the underside of roof sheathing have been used since the mid-1990's to provide durable and efficient building enclosures. However, there have been isolated moisture related incidents reported anecdotally that raise potential concerns about the overall hygrothermal performance of these systems. The incidents related to rainwater leakage and condensation concerns. Condensation concerns have been extensively studied by others and are not further discussed in this report. This project involved hygrothermal modeling of a range of rainwater leakage and field evaluations of in-service residential roofs using spray foam insulation. All of the roof assemblies modeled exhibited drying capacity to handle minor rainwater leakage. All field evaluation locations of in-service residential roofs had moisture contents well within the safe range for wood-based sheathing. Explorations of eleven in-service roof systems were completed. The exploration involved taking a sample of spray foam from the underside of the roof sheathing, exposing the sheathing, then taking a moisture content reading. All locations had moisture contents well within the safe range for wood-based sheathing. One full-roof failure was reviewed, as an industry partner was involved with replacing structurally failed roof sheathing. In this case the manufacturer's investigation report concluded that the spray foam was installed on wet OSB based on the observation that the spray foam did not adhere well to the substrate and the pore structure of the closed cell spray foam at the ccSPF/OSB interface was indicative of a wet substrate.
Grin, A.; Smegal, J.; Lstiburek, J.
COMMIX analysis of four constant flow thermal upramp experiments performed in a thermal hydraulic model of an advanced LMR
The three-dimensional thermal hydraulics computer code COMMIX-1AR was used to analyze four constant flow thermal upramp experiments performed in the thermal hydraulic model of an advanced LMR. An objective of these analyses was the validation of COMMIX-1AR for buoyancy affected flows. The COMMIX calculated temperature histories of some thermocouples in the model were compared with the corresponding measured data. The conclusions of this work are presented. 3 refs., 5 figs.
Yarlagadda, B.S.
Performance of modern products for underlay in residential buildings
The performance of some modern products intended for underlayment in steep roofs was studied. Properties considered were durability against thermal degradation and against water. Also the effect of combinations of water, heat and cold were studied as well as natural ageing. The effect of water flowing over installed products was also studied. The studied products were foils or sheets, most
T. Lindfors; F. Bj�rk
Signal processing core for high performance thermal imaging
In order to fully exploit emerging 3rd generation infrared detector technology, very high performance signal processing electronics are required in order to process in real-time, the vast amount of data that can be generated. This paper describes SELEX Sensors and Airborne System's most recent developments based upon the existing Sensor Integrated Modular Architecture (SiGMA) thermal imager. The key advances described in this paper include a modular architecture approach allowing physical separation of the processing core from the detector and proximity electronics, the miniaturisation of the processing electronics and the introduction of a solid state micro-scan mechanism which builds upon concepts developed during the company's previous work with uncooled infrared detector technology. The sensor architecture is initially designed to operate with the SELEX S&AS developed Hawk infrared detector, a medium waveband 640*512 element CMT array on a 16 micron pitch, but will also be compatible with the emerging Albion detector arrays, a medium waveband 1024*768 element CMT array on a 16 micron pitch and a long waveband 640*512 element CMT array on a 24 micron pitch. Other areas described are the development of advanced image processing algorithms including non-linear correction for display optimisation.
Lawrence, M.; Ashley, S. F.; Lupton, M.; McEwen, R. K.; Wilson, M.
Thermal performance of residential duct systems in basements
There are many unanswered questions about the typical effects of duct system operation on the infiltration rates and energy usage of single- family residences with HVAC systems in their basements. In this paper, results from preliminary field studies and computer simulations are used to examine the potential for improvements in efficiency of air distribution systems in such houses. The field studies comprise thermal and flow measurements on four houses in Maryland. The houses were found to have significant envelope leakage, duct leakage, and duct conduction losses. Simulations of a basement house, the characteristics of which were chosen from the measured houses, were performed to assess the energy savings potential for basement house. The simulations estimate that a nine percent reduction in space conditioning energy use is obtained by sealing eighty percent of the duct leaks and insulating ducts to an R-value of 0.88 {degree}C{center_dot}m{sup 2}/W (5{degree}F{center_dot}ft{sup 2}{center_dot}h/BTU) where they are exposed in the basement. To determine the maximum possible reduction m energy use, simulations were run with all ducts insulated to 17.6 {degree}C{center_dot}m{sup 2}/W (100 {degree}F{center_dot}ft{sup 2}{center_dot}h/BTU) and with no duct leakage. A reduction of energy use by 14% is obtained by using perfect ducts instead of nominal ducts.
Treidler, B.; Modera, M.
Thermal performance of a multi-evaporator loop heat pipe with thermal masses and thermal electrical coolers
This paper describes thermal performance of a loop heat pipe (LHP) with two evaporators and two condensers in ambient testing. Each evaporator has an outer diameter of 15mm and a length of 76mm, and has an integral compensation chamber (CC). An aluminum mass of 500 grams is attached to each evaporator to simulate the instrument mass. A thermal electric cooler (TEC) is installed on each CC to provide heating as well as cooling for CC temperature control. A flow regulator is installed in the condenser section to prevent vapor from going back to the evaporators in the event that one of condenser is fully utilized. Ammonia was used ad the working fluid. Tests conducted included start-up, power cycle, heat load sharing, sink temperature cycle, operating temperature control with TECs, and capillary limit tests. Experimental data showed that the loop could start with a heat load of less than 1OW even with added thermal masses. The loop operated stably with even and uneven evaporator heat loads, and even and uneven condenser sink temperatures. The operating temperature could be controlled within +/-0.5K of the set point temperature using either or both TECs, and the required TEC control heater power was less than 2W under most test conditions. Heat load sharing between the two evaporators was also successfully demonstrated. The loop had a heat transport capability of 120W to 140W, and could recover from a dry-out when the heat load was reduced. The 500-gram aluminum mass on each evaporator had a negligible effect on the loop operation. Existing LHPs servicing the orbiting spacecraft have a single evaporator with an outer diameter of about 25mm. Important performance characteristics demonstrated by this LHP included: 1) Operation of an LHP with 15mm diameter evaporators; 2) Robustness and reliability of an LHP with multiple evaporators and multiple condensers under various test conditions; 3) Heat load sharing among LHP evaporators; 4) Effectiveness of TECs in controlling the LHP operating temperature; and 5) Effectiveness of the flow regulator in preventing vapor from going back the evaporators.
Ku, Jentung; Ottenstein, Laura; Birur, Gajanana
Suspension roof support. Progress report 1
How the Bureau of Mines has adapted suspension supports to conditions found in American coal mines is given in an intensive attack upon the problem of preventing mine roof and rock from falling prematurely.
E. Thomas; A. J. Barry; A. Metcalfe
Research on Integrated Solar Collector Roof Structures.
Several prototype models for an integrated solar collector-roof structure member are described and operating data are given. Fabrication and costs are briefly discussed. The prototypes include both liquid and air cooled models.
J. D. Balcomb J. C. Hedstrom S. W. Moore K. C. Herr
Rectilinear building roof contour extraction based on snakes and dynamic programming
This paper presents a method for extracting building roof contours from digital images collected over urban landscapes. The proposed method utilizes an energy function based on snakes that represents building roof contours in digital images and is optimized with a dynamic programming (DP) algorithm. Because most building roof contours are characterized by rectilinear sides that intercept at right angles, appropriate geometric constraints are enforced in the previously reported snake-based energy function. The main advantage of using the DP algorithm for optimizing the proposed snake-based energy function is its better radius of convergence compared to that typically obtained in the original solution based on variational approaches. Experimental evaluation, which included visual inspections and numerical analyses, was performed using real data, and the obtained results demonstrated that the proposed method has significant potential for successfully extracting building roof contours from digital images.
Fazan, Antonio Juliano; Dal Poz, Aluir Porf�rio
Performance assessment of low pressure nuclear thermal propulsion
An increase in Isp for nuclear thermal propulsion systems is desirable for reducing the propellant requirements and cost of future applications, such as the Mars Transfer Vehicle. Several previous design studies have suggested that the Isp could be increased substantially with hydrogen dissociation/recombination. Hydrogen molecules (H2), at high temperatures and low pressures, will dissociate to monatomic hydrogen (H). The reverse process (i.e., formation of H2 from H) is exothermic. The exothermic energy in a nozzle increases the kinetic energy and therefore, increases the Isp. The low pressure nuclear thermal propulsion system (LPNTP) system is expected to maximize the hydrogen dissociation/recombination and Isp by operating at high chamber temperatures and low chamber pressures. The process involves hydrogen flow through a high temperature, low pressure fission reactor, and out a nozzle. The high temperature (approximately 3000 K) of the hydrogen in the reactor is limited by the temperature limits of the reactor material. The minimum chamber pressure is about 1 atm because lower pressures decrease the engines thrust to weight ratio below acceptable limits. This study assumes that hydrogen leaves the reactor and enters the nozzle at the 3000 K equilibrium dissociation level. Hydrogen dissociation in the reactor does not affect LPNTP performance like dissociation in traditional chemical propulsion systems, because energy from the reactor resupplies energy lost due to hydrogen dissociation. Recombination takes place in the nozzle due primarily to a drop in temperature as the Mach number increases. However, as the Mach number increases beyond the nozzle throat, the static pressure and density of the flow decreases and minimizes the recombination. The ideal LPNTP Isp at 3000 K and 10 psia is 1160 seconds due to the added energy from fast recombination rates. The actual Isp depends on the finite kinetic reaction rates which affect the amount of monatomic hydrogen recombination before the flow exits the nozzle. A LPNTP system has other technical issues (e.g. flow instability and two-phase flow) besides hydrogen dissociation/recombination which affect the systems practicality. In this study, only the effects of hydrogen dissociation/recombination are examined.
Gerrish, Harrold P., Jr.; Doughty, Glen E.
Thermal performance of closed two-phase thermosyphon using nanofluids
Nanofluids, stabilized suspensions of nanoparticles typically <100 nm in conventional fluids, are evolving as potential enhanced heat transfer fluids due to their improved thermal conductivity, increase in single phase heat transfer coefficient and significant increase in critical boiling heat flux. In the present paper, we investigate the overall thermal resistance of closed two-phase thermosyphon using pure water and various water
Sameer Khandekar; Yogesh M. Joshi; Balkrishna Mehta
Thermal performance of metal-clad fiber Bragg grating sensors
We demonstrate the higher temperature sensitivity of a fiber Bragg grating (FBG) sensor when it is clad with a metal of a large thermal expansion coefficient. With lead (solder) cladding, the sensitivity of Bragg wavelength shift can be enhanced by about five (four) times. A theoretical model was adopted to show quite consistent results. It was found that thermal annealing
Gang-Chih Lin; Likarn Wang; C. C. Yang; M. C. Shih; T. J. Chuang
Thyristor Valve Gapless Arrester Element Lifetime Performance and Thermal Stability
For the purpose of developing thyristor valve gapless arrester, a ZnO element was developed and examination was conducted on such characteristics of gapless arrester as life characteristic, thermal runaway characteristic and surge withstand capability, these being essential to rational design of thyristor valve gapless arrester. Especially for evaluating the life characteristic and thermal runaway, a small-scale 3- phase bridge thyristor
H. Nishikawa; M. Sukehara; T. Yoshida; S. Kobayashi; T. Takahashi; N. Amiji; T. Sasaki; S. Tanabe
Mechanisms governing the performance of thermal barrier coatings
Thermal barrier coatings (TBCs) are now used on hot section components in most commercial turbine engines. They are used to enhance the temperature differential between the gas and the underlying metal surfaces. They comprise several layers designed to simultaneously provide thermal and oxidation protection. They have microstructures which afford sufficient strain tolerance that they remain attached despite severe thermomechanical cycling.
P. K. Wright; A. G. Evans
In a cylindrical wall storage tank for containing a liquid, said tank is described having a floor, a floatable roof supportable by said contained liquid, said roof including a peripheral seal for engaging the cylindrical wall to maintain a fluid-tight sliding seal therewith, and support means associated with said roof including, the improvement in said tank of, at least one cylindrical guide sleeve extending downwardly from said floatable roof; a shoe depending laterally from said at least one cylindrical guide sleeve's lower end for engaging the tank floor when the level of contained liquid is insufficient to support said floatable roof, said shoe having means forming a passage there through to register a support column and, an elongated support column removably positioned in said at least one cylindrical guide sleeve, of being sufficient length to extend downward beyond the shoe to engage the tank floor, whereby to sustain the floatable roof a predetermined distance above said floor after the contained liquid has drained from the tank.
Vaughn, L.G.
