FUNDAMENTAL ASPECTS OF THE APPLICATION OF CARBON DIOXIDE IN COMFORT COOLING

This paper presents entropy generation analyses for the evaporator, compressor, gas cooler, expansion device and liquid-line suction-line heat exchanger for a transcritical carbon dioxide cycle for automotive and residential air-conditioning systems, and presents entropy generation analyses for the evaporator, compressor, condenser, and expansion device for a subcritical R134a automotive air-conditioning system and a subcritical R22 residential air-conditioning system. The analyses show that the CO2 automotive air-conditioning system generates 36 % more entropy than the R134a automotive air-conditioning system, and that the CO2 residential air-conditioning system generates 63 % more entropy than the R22 residential air-conditioning system. The biggest contributors to the lower CO2 performance are irreversibilities associated with the heat rejection process and the expansion related processes