condenser is a heat exchanger which allows heat to migrate from the refrigerant gas to either water or air. Air cooled condenser are manufactured from copper tubes (for the refrigerant flow) and aluminium fins (for the air flow). Each condenser has a different material cost and they vary in terms of efficiency. With evaporative cooling condensers, their coefficients-of-performance (COPs) are very high; typically 4.0 or more. Air cooled condensers are installed and operated outdoors and are cooled with outside air, that is often forced through the condenser using electric fans. Water or liquid cooled condensers are cooled with water that is often in turn cooled by a cooling tower. The expansion device or refrigerant metering device (RMD) restricts the flow of the liquid refrigerant causing a pressure drop that vaporizes some of the refrigerant; this vaporization absorbs heat from nearby liquid refrigerant. The RMD is located immediately prior to the evaporator so that the cold gas in the evaporator can absorb heat from the water in the evaporator. There is a sensor for the RMD on the evaporator outlet side which allows the RMD to regulate the refrigerant flow based on the chiller design requirement. Evaporators can be plate type or shell and tube type. The evaporator is a heat exchanger which allows the heat energy to migrate from the water stream into the refrigerant gas. During the state change of the remaining liquid to gas, the refrigerant can absorb large amounts of heat without changing temperature. How absorption technology works The thermodynamic cycle of an absorption chiller is driven by a heat source; this heat is usually delivered to the chiller via steam, hot water, or combustion. Compared to electrically powered chillers, an absorption chiller has very low electrical power requirements – very rarely above 15 kW combined consumption for both the solution pump and the refrigerant pump. However, its heat input requirements are large, and its COP is often 0.5 (single-effect) to 1.0 (double-effect). For the same cooling capacity, an absorption chiller requires a much larger cooling tower than a vapor-compression chiller. However, absorption chillers, from an energy-efficiency point of view, excel where cheap, low-grade heat or waste heat is readily available. In extremely sunny climates, solar energy has been used to operate absorption chillers. The single-effect absorption cycle uses water as the refrigerant and lithium bromide as the absorbent. It is the strong affinity that these two