Thermal and hydraulic performance of a sieve tray direct contact heat exchanger
Experiments investigating the thermal and hydraulic performance of a sieve tray direct contact heat exchanger (DCHX) were conducted using a 275 \\/SUP o\\/ geothermal fluid as an energy source and different hydrocarbons as working fluids. The baseline performance tests with the direct contact unit were conducted with isobutane. The thermal performance of the unit met or exceeded the design goals
G. L. Mines; D. J. Wiggins
Thermal and hydraulic performance of a sieve-tray direct-contact heat exchanger
Experiments investigating the thermal and hydraulic performance of a sieve tray direct contact heat exchanger (DCHX) were conducted using a 275° geothermal fluid as an energy source and different hydrocarbons as working fluids. The baseline performance tests with the direct contact unit were conducted with isobutane. The thermal performance of the unit met or exceeded the design goals for individual
Multi-Objective Optimization of Residential Building Roof Layer Thickness for Minimization of Heat Entering the Room Using FEM and Grey Relational Analysis
In this work, a multi objective optimization on roof layer thickness has been carried out through Taguchi based grey relational analysis technique. Conventional type of residential building roof was changed by a modified pattern of roof having layers namely concrete, phase change material, wood wool and weathering tile and its performance on heat insulation have been studied. In this study, the optimum thickness of roof layers was determined for minimum heat gain through roof by grey relational analysis technique. The thickness of various roof layers were considered as control parameters and varied through five levels of values. For this objective, Taghuchi's L25 orthogonal array has been employed and the performance on heat insulation was studied through finite element analysis (FEA) technique. The FEA simulation on heat transfer across the roof has also been validated with the experimental results and found that it is having a good agreement. The optimized roof reduces the heat gain and temperature by 30 % and 3 �C respectively in comparison with the conventional type of roof. Also from this study, it was identified that the wood wool is the most predominant roof layer that controls the heat gain into the room.
Prakash, D.; Ravikumar, P.
A one-year non-cost extension has been granted for this project. In this quarter, the field, theoretical and programming works have been performed toward achieving the research goals set in the proposal. The main accomplishments in this quarter included: (1) laboratory tests have been conducted, (2) with the added trendline analysis method, the accuracy of the data interpretation methodology will be improved and the interfaces and voids can be more reliably detected, (3) method to use torque to thrust ratio as indicator of rock relative hardness has also been explored, and (3) about 80% of the development work for the roof geology mapping program, MRGIS, has completed and a special version of the program is in the field testing stage.
Syd S. Peng
Comparison of the thermal performance of double U-pipe borehole heat exchangers measured in situ
A borehole heat exchanger is a ground heat exchanger devised for the extraction or injection of thermal energy from\\/into the ground. The thermal performance of a borehole heat exchanger can be assessed with a response test. The response test method allows the in situ determination of the thermal conductivity of the ground in the vicinity of a borehole heat exchanger,
D. Pahud; B. Matthey
Performance modeling of the Early External Active Thermal Control System for the International Space Station
The Early External Active Thermal Control System (EEATCS) is used to perform the cooling of the US Laboratory (USL) during early assembly stages of the International Space Station (ISS) to support assured early research (AER). It will provide the ability to transport the thermal load generated by the USL to space by thermal radiation via two photovoltaic radiators (PVR). The
Study of thermal conductivity, permeability, and adsorption performance of consolidated composite activated carbon adsorbent for refrigeration
Composite adsorbents, comprising activated carbon and expanded natural graphite, have been developed, and their thermal conductivity, permeability and adsorption performance were tested. The thermal conductivity varied with the ratio of activated carbon to expanded natural graphite. Thermal conductivity increased as the ratio of expanded graphite increased. Considering that the density of activated carbon for the composite adsorbent should not be
L. W. Wang; Z. Tamainot-Telto; R. Thorpe; R. E. Critoph; S. J. Metcalf; R. Z. Wang
Performance of Thermal Insulation Containing Microencapsulated Phase Change Material
The objective of this study is dynamic thermal performance microencapsulated phase change material (PCM) blended with loose-fill cellulose insulation. Dynamic hot-box testing and heat-flux measurements have been made for loose-fill cellulose insulation with and without uniformly distributed microencapsulated PCM. The heat flux measurements were made with a heat-flow-meter (HFM) apparatus built in accordance with ASTM C 518. Data were obtained for 1.6 lb{sub m}/ft{sup 3} cellulose insulation containing 0 to 40 wt% PCM. Heat-flux data resulting from a rapid increase in the temperature on one side of a test specimen initially at uniform temperature were analyzed to access the effect of PCM on total heat flow. The heat flux was affected by the PCM for about 100 minutes after the temperature increase. The total heat flow during this initial period decreased linearly with PCM content from 6.5 Btu/ft{sup 2} at 0% PCM to 0.89 Btu/ft{sup 2} for 40 wt% PCM. The cellulose insulation with PCM discharged heat faster than the untreated cellulose when the hot-side temperature of the test specimen was reduced. In addition, hot-box apparatus built in accordance with ASTM C 1363 was utilized for dynamic hot-box testing of a wood stud wall assembly containing PCM-enhanced cellulose insulation. Experimental data obtained for wood-frame wall cavities containing cellulose insulation with PCM was compared with results obtained from cavities containing only cellulose insulation.
Kosny, Jan [ORNL; Yarbrough, David [R & D Services; Syed, Azam M [ORNL
Interim procedure to measure the thermal performance of window systems
The purpose of the report is to review the current sources of information on U-values and to describe the state of thermal test methods used for windows in order to provide the Bonneville Power Administration with some general guidelines in the application of thermal test data for use in the Model Conservation Standards (MCS) by the Northwest Power Planning Council. At present, considerable controversy exists in the window industry regarding the thermal testing of windows, therefore no consensus-based standards are available.
McCabe, M.E.; Goss, W.P.
Thermal Performance of a Multi-Evaporator Loop Heat Pipe with Thermal Masses and Thermoelectric Coolers
This paper describes thermal performance of a loop heat pipe (LHP) with two evaporators and two condensers in ambient testing. Each evaporator has an outer diameter of 15mm and a length of 76mm, and has an integral compensation chamber (CC). An aluminum mass of 500 grams is attached to each evaporator to simulate the instrument mass. A thermoelectric cooler (TEC) is installed on each CC to provide heating as well as cooling for CC temperature control. A flow regulator is installed in the condenser section to prevent vapor from going back to the evaporators in the event that one of the condensers is fully utilized. Ammonia was used as the working fluid. Tests conducted included start-up, power cycle, heat load sharing, sink temperature cycle, operating temperature control with TECs, and capillary limit tests. Experimental data showed that the loop could start with a heat load of less than 10W even with added thermal masses. The loop operated stably with even and uneven evaporator heat loads, and even and uneven condenser sink temperatures. The operating temperature could be controlled within +/- 0.5K of the set point temperature using either or both TECs, and the required TEC control heater power was less than 2W under most test conditions. Heat load sharing between the two evaporators was also successfully demonstrated. The loop had a heat transport capability of 120W to 140W, and could recover from a dry-out when the heat load was reduced. The 500-gram aluminum mass on each evaporator had a negligible effect on the loop operation. Existing LHPs servicing orbiting spacecraft have a single evaporator with an outer diameter of about 25mm. Important performance characteristics demonstrated by this LHP included: 1) Operation of an LHP with 15mm diameter evaporators; 2) Robustness and reliability of an LHP with multiple evaporators and multiple condensers under various test conditions; 3) Heat load sharing among LHP evaporators; 4) Effectiveness of TECs in controlling the LHP operating temperature; and 5 ) Effectiveness of the flow regulator in preventing vapor from going back the evaporators.
Ku, Jen-Tung; Ottenstein, Laura; Birur, Gajanana
The Thermal Performance of Several Australian Fibrous Insulating Materials
The thermal conductivity of fibrous insulation materials most com monly used in Australian buildings has been measured over a range of typical densi ties and thicknesses. Correlating equations for thermal conductivity as a function of density have been derived for each material.The materials studied have included batt or blanket form (low-density fibreglass, sheep's wool, and polyester fibre) and loose-fill form
J. G. Symons; R. E. Clarke; J. V. Peirce
Influence of temperature and non-elastic behaviour on roof collapse and subsidence resulting from underground coal gasification
The effects of various factors on the roof collapse and subsidence resulting from the development of an underground coal gasification cavity are examined. These factors include drying of the surrounding rocks, thermal loading, thermal softening and time-dependent rock mechanical properties. These investigations have been conducted with the aid of a 2-D plane strain finite element model. It is shown that drying effects are largely offset by the resulting tendency towards roof collapse, while thermal stress effects are largely negated by thermal softening. For elastic overburden, roof collapse has the major influence on surface subsidence. Creep of the overburden increases the surface subsidence both in terms of vertical movements and horizontal strains.
Jegbefume, E.U.; Thompson, T.W.
Thermo-Oxidative Stability of High Performance Composites under Thermal Cycling Conditions
Thermo-oxidative stability of high performance composites was investigated under thermal cycling conditions between room and 177�C curing temperature. For the analysis of thermal cycling experimental results, an equivalent cycle time (ECT) was developed by applying degradation-reaction kinetic theories to thermal-cycling conditions. Applying this methodology to the weight loss measurements of composite specimens, thermal cycling was found to exhibit a slower
Sang-Ho Lee; Jae-Do Nam; Kyujong Ahn; Ki-Mo Chung; James C. Seferis
Surface heat budget on green roof and high reflection roof for mitigation of urban heat island
In this study, the surface temperature, net radiation, water content ratio, etc., of green roofs and high reflection roofs are observed. The heat and water budget are compared to each other. In the daytime, the temperature of the cement concrete surface, the surface with highly reflective gray paint, bare soil surface, green surface and the surface with highly reflective white
Hideki Takebayashi; Masakazu Moriyama
Green Roofs for a Green Town: Possibilities of Green Roof Implementation in the Town of Normal
Green roofs have been growing in popularity throughout the world. Scientists have been studying them since the 1980�s. This research project reviews the literature regarding both the benefits and barriers to green roof construction and management. Policies around the nation are then examined and analyzed. Suggestions are made regarding possible additions to the local Stormwater Management Policy that would emphasize
Sihau Lindsey
Green roofs for a drier world: Effects of hydrogel amendment on substrate and plant water status.
Climate features of the Mediterranean area make plant survival over green roofs challenging, thus calling for research work to improve water holding capacities of green roof systems. We assessed the effects of polymer hydrogel amendment on the water holding capacity of a green roof substrate, as well as on water status and growth of Salvia officinalis. Plants were grown in green roof experimental modules containing 8cm or 12cm deep substrate (control) or substrate mixed with hydrogel at two different concentrations: 0.3 or 0.6%. Hydrogel significantly increased the substrate's water content at saturation, as well as water available to vegetation. Plants grown in 8cm deep substrate mixed with 0.6% of hydrogel showed the best performance in terms of water status and membrane integrity under drought stress, associated to the lowest above-ground biomass. Our results provide experimental evidence that polymer hydrogel amendments enhance water supply to vegetation at the establishment phase of a green roof. In particular, the water status of plants is most effectively improved when reduced substrate depths are used to limit the biomass accumulation during early growth stages. A significant loss of water holding capacity of substrate-hydrogel blends was observed after 5months from establishment of the experimental modules. We suggest that cross-optimization of physical-chemical characteristics of hydrogels and green roof substrates is needed to improve long term effectiveness of polymer-hydrogel blends. PMID:24867709
Savi, Tadeja; Marin, Maria; Boldrin, David; Incerti, Guido; Andri, Sergio; Nardini, Andrea
Thermal performance of a photographic laboratory process: solar hot water system
The thermal performance of a solar process hot water system is described. The system was designed to supply 22,000 liters (5,500 gallons) per day of 66 C (150 F) process water for photographic processing. The 328 sq m (3,528 sq. ft.) solar field has supplied 58% of the thermal energy for the system. Techniques used for analyzing various thermal values are given. Load and performance factors and the resulting solar contribution are discussed.
Walker, J.A.; Jensen, R.N.
SOLSTEP: A Computer Model for Predicting the Thermodynamic and Economic Performance of Solar Thermal Power Plants.
A thermodynamic and economic performance analysis code, SOLSTEP, was developed to facilitate the evaluation of solar thermal power plant designs. The code conducts a time step simulation of the plant thermodynamic performance using actual recorded meteoro...
S. P. Bird
Comparison of the Thermal Performance of Two Pressure and Puffer Circuit Breakers.
Two pressure interrupter tests were performed at Liverpool on a model circuit breaker which was specifically designed to enable sophisticated arc diagnostics to be used. Both pressure and thermal reignition performance measurements were undertaken. Tests ...
D. Shimmin S. M. G. Ali H. M. Ryan G. R. Jones P. Headley
Comparative Analysis of Face Recognition Performance With Visible and Thermal Infrared Imagery.
We present a comprehensive performance analysis of multiple appearance-based face recognition methodologies, on visible and thermal infrared imagery. We compare algorithms within and between modalities in terms of recognition performance, false alarm rate...
D. A. Socolinsky A. Selinger
Thermal Performance of Idealized Double Windows, Unvented. Research Paper No. 223.
