Second-law-based thermodynamic analysis of vapor-compression refrigeration cycles.

摘要

Thermodynamic analysis of vapor-compression refrigeration cycles are investigated by both the first law and second law of thermodynamics. It is found that most of the irreversibility (energy loss) is in the compressor due to low compressor efficiency. Irreversibilities of the expansion valve as well as condenser are also significant. These irreversible losses increases with the increase of condenser and evaporator temperature differences.;The staging of compressors of a refrigerating system produces a saving in work. In this study, it is found that the optimum interstage pressure for a two-stage, vapor-compression refrigeration cycle is very close to the saturation pressure corresponding to the arithmetic mean of the condensing and evaporating temperatures. (Abstract shortened by UMI.).;A new refrigerant R-134a is also investigated, which is considered as a leading candidate to replace R-12. A comparative study is also done between these two refrigerants which indicate that R-12 can be replaced by R-134a, without any significant loss in overall system performance.