Heating performance characteristics of CO2 heat pump system for electrical vehicle in a cold climate

This study investigated the heating performance characteristics of a CO2 heat pump system for an electrical vehicle in a cold climate. Experimental tests evaluated the effects on system performance of outdoor temperature, outdoor air velocity, indoor temperature, indoor air flow rate, compressor speed, and EXV opening. The results of heating experiments when both the indoor and outdoor temperatures were −20 °C showed a coefficient of performance (COP) of 3.1 and a heating capacity of 3.6 kW. The COP was 1.7 when the outdoor, indoor air inlet, and outlet temperature were −20 °C, 20 °C, and 40 °C, respectively. Therefore, the heat pump using CO2 refrigerant achieved good heating performance in a cold climate. Additionally, a new secondary loop heat pump was also compared with the conventional heat pump, and the test results show that use of the secondary loop heat pump reduced COP by 19%.