The testing plans, procedures, and results of an experiment are revealed concerning the thermal performance and variable factors of unvented double windows, their heat transmission and inner surface temperature. Data are given to help improve the design and development of standards for the thermal performance of windows. Building humidity, window�
Christensen, G.; And Others
Optimization and Thermal Performance Assessment of Pin-Fin Heat Sinks
In this work, the heat transfer and fluid flow analyses are employed to optimize the geometry of the pin-fin heat sinks. An entropy generation minimization method is employed to optimize the overall thermal performance and behavior of pin-fin heat sinks. The performance of the heat sinks is determined by its thermal resistance and pressure drop, since they significantly influence the
Z. S. Abdel-Rehim
Experimental investigation of a flat plate heat pipe performance using IR thermal imaging camera
This paper presents results and analysis of an experimental investigation into determining the thermal performance of a flat plate heat pipe using infra red (IR) thermal imaging camera. Steady state and transient temperature distribution of the evaporator surface of the flat plate heat pipe were measured using a single heat source with varied heat flux inputs. For performance comparison, the
R. Boukhanouf; A. Haddad; M. T. North; C. Buffone
ATS-6 engineering performance report. Volume:Program and systems summaries: Mechanical and thermal details
The overall mission and spacecraft systems, testing, and operations are summarized. The mechanical subsystems are reviewed, encompassing mechanical design requirements; separation and deployment mechanisms; design and performance evaluation; and the television camera reflector monitor. Thermal control and contamination are discussed in terms of thermal control subsystems, design validation, subsystems performance, the advanced flight experiment, and the quartz-crystal microbalance contamination monitor.
Wales, R. O. (editor)
Antenna performance predictions of a radio telescope subject to thermal perturbations
Antenna performance predictions and calibration times are estimated on a 37 m diameter radio telescope subject to thermal perturbations. The telescope is designed to operate at frequencies up to 325 GHz with a one-way performance requirement of 1 dB loss in gain accounting for fabrication, alignment, gravity and thermal errors. Thermal gradients acting over the antenna structure due to diurnal air temperature variations are a significant contributor to degradations in antenna performance. Integrated thermal-structural-optical analyses were performed to predict antenna performance as a function of the diurnal variations. Based on the results, design requirements were imposed on the radome thermal control system and the rate of calibration of the hexapod mounted subreflector.
Doyle, Keith B.
Thermal Performance of Composite Flexible Blanket Insulations for Hypersonic Aerospace Vehicles
This paper describes the thermal performance of a Composite Flexible Blanket Insulation (C.F.B.I.) considered for potential use as a thermal protection system or thermal insulation for future hypersonic vehicles such as the National Aerospace Plane (N.A.S.P.). Thermophysical properties for these insulations were also measured including the thermal conductivity at various temperatures and pressures and the emissivity of the fabrics used in the flexible insulations. The thermal response of these materials subjected to aeroconvective heating from a plasma arc is also described. Materials tested included two surface variations of the insulations, and similar insulations coated with a Protective Ceramic Coating (P.C.C.). Surface and backface temperatures were measured in the flexible insulations and on Fibrous Refractory Composite Insulation (F.R.C.I.) used as a calibration model. The uncoated flexible insulations exhibited good thermal performance up to 35 W/sq cm. The use of a P.C.C. to protect these insulations at higher heating rates is described. The results from a computerized thermal analysis model describing thermal response of those materials subjected to the plasma arc conditions are included. Thermal and optical properties were determined including thermal conductivity for the rigid and flexible insulations and emissivity for the insulation fabrics. These properties were utilized to calculate the thermal performance of the rigid and flexible insulations at the maximum heating rate.
Kourtides, Demetrius A.
The Submillimeter-Wave Astronomy Satellite: On-Orbit Thermal Performance and Design Retrospective
A large telescope aperture, stringent thermal stability and temperature range requirements, and a passively-cooled 1500K module presented major challenges in thermal design and hardware fabrication of this Small Explorer satellite. This paper reviews briefly the thermal design of the SWAS science instrument, and examines the first three months of on-orbit thermal history. Measured temperatures for both the science payload and the spacecraft module and solar arrays are compared with those predicted by the correlated analytical model. Similarities and differences are interpreted in terms of the major uncertainties remaining after thermal-balance testing, especially those of MLI performance and telescope aperture properties. Review of the thermal model adequacy and thermal design verification are included to suggest improvements in the thermal design process for future missions.
Boyd, David A.; Ousley, Wes; Fantano, Louis
A large telescope aperture, stringent thermal stability and temperature range requirements, and a passively-cooled 150 K module presented major challenges in thermal design and hardware fabrication of this Small Explorer satellite. This paper reviews briefly the thermal design of the SWAS science instrument, and examines the first three months of on-orbit thermal history. Measured temperatures for both the science payload and the spacecraft module and solar arrays are compared with those predicted by the correlated analytical model. Similarities and differences are interpreted in terms of the major uncertainties remaining after thermal-balance testing, especially those of MLI performance and telescope aperture properties. Review of the thermal model adequacy and thermal design verification are included to suggest improvements in the thermal design process for future missions.
Boyd, David A.; Ousley, Wes; Fantano, Louis; Powers, Edward I. (Technical Monitor)
Performance Testing of Thermal Interface Filler Materials in a Bolted Aluminum Interface Under Thermal/Vacuum Conditions
A thermal interface material is one of the many tools often used as part of the thermal control scheme for space-based applications. Historically, at Marshall Space Flight Center, CHO-THERM 1671 has primarily been used for applications where an interface material was deemed necessary. However, numerous alternatives have come on the market in recent years. It was decided that a number of these materials should be tested against each other to see if there were better performing alternatives. The tests were done strictly to compare the thermal performance of the materials relative to each other under repeatable conditions and do not take into consideration other design issues, such as off-gassing, electrical conduction, isolation, etc. The purpose of this Technical Memorandum is to detail the materials tested, test apparatus, procedures, and results of these tests. The results show that there are a number of better performing alternatives now available.
Glasgow, S. D.; Kittredge, K. B.
Solar thermal electric performance and prospects: The view from Luz
This article examines a solar thermal-electric power plant by Luz International Limited. The article's topics include legislation, tax credits, and other incentives for the development of solar energy technology, the technology used, the benefits of solar electricity, the potential for solar energy, limitations and current barriers, and future development.
M. Lotker; D. Kearney
Improved cooler performance using spectrally selective thermal coatings
The GOES Imager and Sounder Radiant Coolers are controlled to run at temperatures around 100 K. Future instruments may have added detectors and additional detector heat that will cause the radiant cooler temperatures to rise if design changes are not implemented. Thermal analyses show that lowering the radiant energy from the cooler sun shield (temperatures range between 170 K and
Dave Neuberger; Norm Ackerman; George Harris
Meaningful performance evaluation conditions for fire service thermal imaging cameras
Thermal imaging cameras (TIC) are rapidly becoming integral equipment for the fire service for use in structure fires and other emergencies. The Building and Fire Research Laboratory (BFRL) at the National Institute of Standards and Technology has conducted research to establish test conditions that best represent the environment in which TIC are used. Firefighters may use TIC for field operations
Francine Amon; Anthony Hamins; Nelson Bryner; Justin Rowe
Performance of thermal barrier coatings in high heat flux environments
Thermal barrier coatings were exposed to the high temperature and high heat flux produced by a 30 kW plasma torch. Analysis of the specimen heating rates indicates that the temperature drop across the thickness of the 0.038 cm ceramic layer was about 1100 \\
The effect of roof strength on reducing occupant injury in rollovers.
Roof crush occurs and potentially contributes to serious or fatal occupant injury in 26% of rollovers. It is likely that glazing retention is related to the degree of roof crush experienced in rollover accidents. Occupant ejection (including partial ejection) is the leading cause of death and injury in rollover accidents. In fatal passenger car accidents involving ejection, 34% were ejected through the side windows. Side window glass retention during a rollover is likely to significantly reduce occupant ejections. The inverted drop test methodology is a test procedure to evaluate the structural integrity of roofs under loadings similar to those seen in real world rollovers. Recent testing on many different vehicle types indicates that damage consistent with field rollover accidents can be achieved through inverted drop testing at very small drop heights. Drop test comparisons were performed on 16 pairs of vehicles representing a large spectrum of vehicle types. Each vehicle pair includes a production vehicle and a vehicle with a reinforced roof structure dropped under the same test conditions. This paper offers several examples of post-production reinforcements to roof structures that significantly increase the crush resistance of the roof as measured by inverted drop tests. These modifications were implemented with minimal impact on vehicle styling, interior space and visual clearances. The results of these modifications indicate that roof crush can be mitigated by nearly an order of magnitude, as roof crush was reduced by 44-91% with only a 1-2.3% increase in vehicle weight. Additionally, this paper analyzes the glazing breakage patterns in the moveable tempered side windows on the side adjacent to the vehicle impact point in the inverted drop tests. A comparison is made between the production vehicles and the reinforced vehicles in order to determine if the amount roof crush is related to glazing integrity in the side windows. Lastly, two drop test pairs, performed with Hybrid III test dummies, indicates that the reduction of roof crush resulted in a direct reduction in neck loading and therefore an increase in occupant protection. PMID:15850089
Herbst, Brian; Forrest, Steve; Orton, Tia; Meyer, Steven E; Sances, Anthony; Kumaresan, Srirangam
Preparation and performance of thermal insulation energy saving coating materials for exterior wall.
Nano zinc oxide with a high refractive index has good thermal reflection performance, hollow glass microspheres have good thermal reflection and insulation performance, and sepiolite nanofibers with many nanostructural pores have good thermal insulation performance. The dispensability of nano zinc oxide in coating materials was improved by optimizing surface silane coupling agent modification process, leading to the good thermal reflection performance. The thermal insulation performance was improved by hollow glass microspheres and sepiolite nanofibers. On this basis, the thermal insulation coating materials were prepared by exploring the effect of amount, complex mode, and other factors of the above three kinds of functional fillers on the thermal reflection and insulation performance of coating materials. The results showed that the surface modification effect of nano zinc oxide was the best when the silane coupling agent addition was 6%. The reflection and insulation performance of the coatings were the best when the additions of modified nano zinc oxide, hollow glass microspheres, and sepiolite nanofibers were 3%, 4%, and 4%, respectively. Compared with the control coating materials, the thermal insulation effect was improved obviously, which was evaluated by the -13.5 degrees C increase of maximum temperature difference between the upper and the lower surfaces. PMID:24734652
Wang, Fei; Liang, Jinsheng; Tang, Qingguo; Chen, Gong; Chen, Yalei
Performance characterization of fiber Bragg grating thermal response in space vacuum thermal environment
We investigated the fiber Bragg grating (FBG) thermal response in space vacuum thermal environment. The FBGs were packaged with 6061-T6 aluminum. The liquid nitrogen immersion experiment results show that its wavelength shift standard deviation is 0.76 pm for 217 h. The combination effect of vacuum and cryogenic temperature was studied by thermal cycling process in space environment simulator. The FBG sensors show accuracy better than 2% full scale, and the hysteresis errors are below 1%. It proves that these metal packaged FBG sensors can survive and meet the requirement of space measurement.
Jiang, Junfeng; Song, Luyao; Liu, Tiegen; Zhang, Jingchuan; Liu, Kun; Wang, Shuang; Yin, Jinde; Zhao, Peng; Xie, Jihui; Wu, Fan; Zhang, Xuezhi
Performance characterization of fiber Bragg grating thermal response in space vacuum thermal environment.
We investigated the fiber Bragg grating (FBG) thermal response in space vacuum thermal environment. The FBGs were packaged with 6061-T6 aluminum. The liquid nitrogen immersion experiment results show that its wavelength shift standard deviation is 0.76 pm for 217 h. The combination effect of vacuum and cryogenic temperature was studied by thermal cycling process in space environment simulator. The FBG sensors show accuracy better than 2% full scale, and the hysteresis errors are below 1%. It proves that these metal packaged FBG sensors can survive and meet the requirement of space measurement. PMID:24387420
Weathering of Roofing Materials-An Overview
An overview of several aspects of the weathering of roofing materials is presented. Degradation of materials initiated by ultraviolet radiation is discussed for plastics used in roofing, as well as wood and asphalt. Elevated temperatures accelerate many deleterious chemical reactions and hasten diffusion of material components. Effects of moisture include decay of wood, acceleration of corrosion of metals, staining of clay, and freeze-thaw damage. Soiling of roofing materials causes objectionable stains and reduces the solar reflectance of reflective materials. (Soiling of non-reflective materials can also increase solar reflectance.) Soiling can be attributed to biological growth (e.g., cyanobacteria, fungi, algae), deposits of organic and mineral particles, and to the accumulation of flyash, hydrocarbons and soot from combustion.
Berdahl, Paul; Akbari, Hashem; Levinson, Ronnen; Miller, William A.
Roofing as a source of nonpoint water pollution.
