Experimental investigation of energy and exergy performance of secondary loop automotive air-conditioning systems using low-GWP (global warming potential) refrigerants

In this study, the energy and exergy performance of secondary loop systems (2LPs) using HFC-152a and HC-290 was investigated. These 2LPs were compared with a HFC-134a direct expansion system as a baseline system. As compared with the baseline, tested refrigerant charge amount was reduced by 28% for the HFC-152a 2LP and 60% for the HC-290 2LP. Under typical 35 °C ambient temperature condition, the coefficient of performance (COP) of the HFC-152a 2LP was increased by 5% for highway driving conditions and 10% for idling conditions. Regarding the HC-290 2LP, the COP was increased by 8% under highway driving conditions and was decreased by 15% under idling conditions. As for the exergy performance, the total exergy destruction was reduced by roughly 9.6% for the HFC-152a 2LP and 14.3% for the HC-290 2LP as compared with HFC-134a baseline during highway driving conditions. A theoretical potential of HC-290 2LP idling performance is that its idling COP would be approximately 15% higher and its exergy destruction would be 12.5% lower than those of the HFC-134a baseline.