WET COMPRESSION VERSUS DRY COMPRESSION IN HEAT-PUMPS WORKING WITH PURE REFRIGERANTS OR NONAZEOTROPIC MIXTURES

The principle of wet compression seems particularly attractive for heat pumps using non-azeotropic mixtures, because in this type of heat pump the desorption process is in most cases incomplete. Wet compression should a priori also be attractive for compression cycles using a pure refrigerant. A detailed study shows that although this is the case for the ideal cycle with most refrigerants, all advantages of wet compression are lost when the cycle's irreversibilities, such as isenthalpic expansion and non-isentropic compression, are taken into account. The thermodynamic analysis of wet compression for cycles using nonazeotropic mixtures leads to the conclusion that the solution recirculation cycles offer a good technical solution, in spite of the theoretical advantages of total wet compression, which allows, within the limits of the present analysis (fixed overall concentration, no dependence of the external conditions), for better performances. Whether it will also be so in practice depends inter alia on the isentropic efficiency of the compressor.