Sixteen wooden structures with two roofs each were installed to study runoff quality for four commonly used roofing materials (wood shingle, composition shingle, painted aluminum, and galvanized iron) at Nacogdoches, Texas. Each roof, either facing NW or SE, was 1.22 m wide x 3.66 m long with a 25.8% roof slope. Thus, there were 32 alternatively arranged roofs, consisting of four roof types x two aspects x four replicates, in the study. Runoff from the roofs was collected through galvanized gutters, downspouts, and splitters. The roof runoff was compared to rainwater collected by a wet/dry acid rain collector for the concentrations of eight water quality variables, i.e. Cu(2+), Mn(2+), Pb(2+), Zn(2+), Mg(2+), Al(3+), EC and pH. Based on 31 storms collected between October 1997 and December 1998, the results showed: (1) concentrations of pH, Cu, and Zn in rainwater already exceed the EPA freshwater quality standards even without pollutant inputs from roofs, (2) Zn and Cu, the two most serious pollutants in roof runoff, exceeded the EPA national freshwater water quality standards in virtually 100% and more than 60% of the samples, respectively, (3) pH, EC, and Zn were the only three variables significantly affected by roofing materials, (4) differences in Zn concentrations were significant among all roof types and between all roof runoff and rainwater samples, (5) although there were no differences in Cu concentrations among all roof types and between roof runoff and rainwater, all means and medians of runoff and rainwater exceeded the national water quality standards, (6) water quality from wood shingles was the worst among the roof types studied, and (7) although SE is the most frequent and NW the least frequent direction for incoming storms, only EC, Mg, Mn, and Zn in wood shingle runoff from the SE were significantly higher than those from the NW; the two aspects affected no other elements in runoff from the other three roof types. Also, Zn concentrations from new wood-shingle roofs were significantly higher than those from aged roofs of a previous study. The study demonstrated that roofs could be a serious source of nonpoint water pollution. Since Zn is the most serious water pollutant and wood shingle is the worst of the four roof types, using less compounds and materials associated with Zn along with good care and maintenance of roofs are critical in reducing Zn pollution in roof runoff. PMID:15531389
Chang, Mingteh; McBroom, Matthew W; Scott Beasley, R
Advanced Low Conductivity Thermal Barrier Coatings: Performance and Future Directions (Invited paper)
Piston Assembly Design for Improved Thermal-Tribological Performance
The tribological system in the piston assembly of an internal combustion engine includes contacts at interfaces of piston\\/piston ring\\/cylinder liner, piston skirt\\/cylinder wall, and piston\\/piston pin\\/ connecting rod. The thermal and tribological properties of the piston, piston rings, and cylinder wall are critical to the life and quality of the engine. Severe wear and scuffing failure, especially at the ring\\/ring
Qian Wang; Yiding Cao; Gang Chen
Room temperature soldering of microelectronic components for enhanced thermal performance
A novel fluxless soldering process is presented, that enables lead-free soldering of semiconductor die-to-heat spreader (and heat spreader-to-heat sink structures) at room temperature. The process is based on the use of reactive multilayer foils to locally melt the solder interface. Silicon-copper samples joined with indium solder are thermally characterized for a range of die sizes and bond line thicknesses. The
J. S. Subramanian; P. Rodgers; J. Newson; T. Rude; Z. He; E. Besnoin; T. P. Weihs; V. Eveloy; M. Pecht
High performance amorphous steel coating prepared by HVOF thermal spraying
Amorphous steel coating with a composition of Fe48Cr15Mo14C15B6Y2 was prepared by means of high velocity oxygen fuel (HVOF) thermal spraying. Microstructural analysis gives the information about porosity, oxidation and nanocrystal precipitation. Properties including the hardness, wear, corrosion and magnetic behaviors of the coating were examined. It was shown that the microhardness and wear resistance of the coating are superior to
H. S. Ni; X. H. Liu; X. C. Chang; W. L. Hou; W. Liu; J. Q. Wang
Thermal performance monitoring system for PWR nuclear power plants.
In order to improve heat rate and availability on its PWR nuclear power plants, Electricite de France is developing a performance monitoring system to evaluate operational performance variations, localize faulty components or systems and help maintenance ...
D. Brudy
Ballistic performance of porous-ceramic, thermal protection systems
Porous-ceramic, thermal protection systems are used heavily in current reentry vehicles like the Orbiter, and they are currently being proposed for the next generation of US manned spacecraft, Orion. These systems insulate reentry critical components of a spacecraft against the intense thermal environments of atmospheric reentry. Additionally, these materials are highly exposed to space environment hazards like solid particle impacts. This paper discusses impact studies up to 10 km/s on 8 lb/ft3 alumina-fiber-enhanced-thermal-barrier (AETB8) tiles coated with a toughened-unipiece-fibrousinsulation/ reaction-cured-glass layer (TUFI/RCG). A semi-empirical, first principles impact model that describes projectile dispersion is described that provides excellent agreement with observations over a broad range of impact velocities, obliquities and projectile materials. Model extensions to look at the implications of greater than 10 GPa equation of state is also discussed. Predicted penetration probabilities for a vehicle visiting the International Space Station is 60% lower for orbital debris and 95% lower for meteoroids with this model compared to an energy scaled approach.
Miller, Joshua E.; Bohl, William E.; Christiansen, Eric C.; Davis, Bruce A.; Foreman, Cory D.
Ballistic Performance of Porous-Ceramic, Thermal Protection Systems
Porous-ceramic, thermal protection systems are used heavily in current reentry vehicles like the Orbiter, and they are currently being proposed for the next generation of US manned spacecraft, Orion. These systems insulate reentry critical components of a spacecraft against the intense thermal environments of atmospheric reentry. Additionally, these materials are also highly exposed to space environment hazards like solid particle impacts. This paper discusses impact testing up to 9.65 km/s on one of these systems. The materials considered are 8 lb/ft^3 alumina-fiber-enhanced-thermal-barrier (AETB8) tiles coated with a toughened-unipiece-fibrous-insulation/reaction-cured-glass layer (TUFI/RCG). A semi-empirical, first principals impact model that describes projectile dispersion is described that provides excellent agreement with observations over a broad range of impact velocities, obliquities and projectile materials. A model extension to look at the implications of greater than 10 GPa equation of state measurements is also discussed. Predicted penetration probabilities for a vehicle visiting the International Space Station is 60% lower for orbital debris and 95% lower for meteoroids with this model compared to an energy scaled approach.
Miller, Joshua; Bohl, William; Christiansen, Eric; Davis, B. Alan; Foreman, Cory
Flightweight radiantly and actively cooled panel: Thermal and structural performance
A 2- by 4-ft flightweight panel was subjected to thermal/structural tests representative of design flight conditions for a Mach 6.7 transport and to off-design conditions simulating flight maneuvers and cooling system failures. The panel utilized Rene 41 heat shields backed by a thin layer of insulation to radiate away most of the 12 Btu/ft2-sec incident heating. A solution of ethylene glycol in water circulating through tubes in an aluminum-honeycomb-sandwich panel absorbed the remainder of the incident heating (0.8 Btu/sq ft-sec). The panel successfully withstood (1) 46.7 hr of radiant heating which included 53 thermal cycles and 5000 cycles of uniaxial inplane loading of + or - 1200 lfb/in; (2) simulated 2g-maneuver heating conditions and simulated cooling system failures without excessive temperatures on the structural panel; and (3) the extensive thermal/structural tests and the aerothermal tests reported in NASA TP-1595 without significant damage to the structural panel, coolant leaks, or hot-gas ingress to the structural panel.
Shore, C. P.; Nowak, R. J.; Kelly, H. N.
Porous-ceramic, thermal protection systems are used heavily in current reentry vehicles like the Orbiter, and they are currently being proposed for the next generation of US manned spacecraft, Orion. These systems insulate reentry critical components of a spacecraft against the intense thermal environments of atmospheric reentry. Additionally, these materials are highly exposed to space environment hazards like solid particle impacts. This paper discusses impact studies up to 10 km/s on 8 lb/cu ft alumina-fiber-enhanced-thermal-barrier (AETB8) tiles coated with a toughened-unipiece-fibrous-insulation/ reaction-cured-glass layer (TUFI/RCG). A semi-empirical, first principals impact model that describes projectile dispersion is described that provides excellent agreement with observations over a broad range of impact velocities, obliquities and projectile materials. Model extensions to look at the implications of greater than 10 GPa equation of state is also discussed. Predicted penetration probabilities for a vehicle visiting the International Space Station is 60% lower for orbital debris and 95% lower for meteoroids with this model compared to an energy scaled approach.
Miller, J. E.; Bohl, W. E.; Christiansen, Eric C.; Davis, B. A.; Foreman, C. D.
62 FR 8906 - Federal Motor Vehicle Safety Standards; Roof Crush Resistance
Federal Register 2010, 2011, 2012, 2013
...220 test procedure for roof crush resistance of raised roof vehicles. Standard No...resulting in diminished roof crush resistance, the agency does not agree that the...windshield probably contributes to roof crush resistance in more representative, less...
Health Hazard Evaluation/Toxicity Determination Report 75-194-324, Western Roofing Company, Sellers and Marquis Roofing Company, A. J. Shirk Roofing Company, Quality Roofing Company, Kansas City, Missouri.
The results of a medical-environmental evaluation indicates that employees were exposed to toxic concentrations of particulate polycyclic organic matter during roofing operations involving the tear-off of a 7 acre roof. The particulate polycyclic organic ...
R. L. Hervin E. A. Emmett
Thermoplastic Single-Ply Roof Relieves Water Damage and Inconvenience.
Assesses use of thermoplastic single-ply roofs by North Carolina's Mars Hill College to prevent leaks, reduce maintenance costs, and enhance the value of their older historic buildings. Administrators comment on the roof's installation efficiency and cleanliness. (GR)
Williams, Jennifer Lynn
Interior view of the Sheet Metal Shop showing the roof ...
Interior view of the Sheet Metal Shop showing the roof trusses and corrugated metal roof covering, view facing northwest - Kahului Cannery, Plant No. 28, Boiler House, Sheet Metal and Electrical Shops, 120 Kane Street, Kahului, Maui County, HI
Roofs That Last...And Last...And Last.
Describes the benefits of using protected membrane roofing (PMR) systems as a means of cutting maintenance and repair costs over the roof's lifetime. Addresses responses to arguments against using PMR systems. (GR)
Fickes, Michael
30 CFR 75.206 - Conventional roof support.
...ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Roof Support § 75.206 Conventional...mines using non-mechanized mining systems, when conventional roof support...
DETAIL VIEW ABOVE MAIN ASSEMBLY LEVEL SHOWING STEEL ROOF TRUSSES, ROOF MONITOR AND CATWALK AT COLUMN LINE U-28. - Offutt Air Force Base, Glenn L. Martin-Nebraska Bomber Plant, Building D, Peacekeeper Drive, Bellevue, Sarpy County, NE
18. Detail view of roof structure above the porte cochere, ...
18. Detail view of roof structure above the porte cochere, showing hipped roof construction, wooden beams and their intersection with columns - Bend Railroad Depot, 1160 Northeast Divion Street (At foot of Kearny Street), Bend, Deschutes County, OR
The Map to Cost-Effective Summer Roofing.
Roofing is one of the major expense items in school district maintenance budgets. Outlines steps to take in project planning, developing budget estimates and specifications, and completing a roofing project on time. (MLF)
Analysis of Wind Forces on Roof-Top Solar Panel
Structural loads on solar panels include forces due to high wind, gravity, thermal expansion, and earthquakes. International Building Code (IBC) and the American Society of Civil Engineers are two commonly used approaches in solar industries to address wind loads. Minimum Design Loads for Buildings and Other Structures (ASCE 7-02) can be used to calculate wind uplift loads on roof-mounted solar panels. The present study is primarily focused on 2D and 3D modeling with steady, and turbulent flow over an inclined solar panel on the flat based roof to predict the wind forces for designing wind management system. For the numerical simulation, 3-D incompressible flow with the standard k-? was adopted and commercial CFD software ANSYS FLUENT was used. Results were then validated with wind tunnel experiments with a good agreement. Solar panels with various aspect ratios for various high wind speeds and angle of attacks were modeled and simulated in order to predict the wind loads in various scenarios. The present study concluded to reduce the strong wind uplift by designing a guide plate or a deflector before the panel.
