using zeotropic mixtures. This includes leakages, as well as the high temperature glide associated with substances of different boiling points, though the temperature glide can be matched to the temperature difference between the two refrigerants when exchanging heat to increase efficiency. Replacing pure refrigerants with mixtures calls for more research on the environmental impact as well as the flammability and safety of refrigerant mixtures. Organic Rankine cycle In the Organic Rankine Cycle (ORC), zeotropic mixtures are more thermally efficient than pure fluids. Due to their higher boiling points, zeotropic working fluids have higher net outputs of energy at the low temperatures of the Rankine Cycle than pure substances. Zeotropic working fluids condense across a range of temperatures, allowing external heat exchangers to recover the heat of condensation as a heat source for the Rankine Cycle. The changing temperature of the zeotropic working fluid can be matched to that of the fluid being heated or cooled to save waste heat because the mixture's evaporation process occurs at a temperature glide (see Pinch Analysis). R21/R245fa and R152a/R245fa are two examples of zeotropic working fluids that can absorb more heat than pure R245fa due to their increased boiling points. The power output increases with the proportion of R152a in R152a/R245fa. R21/R245fa uses less heat and energy than R245fa. Overall, zeotropic mixture R21/R245fa has better thermodynamic properties than pure R245fa and R152a/R245fa as a working fluid in the ORC. Cleaning processes Zeotropic mixtures can be used as solvents in cleaning processes in manufacturing. Cleaning processes that use zeotropic mixtures include cosolvent processes and bisolvent processes. Cosolvent and bisolvent processes In a cosolvent system, two miscible fluids with different boiling points are mixed to create a zeotropic mixture. The first fluid is a solvating agent that dissolves soil in the cleaning process. This fluid is an organic solvent with a low-boiling point and a flash point greater than the system's operating temperature. After the solvent mixes with the oil, the second fluid, a hydrofluoroether rinsing agent (HFE), rinses off the solvating agent. The solvating agent can be flammable because its mixture with the HFE is nonflammable. In bisolvent cleaning processes, the rinsing agent is separated from the solvating agent. This makes the solvating and rinsing agents more effective because they are not diluted. Cosolvent systems are used for heavy oils, waxes, greases and fingerprints, and can remove heavier soils than processes that use pure or