Panta, Yogendra; Kudav, Ganesh
Analytical Model for Computing Thermal Bridge Effects in High Performance Building Panels
SUMMARY: Vacuum insulation panels (VIPs) have recently been discovered by the building sector. Because they are evacuated, their ideal or centre-of-panel thermal conductivity is as low as about 0.004 W�m-1�K-1. As a consequence, vacuum insulation panels combine high thermal performance with limited construction thickness. Integrated into building panels, however, a thermal bridge effect occurs at the panel's edge due to
Martin J. Tenpierik; Wim H. van der Spoel; Johannes J. M. Cauberg
Automatic Roof Plane Detection and Analysis in Airborne Lidar Point Clouds for Solar Potential Assessment
A relative height threshold is defined to separate potential roof points from the point cloud, followed by a segmentation of these points into homogeneous areas fulfilling the defined constraints of roof planes. The normal vector of each laser point is an excellent feature to decompose the point cloud into segments describing planar patches. An object-based error assessment is performed to determine the accuracy of the presented classification. It results in 94.4% completeness and 88.4% correctness. Once all roof planes are detected in the 3D point cloud, solar potential analysis is performed for each point. Shadowing effects of nearby objects are taken into account by calculating the horizon of each point within the point cloud. Effects of cloud cover are also considered by using data from a nearby meteorological station. As a result the annual sum of the direct and diffuse radiation for each roof plane is derived. The presented method uses the full 3D information for both feature extraction and solar potential analysis, which offers a number of new applications in fields where natural processes are influenced by the incoming solar radiation (e.g., evapotranspiration, distribution of permafrost). The presented method detected fully automatically a subset of 809 out of 1,071 roof planes where the arithmetic mean of the annual incoming solar radiation is more than 700 kWh/m2.
Jochem, Andreas; Hofle, Bernhard; Rutzinger, Martin; Pfeifer, Norbert
A Portable Oxygen Subsystem - Description and preliminary thermal performance prediction
This paper describes the use, operation, and preliminary thermal modeling of a Portable Oxygen Subsystem (POS). The POS is a partial rebreather which is being developed for Shuttle Orbiter support. Normally used as a pre-breather for denitrogenization prior to EVA, this semi-closed, breath powered breathing system can also be used for emergencies in the event of a contaminated or oxygen-deficient cabin atmosphere, to support an emergency transfer between vehicles, or as a clean oxygen supply in the event of a contaminated ambient atmosphere in the vicinity of the Orbiter after landing.
Sribnik, F.
The GOES Imager and Sounder Radiant Coolers are controlled to run at temperatures around 100 K. Future instruments may have added detectors and additional detector heat that will cause the radiant cooler temperatures to rise if design changes are not implemented. Thermal analyses show that lowering the radiant energy from the cooler sun shield (temperatures range between 170 K and 250 K) and/or the Solar Sail Astromast (temperatures range between 270 K and 310 K) adsorbed by the 100 K cooler patch (detector radiator) can significantly lower cooler temperatures if the patch hemispherical emittance is not lowered substantially. The existing cooler patch is an open honeycomb with black paint (Z-307) and had an extremely high emittance even at 100 K. The proposed approach is to replace the open honeycomb with a coating that is spectrally selective with low absorptance out to 10 micrometers and high absorptance beyond 20 micrometers. Several coating formulations were developed and parametric thermal analyses were conducted to select the coating formulation for final coating verification. The coating formulation selected was Ag/Al2O3 (14,000 �)/TiO2 (6,000 �)/Al2O3 (14,000 �) vacuum deposited to a highly specular substrate. The thermal radiative properties were: solar absorptance, 0.09, hemispherical emittance at 100 K, 0.80, IR absorptance (200 K blackbody), 0.78, and IR absorptance (300 K BB), 0.65. To take advantage of the low solar absorptance of this cooler patch coating, a change in the Astromast coating was proposed that would keep its solar absorptance/emittance ratio the same (approximately 1.0), but significantly lower the emittance, and thereby lower the IR irradiance on the emitter. The net results reduce the patch temperature by approximately 9 K. The paper will also contain descriptions of the environmental tests and measurements conducted on the coatings and the results of the thermal parametric studies on the cooler patch.
Neuberger, Dave; Ackerman, Norm; Harris, George
Process of making cryogenically cooled high thermal performance crystal optics
A method for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N.sub.2 is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation.
Kuzay, Tuncer M. (Naperville, IL)
A method is disclosed for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N[sub 2] is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation. 7 figs.
Kuzay, T.M.
This presentation provides an overview of electromagnetic heating technology that has proven useful in clinical applications of hyperthermia therapy for cancer. Several RF and microwave antenna designs are illustrated which highlight the evolution of technology from simple waveguide antennas to spatially and temporally adjustable multiple antenna phased arrays for deep heating, conformal arrays for superficial heating, and compatible approaches for radiometric and magnetic resonance image based non-invasive thermal monitoring. Examples of heating capabilities for several recently developed applicators demonstrate highly adjustable power deposition that has not been possible in the past.
Stauffer, P.R.; Maccarini, P.F.
40 CFR 63.902 - Standards-Tank fixed roof.
...2013-07-01 false Standards-Tank fixed roof. 63.902 Section 63.902 ...Tanks-Level 1 § 63.902 Standards�Tank fixed roof. (a) This section applies...controlling air emissions from a tank using a fixed roof. This section does not apply to...
40 CFR 63.1043 - Standards-Separator floating roof.
...2009-07-01 false Standards-Separator floating roof. 63.1043 Section 63.1043... § 63.1043 Standards�Separator floating roof. (a) This section applies...separator or organic-water separator using a floating roof. (b) The separator shall...
40 CFR 63.1063 - Floating roof requirements.
...2010-07-01 2010-07-01 false Floating roof requirements. 63.1063 Section...Control Level 2 § 63.1063 Floating roof requirements. The owner or operator who elects to use a floating roof to comply with the...
...2013-07-01 2013-07-01 false Floating roof requirements. 63.1063 Section...Control Level 2 § 63.1063 Floating roof requirements. The owner or operator who elects to use a floating roof to comply with the...
40 CFR 65.44 - External floating roof (EFR).
...2013-07-01 2013-07-01 false External floating roof (EFR). 65.44 Section 65...Storage Vessels § 65.44 External floating roof (EFR). (a) EFR design requirements...material emissions by using an external floating roof shall comply with the design...
...2009-07-01 2009-07-01 false External floating roof (EFR). 65.44 Section 65...Storage Vessels § 65.44 External floating roof (EFR). (a) EFR design requirements...material emissions by using an external floating roof shall comply with the design...
...2010-07-01 2010-07-01 false External floating roof (EFR). 65.44 Section 65...Storage Vessels § 65.44 External floating roof (EFR). (a) EFR design requirements...material emissions by using an external floating roof shall comply with the design...
...2013-07-01 false Standards-Separator floating roof. 63.1043 Section 63.1043... § 63.1043 Standards�Separator floating roof. (a) This section applies...separator or organic-water separator using a floating roof. (b) The separator shall...
...2010-07-01 false Standards-Separator floating roof. 63.1043 Section 63.1043... § 63.1043 Standards�Separator floating roof. (a) This section applies...separator or organic-water separator using a floating roof. (b) The separator shall...
...2009-07-01 2009-07-01 false Floating roof requirements. 63.1063 Section...Control Level 2 § 63.1063 Floating roof requirements. The owner or operator who elects to use a floating roof to comply with the...
Which Roof is Tops? Grades PreK-2.
This introductory activity explores the advantages of different roof shapes for different climates or situations. It addresses questions such as "When you walk or drive around your neighborhood, what do the roofs look like?" and "What if you lived in an area with a different climate, how would that affect the style of roof that you might find?"�
Rushton, Erik; Ryan, Emily; Swift, Charles
Mine roof driller-bolter apparatus and method
An apparatus for bolting the roof of an underground mine is disclosed comprising a mobile frame, a boom extending from the frame and a housing provided at the end of the frame. The housing supports an upwardly extending stinger, a drilling mechanism including a drill centralizer having a central bore therethrough and a passageway in communication with the central bore, a device for delivering a container of roof bolting anchoring media through the passageway and through the drill centralizer and into a drilled hole, a device for indexing a roof bolt into alignment with the drilled hole and a spinner for driving the roof bolt into the drilled hole. The present invention also provides a method for bolting the roof of an underground mine comprising the steps of stinging a housing against the roof of the mine, moving a drill centralizer into communication with the roof and drilling a hole in the roof. Without retracting the drill centralizer from communication with the roof, a container of roof bolt anchoring media is delivered through the centralizer and into the drilled hole. The drill centralizer is thereafter retracted and the housing is moved to align a roof bolt with a drilled hole. Then the roof bolt is driven into the drilled hole and the bolt anchoring media sets around the bolt.
Hibbard, G.A.; Lumbra, R.C.; Morrison, W.D.
Machine Modification for Roof Bolt Placement in Low Coal.
A roof bolt bender/inserter was designed and built to install roof bolts in low coal mines where the bolts used are longer than the seam height. The bender/inserter was installed on a Fletcher LTDO roof drill and evaluated in Clinchfield Mine Moss No. 2, ...
W. Hermanson W. Rowe R. Sloan
Recovery and reuse of asphalt roofing waste. Final report
Burning of asphalt roofing waste as a fuel and incorporating asphalt roofing waste in bituminous paving were identified as the two outstanding resource recovery concepts out of ten studied. Four additional concepts might be worth considering under different market or technical circumstances. Another four concepts were rated as worth no further consideration at this time. This study of the recovery of the resource represented in asphalt roofing waste has identified the sources and quantities of roofing waste. About six million cubic yards of scrap roofing are generated annually in the United States, about 94% from removal of old roofing at the job site and the remainder from roofing material production at factories. Waste disposal is a growing problem for manufacturers and contractors. Nearly all roofing waste is hauled to landfills at a considerable expense to roofing contractors and manufacturers. Recovery of the roofing waste resource should require only a modest economic incentive. The asphalt contained in roofing waste represents an energy resource of more than 7 x 10/sup 13/ Btu/year. Another 1 x 10/sup 13/ Btu/year may be contained in field-applied asphalt on commercial building roofs. The two concepts recommended by this study appear to offer the broadest applicability, the most favorable economics, and the highest potential for near-term implementation to reuse this resource.
Desai, S.; Graziano, G.; Shepherd, P.
Roofing with Urethane: Pro and Con.
Gerald Scott's favorable evaluation of the foamed polyurethane roofing system is based on experiences with 55 buildings at Texas A & M. Michael Kinzer, an architect at Colorado State University, disagrees and claims that the system is difficult to install and maintain, and the cost prohibitive. (MLF)
Kinzer, Michael; Scott, Gerald P.E.
Thrust bolting: roof bolt support apparatus
A method of installing a tensioned roof bolt in a borehole of a rock formation without the aid of a mechanical anchoring device or threaded tensioning threads by applying thrust to the bolt (19) as the bonding material (7') is curing to compress the strata (3) surrounding the borehole (1), and then relieving the thrust when the bonding material (7') has cured.
Tadolini, Stephen C. (Lakewood, CO); Dolinar, Dennis R. (Golden, CO)
Waffle Shells for Roof and Floor.
This report describes the design and construction of the waffle shell system used for roofs and floors. It is based on the funicular shell, which was evolved as a structural element deriving its strength through shape. It develops a state of pure compress...
G. George N. Sethuraman
Pluralism and Prayer under One Roof.
Reports on increasing efforts by colleges and universities to meet the spiritual needs of minority students by providing religious centers where students of all faiths can worship under one roof. Examples include the Massachusetts Institute of Technology, Mount Holyoke College (Massachusetts), and Johns Hopkins University (Maryland). (DB)
McMurtrie, Beth
Suspended roof construction for industrial furnaces
A refractory brick panel module and suspended roof construction for high temperature furnaces wherein the panel module has a refractory support frame of at least two substantially parallel support members with at least one end of the support members having extension and retraction means forming an extendable and retractable refractory support frame end portion. The refractory support frame end portion
Construction of Experimental Polyvinyl Chloride (PVC) Roofing.
Polyvinyl chloride (PVC) singly-ply roofing systems have been installed at three U.S. military facilities for long-term evaluation (10 years) in three environments. Commercial PVC systems previously had been shown to offer an alternative to conventional b...
M. J. Rosenfield
Roof Shield for Advance and Retreat Mining
Shield sections change their configuration to suit mining mode. Articulation cylinders raise rear shield to advance position, and locking cylinders hold it there. To change to retreat position articulation cylinders lower shield. Locking pins at edge of outermost shield plate latch shield to chock base. Shield accommodates roof heights ranging from 36 to 60 inches (0.9 to 1.52 meters).
Lewis, E. V.
Chemical kinetic performance losses for a hydrogen laser thermal thruster
Projected requirements for efficient, economical, orbit-raising propulsion systems have generated investigations into several potentially high specific impulse, moderate thrust, advanced systems. One of these systems, laser thermal propulsion, utilizes a high temperature plasma as the enthalpy source. The plasma is sustained by a focused laser beam which maintains the plasma temperature at levels near 20,000 K. Since such temperature levels lead to total dissociation and high ionization, the plasma thruster system potentially has a high specific impulse decrement due to recombination losses. The nozzle flow is expected to be sufficiently nonequilibrium to warrant concern over the achievable specific impluse. This investigation was an attempt at evaluation of those losses. The One-Dimensional Kinetics (ODK) option of the Two-Dimensional Kinetics (TDK) Computer Program was used with a chemical kinetics rate set obtained from available literature to determine the chemical kinetic energy losses for typical plasma thruster conditions. The rates were varied about the nominal accepted values to band the possible losses. Kinetic losses were shown to be highly significant for a laser thermal thruster using hydrogen. A 30 percent reduction in specific impulse is possible simply due to the inability to completely extract the molecular recombination energy.
Mccay, T. D.; Dexter, C. E.
Thermal Performance of Orion Active Thermal Control System With Seven-Panel Reduced-Curvature Radiator.
The active thermal control system (ATCS) of the crew exploration vehicle (Orion) uses radiator panels with fluid loops as the primary system to reject heat from spacecraft. The Lockheed Martin (LM) baseline Orion ATCS uses eight-panel radiator coated with...
J. R. Yuko X. Y. J. Wang
Experimental measurement and simulation of thermal performance due to aging in power semiconductor devices
Power cycling in operating power semiconductors creates stresses in the device package. These stresses cause cracks to grow in the solder die-attach layer, leading to voids between the silicon and the heat spreader. The thermal performance of power semiconductor devices is eventually compromised by these voids. This study compares the thermal impedance of modules with varying void area at a
D. C. Katsis; J. D. van Wyk
Winter indoor air quality, thermal comfort and acoustic performance of newly built secondary schools in England
Previous studies have found that classrooms are often inadequately ventilated, with the resultant increased risk of negative impacts on the pupils. This paper describes a series of field measurements that investigated the indoor air quality, thermal comfort and acoustic performance of nine recently built secondary schools in England. The most significant conclusion is that the complex interaction between ventilation, thermal
D. Mumovic; J. Palmer; M. Davies; M. Orme; I. Ridley; T. Oreszczyn; C. Judd; R. Critchlow; H. A. Medina; G. Pilmoor; C. Pearson
An experimental investigation of the thermal performance of an asymmetrical flat plate heat pipe
An experimental investigation of the thermal performance of a flat plate heat pipe is presented in this work. The results indicate that the temperature along the heat pipe wall surfaces is quite uniform. The results also indicate that the porous wick of the evaporator section creates the main thermal resistance resulting in the largest temperature drop, which consequently affects the
Y. Wang; K. Vafai
Design and calibration of a test facility for MLI thermal performance measurements below 80K.
The design geometry of the SSC dipole cryostat includes active thermal radiation shields operating at 80K and 20K respectively. Extensive measurements conducted in a Heat Leak Test Facility (HLTF) have been used to evaluate the thermal performance of cand...
W. Boroski R. Kunzelman M. Ruschman C. Schoo
Thermal performance evaluation of precast concrete three-wythe sandwich wall panels
Precast concrete sandwich wall panels are commonly constructed of two wythes of concrete separated by a layer of thermal insulation. In these two-wythe panels, solid concrete regions are often provided for embedded hardware for lifting, handling, and connections, or to provide composite action. These solid concrete regions can have a significant adverse impact on the thermal performance of the panels.
Byoung-Jun Lee; Stephen Pessiki
Effects of shield on thermal-fluid performance of vapor chamber heat sink
This work investigates the effects of a shield on the thermal and hydraulic characteristics of plate-fin vapor chamber heat sinks under cross flow cooling. The surface temperature distributions of the vapor chamber heat sinks are measured using infrared thermography. The thermal-fluid performance of vapor chamber heat sinks with a shield is determined by varying the fin width, the fin height,
Hung-Yi Li; Ming-Hung Chiang
Thermal performance measurement of heat sinks with confined impinging jet by infrared thermography
In this paper, the thermal performance of heat sinks with confined impingement cooling is measured by infrared thermography. The effects of the impinging Reynolds number, the width and the height of the fins, the distance between the nozzle and the tip of the fins, and the type of the heat sinks on the thermal resistance are investigated. The results show
Hung-Yi Li; Shung-Ming Chao; Go-Long Tsai
Electrical insulation performance under thermal and electrical combined stress for resistive fault current limiters
This paper discusses the electrical insulation performance of resistive superconducting fault current limiters (SFCL) under quench condition exposed to thermal and electrical combined stress. Electrical stress of 50 Hz AC was applied to parallel ring electrodes molded with epoxy resin. Thermal stress simulating the quench of the resistive SFCL was simultaneously applied to the ring electrode by an electromagnetic induction
N. Hayakawa; M. Noe; K.-P. Juengst; H. Okubo
Variation in thermal performance and reaction norms among populations of Drosophila melanogaster.
The major goal of evolutionary thermal biology is to understand how variation in temperature shapes phenotypic evolution. Comparing thermal reaction norms among populations from different thermal environments allows us to gain insights into the evolutionary mechanisms underlying thermal adaptation. Here, we have examined thermal adaptation in six wild populations of the fruit fly (Drosophila melanogaster) from markedly different natural environments by analyzing thermal reaction norms for fecundity, thorax length, wing area, and ovariole number under ecologically realistic fluctuating temperature regimes in the laboratory. Contrary to expectation, we found only minor differences in the thermal optima for fecundity among populations. Differentiation among populations was mainly due to differences in absolute (and partly also relative) thermal fecundity performance. Despite significant variation among populations in the absolute values of morphological traits, we observed only minor differentiation in their reaction norms. Overall, the thermal reaction norms for all traits examined were remarkably similar among different populations. Our results therefore suggest that thermal adaptation in D. melanogaster predominantly involves evolutionary changes in absolute trait values rather than in aspects of thermal reaction norms. PMID:24299409
Klepsatel, Peter; G�likov�, Martina; De Maio, Nicola; Huber, Christian D; Schl�tterer, Christian; Flatt, Thomas
High temperature performance of flexible thermal protection materials
Aero convective tests of several flexible thermal protection system (FTPS) concepts were conducted in the NASA Ames Research Center 20 MW arcjet aero heating wind tunnel. The concepts consisted of quilted insulation blankets with nextel AB312 felt insulation stitched between cover cloths with AB312 thread. The cover cloths were commercially available nextel AB312 and nicalon fabrics. The specimens were subjected to convective heat fluxes ranging from 7 to 35 Btu/per sq ft per sec at stagnation pressures of .005 to .02 atm. Specimens were tested both with and without transpiration cooling. Results indicated that both the nextel and nicalon fabrics offer the potential for higher temperature applications than current FTPS, and nicalon appears to be capable of withstanding temperatures well above 2500 degrees F with minimal degradation.
Savage, R. T.; Love, W.; Bloetscher, F.
Thermal performance of a proposed evacuated multi-layer insulation system for the National Aerospace Plane
The National Aerospace Plane (NASP) will require thermal insulation systems which are consistent with cryogenic fluids, high thermal loads, and design restrictions such as weight and volume. Test sections of the proposed system have been constructed and evaluated. In this paper we discuss the components of the insulation system, the application of the insulation system to the NASP liquid hydrogen fuel tank system, and thermal conductivity measurements performed on test sections of the system. Both steady-state and transient thermal measurements are presented.
Dube, W. P.; Slifka, A. J.; Jeffs, R. L.
Hypothetical Reentry Thermostructural Performance of Space Shuttle Orbiter With Missing or Eroded Thermal Protection Tiles.
This report deals with hypothetical reentry thermostructural performance of the Space Shuttle orbiter with missing or eroded thermal protection system (TPS) tiles. The original STS-5 heating (normal transition at 1100 sec) and the modified STS-5 heating (...
W. L. Ko L. Gong R. D. Quinn
Skylab Experiment Performance Evaluation Manual. Appendix B Experiment M-415, Thermal Control Coatings (Msfc).
Performance tests to determine the thermodynamic properties of thermal control coatings for application to the Skylab corollary experiments under preflight, inflight, and postflight conditions are described. Malfunction analyses and procedures for working...
K. S. Purushotham
Status of cool roof standards in the United States
Since 1999, several widely used building energy efficiency standards, including ASHRAE 90.1, ASHRAE 90.2, the International Energy Conservation Code, and California's Title 24 have adopted cool roof credits or requirements. We review the technical development of cool roof provisions in the ASHRAE 90.1, ASHRAE 90.2, and California Title 24 standards, and discuss the treatment of cool roofs in other standards and energy-efficiency programs. The techniques used to develop the ASHRAE and Title 24 cool roof provisions can be used as models to address cool roofs in building energy standards worldwide.
Akbari, Hashem; Levinson, Ronnen
Indoor test for thermal performance of the Sunmaster evacuated tube (liquid) solar collector
The test procedures used to obtain the thermal performance data for a solar collector under simulated conditions are presented. Tests included a stagnation test, a time constant test, a thermal efficiency test, an incident angle modifier test, and a hot fill test. All tests were performed at ambient conditions and the transient effect and the incident angle effect on the collector were determined. The solar collector is a water working fluid type.
The growth and survival of plants in urban green roofs in a dry climate.
Green roofs as one of the components of water-sensitive urban design have become widely used in recent years. This paper describes performance monitoring of four prototype-scale experimental green roofs in a northern suburb of Adelaide, South Australia, undertaken over a 1-year period. Four species of indigenous Australian ground cover and grass species comprising Carpobrotus rossii, Lomandra longifolia 'Tanika,' Dianella caerula 'Breeze' and Myoporum parvifolium were planted in extensive and intensive green roof configurations using two different growing media. The first medium consisted of crushed brick, scoria, coir fibre and composted organics while the second comprised scoria, composted pine bark and hydro-cell flakes. Plant growth indices including vertical and horizontal growth rate, leaf succulence, shoot and root biomasses, water use efficiency and irrigation regimes were studied during a 12-month period. The results showed that the succulent species, C. rossii, can best tolerate the hot, dry summer conditions of South Australia, and this species showed a 100% survival rate and had the maximum horizontal growth rate, leaf succulence, shoot biomass and water use efficiency. All of the plants in the intensive green roofs with the crushed brick mix media survived during the term of this study. It was shown that stormwater can be used as a source of irrigation water for green roofs during 8 months of the year in Adelaide. However, supplementary irrigation is required for some of the plants over a full annual cycle. PMID:24468503
Razzaghmanesh, M; Beecham, S; Kazemi, F
Effects of aerodynamic heating and TPS thermal performance uncertainties on the Shuttle Orbiter
A procedure for estimating uncertainties in the aerodynamic-heating and thermal protection system (TPS) thermal-performance methodologies developed for the Shuttle Orbiter is presented. This procedure is used in predicting uncertainty bands around expected or nominal TPS thermal responses for the Orbiter during entry. Individual flowfield and TPS parameters that make major contributions to these uncertainty bands are identified and, by statistical considerations, combined in a manner suitable for making engineering estimates of the TPS thermal confidence intervals and temperature margins relative to design limits. Thus, for a fixed TPS design, entry trajectories for future Orbiter missions can be shaped subject to both the thermal-margin and confidence-interval requirements. This procedure is illustrated by assessing the thermal margins offered by selected areas of the existing Orbiter TPS design for an entry trajectory typifying early flight test missions.
Goodrich, W. D.; Derry, S. M.; Maraia, R. J.
Topex Microwave Radiometer thermal control - Post-system-test modifications and on-orbit performance
The Topex Microwave Radiometer has had an excellent thermal performance since launch. The instrument, however, went through a hardware modification right before launch to correct for a thermal design inadequacy that was uncovered during the spacecraft thermal vacuum test. This paper reports on how the initially obscure problem was tracked down, and how the thermal models were revised, validated, and utilized to investigate the solution options and guide the hardware modification decisions. Details related to test data interpretation, analytical uncertainties, and model-prediction vs. test-data correlation, are documented. Instrument/spacecraft interface issues, where the problem originated and where in general pitfalls abound, are dealt with specifically. Finally, on-orbit thermal performance data are presented, which exhibit good agreement with flight predictions, and lessons learned are discussed.
Lin, Edward I.
The Effect of Cooling Methods on the Performance of Solid Nitrogen Thermal Batteries
A test cryostat has been constructed to study thermal batteries. Solid nitrogen, used as a thermal battery, may be used as a temporary portable cooling system or a heat absorber for a superconducting fault current limiter system. The nitrogen was solidified via different cooling profiles. The performance of thermal batteries was determined by subjecting them to transient thermal events. It was found that slowly formed solid nitrogen performed best, by returning to operating temperature faster. The thermal contact degradation due to �dry-out� was identified as a significant problem after a number of successive pulses when using rapidly formed solid nitrogen, yet did not present itself in slowly formed solid nitrogen, within experimental range.
Jarvis, A. L. L.; Swann, B. M.; Archer, J. C.
A low pressure nuclear thermal propulsion (LPNTP) system, which takes advantage of hydrogen dissociation/recombination, was proposed as a means of increasing engine specific impulse (Isp). The effect of hydrogen dissociation/recombination on LPNTP Isp is examined. A two-dimensional computer model was used to show that the optimum chamber pressure is approximately 100 psia (at a chamber temperature of 3,000 K), with an Isp approximately 15 s higher than at 1,000 psia. At high chamber temperatures and low chamber pressures, the increase in Isp is due to both lower average molecular weights caused by dissociation and added kinetic energy from monatomic hydrogen recombination. Monatomic hydrogen recombination increases the Isp more then hydrogen dissociation. Variations in the mole fraction of monatomic hydrogen are similar to variations in static pressure along the axial nozzle position. Most recombination occurs close to the nozzle throat. Practical variations in nozzle geometry have minimal impact on recombination. Other models which can simulate a wider range of nozzle designs should be used in the future. The uncertainty of the hydrogen kinetic reaction rates at high temperatures (approximately 3,000 K) affects the accuracy of the analysis and should be verified with simple bench tests.
Gerrish, H. P., Jr.; Doughty, G. E.
Thermal barrier coatings were exposed to the high temperature and high heat flux produced by a 30 kW plasma torch. Analysis of the specimen heating rates indicates that the temperature drop across the thickness of the 0.038 cm ceramic layer was about 1100 C after 0.5 sec in the flame. An as-sprayed ZrO2-8%Y2O3 specimens survived 3000 of the 0.5 sec cycles with failing. Surface spalling was observed when 2.5 sec cycles were employed but this was attributed to uneven heating caused by surface roughness. This surface spalling was prevented by smoothing the surface with silicon carbide paper or by laser glazing. A coated specimen with no surface modification but which was heat treated in argon also did not surface spall. Heat treatment in air led to spalling in as early as 2 cycle from heating stresses. Failures at edges were investigated and shown to be a minor source of concern. Ceramic coatings formed from ZrO2-12%Y2O3 or ZrO2-20%Y2O3 were shown to be unsuited for use under the high heat flux conditions of this study.
Miller, R. A.; Berndt, C. C.
Planck early results. II. The thermal performance of Planck
The performance of the Planck instruments in space is enabled by their low operating temperatures, 20 K for LFI and 0.1 K for HFI, achieved through a combination of passive radiative cooling and three active mechanical coolers. The scientific requirement for very broad frequency coverage led to two detector technologies with widely different temperature and cooling needs. Active coolers could
P. A. R. Ade; N. Aghanim; M. Arnaud; M. Ashdown; J. Aumont; C. Baccigalupi; M. Baker; A. Balbi; A. J. Banday; R. B. Barreiro; E. Battaner; K. Benabed; A. Beno�t; J.-P. Bernard; M. Bersanelli; P. Bhandari; R. Bhatia; J. J. Bock; A. Bonaldi; J. R. Bond; J. Borders; J. Borrill; B. Bowman; T. Bradshaw; E. Br�elle; M. Bucher; C. Burigana; R. C. Butler; P. Cabella; C. M. Cantalupo; B. Cappellini; J.-F. Cardoso; A. Catalano; L. Cay�n; A. Challinor; A. Chamballu; J. P. Chambelland; J. Charra; M. Charra; L.-Y. Chiang; C. Chiang; P. R. Christensen; D. L. Clements; B. Collaudin; S. Colombi; F. Couchot; A. Coulais; B. P. Crill; M. Crook; F. Cuttaia; C. Damasio; L. Danese; R. D. Davies; R. J. Davis; P. de Bernardis; G. de Gasperis; A. de Rosa; J. Delabrouille; J.-M. Delouis; F.-X. D�sert; K. Dolag; S. Donzelli; O. Dor�; U. D�rl; M. Douspis; X. Dupac; G. Efstathiou; T. A. En�lin; H. K. Eriksen; C. Filliard; F. Finelli; S. Foley; O. Forni; P. Fosalba; J.-J. Fourmond; M. Frailis; E. Franceschi; S. Galeotta; K. Ganga; E. Gavila; M. Giard; G. Giardino; Y. Giraud-H�raud; J. Gonz�lez-Nuevo; K. M. G�rski; S. Gratton; A. Gregorio; A. Gruppuso; G. Guyot; D. Harrison; G. Helou; S. Henrot-Versill�; C. Hern�ndez-Monteagudo; D. Herranz; S. R. Hildebrandt; E. Hivon; M. Hobson; A. Hornstrup; W. Hovest; R. J. Hoyland; K. M. Huffenberger; U. Israelsson; A. H. Jaffe; W. C. Jones; M. Juvela; E. Keih�nen; R. Keskitalo; T. S. Kisner; R. Kneissl; L. Knox; H. Kurki-Suonio; G. Lagache; J.-M. Lamarre; P. Lami; A. Lasenby; R. J. Laureijs; A. Lavabre; C. R. Lawrence; S. Leach; R. Lee; R. Leonardi; C. Leroy; P. B. Lilje; M. L�pez-Caniego; P. M. Lubin; J. F. Mac�as-P�rez; T. Maciaszek; C. J. MacTavish; B. Maffei; D. Maino; N. Mandolesi; R. Mann; M. Maris; E. Mart�nez-Gonz�lez; S. Masi; S. Matarrese; F. Matthai; P. Mazzotta; P. McGehee; P. R. Meinhold; A. Melchiorri; F. Melot; L. Mendes; A. Mennella; M.-A. Miville-Desch�nes; A. Moneti; L. Montier; J. Mora; G. Morgante; N. Morisset; D. Mortlock; D. Munshi; A. Murphy; P. Naselsky; A. Nash; P. Natoli; C. B. Netterfield; D. Novikov; I. Novikov; I. J. O'Dwyer; S. Osborne; F. Pajot; F. Pasian; G. Patanchon; D. Pearson; O. Perdereau; L. Perotto; F. Perrotta; F. Piacentini; M. Piat; S. Plaszczynski; P. Platania; E. Pointecouteau; G. Polenta; N. Ponthieu; T. Poutanen; G. Pr�zeau; M. Prina; S. Prunet; J.-L. Puget; J. P. Rachen; R. Rebolo; M. Reinecke; C. Renault; S. Ricciardi; T. Riller; I. Ristorcelli; G. Rocha; C. Rosset; J. A. Rubi�o-Mart�n; B. Rusholme; M. Sandri; D. Santos; G. Savini; B. M. Schaefer; D. Scott; M. D. Seiffert; P. Shellard; G. F. Smoot; J.-L. Starck; P. Stassi; F. Stivoli; V. Stolyarov; R. Stompor; R. Sudiwala; J.-F. Sygnet; J. A. Tauber; L. Terenzi; L. Toffolatti; M. Tomasi; J.-P. Torre; M. Tristram; J. Tuovinen; L. Valenziano; L. Vibert; P. Vielva; F. Villa; N. Vittorio; A. Wilkinson; B. D. Wandelt; C. Watson; S. D. M. White; P. Wilson; D. Yvon; A. Zacchei; B. Zhang; A. Zonca
Driving Miss Bradley: performance measurement to support thermal driving
The Driver's Vision Enhancer (DVE) program is providing a system to enlarge the driving envelope for the community of military wheeled and tracked vehicles. The DVE, an IR device, provides the driver with images of the forward scene under night and adverse day conditions. During the DVE development program, several questions emerged requiring performance-based data to resolve. A comprehensive program to provide the Project Manager, Night Vision/Reconnaissance, Surveillance and Target Acquisition with driver performance data that will aid in the decision-making process is described in this paper. The program involves several linked efforts including: the relative merits of the DVE and night vision goggles (NVG); drivers' ability to detect the presence of drop-offs when using the DVE and NVG; the effect on performance of various levels of nonuniformity and nonresponsiveness in the display/sensor system; the analysis of drivers' vision using an eye-tracker in a vehicle; and the evaluation of candidate symbology to enhance the DVE's utility in the M2 Bradley. The data collected will aid in making decisions on how to write a system specification to reduce cost without sacrificing driver performance, gain an understanding of how drivers use the DVE in operational settings, and determine where training is needed to enhance safety and reduce risk on the battlefield.
Piccione, Dino; Ferrett, Donald A.
Analytical and experimental investigations into the performance of a double-pass photovoltaic thermal solar collector
This study presents analytical and experimental investigations of a double-pass photovoltaic thermal solar air collector. Photovoltaic thermal collector is a combination of thermal and photovoltaic systems. It generates both thermal and electrical energies simultaneously. An experimental setup of a double-pass photovoltaic thermal solar air collector was designed and fabricated to study the performance over a range of design and operating conditions. A set of steady-state energy balance equations was formulated for the two air streams, the glass cover, the photovoltaic panel, and the back-plate. These equations were reduced to a set of two differential equations, and a closed-form solution was obtained. Reasonably close agreements between the analytical and experimental results were obtained. This model was used to simulate the performance of larger double-pass photovoltaic thermal system by varying the photovoltaic length, packing factor, air mass flow rate and channel depth. The minimum area of the photovoltaic cell necessary to generate sufficient electrical energy to run the fan at a given mass flow rate was also calculated as a function of time for different configurations of the collector. Several important relationships between the design and operating conditions were obtained. These relationships affected the performance of the double-pass photovoltaic thermal solar collector. Hence, design curves for the photovoltaic thermal solar collector were developed. The designer would be able to predict the performance of the system using the design curves by selecting the required conditions. This includes the effects of changing the channel depth and air mass flow rate on the global solar radiation, thermal, photovoltaic and combined thermal photovoltaic efficiencies, and temperature rise of the collector. An economic optimization model was developed to study the effect of combinations of mass flow rates, photovoltaic panel length and channel depth on the cost-benefit ratio of the collector. The user could select the optimum design features that correspond to minimum cost-benefit ratio.
Sopian, Kamaruzzaman Bin
Reclaimed manufacturer asphalt roofing shingles in asphalt mixtures. Final research report
The purpose of this project was to pave a test section using hot mix asphalt with roofing shingle pieces in the wearing and binder courses and to evaluate. The test project near Allentown, PA plus two other test projects in 1998 provide evidence of very good pavement performance. The bituminous concrete mix was modified with shredded shingles with a maximum size of 1/2 inch which added 1% of the asphalt content. The Department issued a statewide Provisional Specification titled Reclaimed Manufacturer Asphalt Roofing Shingles in Plant-Mixed Bituminous Concrete Courses'' on March 15, 1999. New manufacturer asphalt roofing shingle scrap including tab punch-outs can be successfully incorporated in bituminous concrete pavements if the shingles are shredded to 100% passing the 3/4 inch sieve. To take full advantage of the potential to replace a portion of the asphalt and therefore, reduce mix costs, shingles should be shredded to 100% passing minus 1/2 inch sieve.
Reed, A.B.
The Class II Thermal Imaging Common Modules were originally developed for the U.K. Ministry of Defence as the basis of a number of high performance thermal imaging systems for use by the British Armed Forces. These systems are characterized by high spatial resolution, high thermal resolution and real time thermal image update rate. A TICM II thermal imaging system uses a cryogenically cooled eight element Cadmium- Mercury-Telluride (CMT) SPRITE (Signal PRocessing In The Element) detector which is mechanically scanned over the thermal scene to be viewed. The TALYTHERM system is based on a modified TICM II thermal image connected to an IBM PC-AT compatible computer having image processing hardware installed and running the T.E.M.P.S. (Thermal Emission Measurement and Processing System) software package for image processing and data analysis. The operation of a TICM II thermal imager is briefly described highlighting the use of the SPRITE detector which coupled with a serial/parallel scanning technique yields high temporal, spatial and thermal resolutions. The conversion of this military thermal image into thermography system is described, including a discussion of the modifications required to a standard imager. The technique for extracting temperature information from a real time thermal image and how this is implemented in a TALYTHERM system is described. The D.A.R.T. (Discrete Attenuation of Radiance Thermography) system which is based on an extensively modified TICM II thermal imager is also described. This system is capable of measuring temperatures up to 1000 degrees C whilst maintaining the temporal and spatial resolutions inherent in a TICM II imager. Finally applications of the TALYTHERM in areas such as NDT (Non Destructive Testing), medical research and military research are briefly described.
Bell, Ian G.
Thermal performance assessment of an advanced glazing system
The four different techniques which were used to test an advanced, four-pane glazing system and standard double-glazed unit are described. The results from each test are compared. Where agreement is not good, explanations are suggested. The advanced glazing system was found to have a U-value of 0.9 W/m[sup 2] K and a shading coefficient of 0.48. The glazing simulation models WINDOW (Lawrence Berkeley Laboratories, Berkeley, CA, US) and MULTB (Pilkington Glass, U.K.) were used to predict glazing performance. Simulation of the two glazing systems which were experimentally assessed allows comparison between models, and between predicted and measured performance. Agreement was within the error bands associated with each assessment. 7 refs., 2 figs., 1 tab.
Robinson, P. (Architectural Association, London (United Kingdom)); Littler, J. (Univ. of Westminster, London (United Kingdom))
Thermal performance of a new solar air heater
A solar air heater, part of a food drying system using solar energy as a renewable energy source for heat, was developed and tested for several agricultural products (i.e., sultana grapes, green beans, sweet peppers, chili peppers). Drying processes were conducted in the chamber with forced natural air heated partly by solar energy. Solar air heater performances were discussed along with estimates of energy efficiency of the system. The obtained results indicate that the present system is efficiency and effective.
Tiris, C.; Ozbalta, N. [Ege Univ., Izmir (Turkey). Solar Energy Institute] [Ege Univ., Izmir (Turkey). Solar Energy Institute; Tiris, M.; Dincer, I. [TUBITAK-Marmara Research Center, Kocaeli (Turkey)] [TUBITAK-Marmara Research Center, Kocaeli (Turkey)
Experimental investigation of nanofluids on sintered heat pipe thermal performance
Dilute dispersion of silver nano-particles in pure water was employed as the working fluid for conventional 1mm wick-thickness sintered circular heat pipe. The nanofluid used in present study is an aqueous solution of 10 and 35nm diameter silver nano-particles.The experiment was performed to measure the temperature distribution and compare the heat pipe temperature difference using nanofluid and DI-water. The tested
Shung-Wen Kang; Wei-Chiang Wei; Sheng-Hong Tsai; Chia-Ching Huang
Thermal and hydraulic performance of a graphite block heat exchanger
A test rig has been assembled to investigate the thermodynamic and hydraulic performance of a cylindrical graphite block heat exchanger consisting of three graphite blocks and a steel shell. The flow pattern in the heat exchanger was triple cross-flow on the shell-side (service side) with one pass per block and a single pass on the tube-side (process side). Overall heat
G. Schou; J. Deans; J. K�nzel; H. M�ller-Steinhagen
Thermal Performance Comparison of Glass Microsphere and Perlite Insulation Systems for Liquid Hydrogen Storage Tanks
A technology demonstration test project was conducted by the Cryogenics Test Laboratory at the Kennedy Space Center (KSC) to provide comparative thermal performance data for glass microspheres, referred to as bubbles, and perlite insulation for liquid hydrogen tank applications. Two identical 1/15th scale versions of the 3,200,000 liter spherical liquid hydrogen tanks at Launch Complex 39 at KSC were custom designed and built to serve as test articles for this test project. Evaporative (boil-off) calorimeter test protocols, including liquid nitrogen and liquid hydrogen, were established to provide tank test conditions characteristic of the large storage tanks that support the Space Shuttle launch operations. This paper provides comparative thermal performance test results for bubbles and perlite for a wide range of conditions. Thermal performance as a function of cryogenic commodity (nitrogen and hydrogen), vacuum pressure, insulation fill level, tank liquid level, and thermal cycles will be presented.
Sass, J. P.; Fesmire, J. E.; Nagy, Z. F.; Sojourner, S. J.; Morris, D. L.; Augustynowicz, S. D.
Structural-thermal-optical performance (STOP) sensitivity analysis for the James Webb Space Telescope
The James Webb Space Telescope (JWST) is a key component of NASA's Origins Program to understand the origins and future of the universe. JWST will be used to study the birth and formation of galaxies and planets. The mission requires a large (25m2 aperture) but extremely stable (150 nm RMS wave front error) optical platform, where performance is a tightly coupled function of numerous physical processes. Distortion due to thermal loading is a significant error source. The process by which predicted heat loads are mapped to optical error is termed Structural-Thermal-Optical Performance (STOP) modeling. Thermal-optical performance is a function of heat loads, thermal properties (conductivities, radiative coupling coefficients), structural properties (moduli, geometry, thermal expansion coefficients, ply layup angles), and optical sensitivities. Sensitivities, the gradients of performance with respect to design parameters, give a direct way to identify the parameters that have the largest influence on performance. Additionally, gradients can identify the largest sources of uncertainty, and thus contribute to improving the robustness of the design, either via redesign or by placing requirements on parameter variability. The paper presents a general framework for developing the analytical sensitivities of the STOP prediction using the Chain Rule. The paper focuses on solving for the sensitivities of the steady-state, conduction-only, problem, using discipline modeling tools (thermal, structural, and optical) to compute the terms in the STOP gradients. The process is demonstrated on the SDR2 Rev. 1 cycle of the JWST modeling effort.
Blaurock, Carl; McGinnis, Mark; Kim, Kevin; Mosier, Gary E.
Recovery and reuse of asphalt roofing waste: incorporation of roofing waste in asphalt paving. Volume 2. Laboratory investigation
Laboratory test results obtained in this preliminary study indicate the following: Acceptable paving mixtures can be produced which contain 20 vol % roofing waste. With a proper selection of binder type, binder quantities, and aggregate gradations, mixtures containing roofing waste quantities to and perhaps beyond, 30% can probably be prepared with acceptable properties. The type of binder selected for use in a mixture containing roofing waste should be based on the stiffness (penetration and viscosity) of the asphalt cement in the roofing waste. Improved asphalt cement extraction and recovery processes need to be developed for roofing wastes in order to effectively determine the properties of the asphalt cement in the roofing waste. Gradations of conventional aggregates and roofing wastes should be considered when designing paving mixtures.
Paulsen, G.; Stroup-Gardiner, M.; Epps, J.A.
WIPP supplementary roof support system Room 1, Panel 1: Geotechnical field data analysis report
The design of the Room 1, Panel 1, supplementary roof support system was finalized in September 1991, and the system successfully installed in the test bin area between the bulkheads by December 1991. Simultaneously with the support system installation, existing monitoring system was upgraded to meet the needs of the installed roof support. This included extensometers, closure stations, rockbolt load cells as well as survey measurements of roof sag and floor lift. A Project Control Group (PCG) was established in order to monitor room and support system performance. Weekly meetings of the PCG were held to review all monitored data against criteria set in the initial design, and to modify these where necessary. Records of these meetings have been kept, with copies of all data summaries and action notes. These data records are maintained in the Engineering data files. After more than ten months of monitoring and reviewing experience, several modifications have been made both to the way data has been reported as well as to the load adjustment criteria. The support system has performed as expected in the design, with no signs of instability developing considering the rates of roof deformation, the rock bolt loads and the observed fracture behavior in the roof. This is particularly true of the horizon in which the rockbolt anchors are located, the most critical part of the design. The distribution of load build-up, throughout the 286 rockbolt load cells installed, in the Room 1 has been found satisfactory, and the load increases as evaluated by the PCG on a weekly basis have been within the acceptable range. The minimum life of the installed support system is estimated at 15 years based on the highest roof expansion rate experienced to date. This report provides analysis of geotechnical field data collected up to December 1992.
The thermal performance of heat pipes with localized heat input
The performance of heat pipes with localized heat input including the effects of axial and circumferential heat conduction under high and low working temperatures is investigated. The numerical results show that when heat pipes are spot heated, the peak temperature of the wall is greatly reduced and the surface can be protected from being burned out by the high heat flux. The boiling limitation becomes the most important limitation for this type of heat pipe. Numerical results for block heating a heat pipe with low working temperatures indicate a good agreement with existing experimental data. It is also shown that most of the input heat passes through the wall beneath the heated block.
Cao, Yiding; Faghri, Amir; Mahefkey, E. T.
Procedure calculates benefits of tank roof seals
Installation of primary and secondary seals on floating-roof, oil-storage tanks can be a matter both of regulatory compliance and economic good judgment. In the U.S., federal and state regulations often require such installation. But where regulatory incentives are absent, there is a simple set of calculations to determine the economic benefits of primary-seal repair/replacement and/or addition of secondary seals. Early in 1976, floating-roof-tank seals were inspected at a California refinery by local air-pollution-control officials. As a result of that inspection, accusations were made of massive emissions from poorly maintained seals. In fact, this particular refinery was accused of emitting approximately 3,000 tons of hydrocarbons per year. This number was arrived at by calculating the emissions based upon the then-current edition of the American Petroleum Institute's bulletin API 2517 and multiplied by a factor of 4 to account for poor seal condition.
Thiltgen, R.W.
Use of the finite element method to predict roof collapse and subsidence resulting from the underground gasification of coal
The plane strain two-dimensional finite element model employing the method of negative reaction loading was used to model roof collapse and subsidence that result from underground coal gasification. Subsidence results from a preliminary finite element model were compared with those from a theoretical model having identical assumptions. The finite element model was extended to include dry zones of rock around the cavity resulting from the underground gasification. The model was further extended to include thermal loading, thermal softening and roof collapse. Roof collapse initiation and growth were modelled by examining the portion of the roof immediately above the cavity. A creep program utilizing the method incremental strains was developed and run in conjunction with the Pafec 70 + program. The overburden rock was treated as a linear viscoelastic material having deformation parameters of the generalized Kelvin model. Finally, the finite element model was used to carry out a case history study of subsidence and roof collapse of an underground gasification field experiment in Wyoming.
Jegbefume, E.U.
Installation of primary and secondary seals on floating-roof, oil-storage tanks can be a matter both of regulatory compliance and economic good judgment. In the U.S., federal and state regulations often require such installation. But where regulatory incentives are absent, there is a simple set of calculations to determine the economic benefits of primary-seal repair\\/replacement and\\/or addition of secondary seals. Early
30 CFR 75.222 - Roof control plan-approval criteria.
...on at least 5-foot centers where the work is performed. (2) Where the roof...centers across the opening before any other work or travel in the intersection. (f...panel in advance of the frontal abutment stresses of the panel being mined. (2)...
The purpose of this project was to pave a test section using hot mix asphalt with roofing shingle pieces in the wearing and binder courses and to evaluate. The test project near Allentown, PA plus two other test projects in 1998 provide evidence of very good pavement performance. The bituminous concrete mix was modified with shredded shingles with a maximum
This patent describes a vertical cylindrical liquid storage tank having a circular floating roof of smaller diameter than the tank thereby defining a clearance space between the roof edge and the tank wall; a seal joined to the roof and extending upwardly therefrom into slidable contact with the tank wall; the seal completely covering the clearance space; the seal comprising a plurality of individual flexible sections of sheet material in substantially side-by-side arrangement but with adjacent section side edge portions overlapping each other; a gasket between the overlapping side edge portions; a clip attached to each section adjacent its edge portion which is overlapped by the edge portion of an adjacent section; the clip having a wing spaced upward from the section to which it is attached and extending over the edge portion of the adjacent section to press the edge portions together, but permit the edge portions to slide laterally with respect to each other; and a flexible elastometric tip joined to the outer end of the sections and in slidable contact with the tank wall.
Grove, R.B.; Peters, S.W.; Tellalian, M.L.
Thermal\\/fluid performance evaluation of serrated plate fin heat sinks
Cooling of the electronics in people movers and other rail transportation systems require the removal of high power dissipation from the electronic equipment to ensure their long term reliability and performance. In this study, the thermal performance of in-service serrated plate fin heat sink is evaluated for a range of Reynolds number by means of fully three-dimensional numerical simulations of
Ibraheem K. Shwaish; Cristina H. Amon; J. Y. Murthy
Thermal performance of the Peterson Residence: a double shell envelope house
The Peterson Residence is a double shell envelope house located near Baltimore, MD and designed for the temperature climate of the Middle Atlantic Region. A multipoint strip chart recorder was installed in February 1981 to continuously monitor the thermal performance throughout the year. This report is based upon the preliminary data collected during March 1981. Performance results are presented and
Simulation and experiment on the thermal performance of U-vertical ground coupled heat exchanger
This paper presented both the numerical simulations and experiments on the thermal performance of U-vertical ground coupled heat exchanger (UGCHE). The variation of the ground temperature and heat balance of the system were analyzed and compared in different operation modes in the numerical simulation. Experiments on the operation performance of the ground-coupled heat pump (GCHP) with the UGCHE were carried
Xinguo Li; Zhihao Chen; Jun Zhao
Performance of abutment�backfill system under thermal variations in integral bridges built on clay
In this paper, performance of the abutment�backfill system under thermal variations is studied. For this purpose, a structural model of a typical integral bridge is built considering the nonlinear behavior of the piles and soil�bridge interaction effects. Static pushover analyses of the bridge are conducted to study the effect of various geometric, structural and geotechnical parameters on the performance of
Murat Dicleli; Suhail M. Albhaisi
Largo hot water system long range thermal performance test report, addendum
The test procedure used and the test results obtained during the long range thermal performance tests of the LARGO Solar Hot Water System under natural environmental conditions are presented. Objectives of these tests were to determine the amount of energy collected, the amount of power required for system operation, system efficiency, temperature distribution, and system performance degradation.
Plasticity of Size and Growth in Fluctuating Thermal Environments: Comparing Reaction Norms and Performance Curves
SYNOPSIS. Ectothermic animals exhibit two distinct kinds of plasticity in response to temperature: Thermal performance curves (TPCs), in which an individual's performance (e.g., growth rate) varies in response to current temperature; and developmental reaction norms (DRNs), in which the trait value (e.g., adult body size or development time) of a genotype varies in response to developmental temperatures experienced over some
Characterization of Hollow Cathode Performance and Thermal Behavior
Hollow cathodes are one of the main life-limiting components in ion engines and Hall thrusters. Although state-of-the-art hollow cathodes have demonstrated up to 30,352 hours of operation in ground tests with careful handling, future missions are likely to require longer life, more margin and greater resistance to reactive contaminant gases. Three alternate hollow cathode technologies that exploit different emitter materials or geometries to address some of the limitations of state-of-the