Heating performance evaluation of a CO2 heat pump system for an electrical vehicle at cold ambient temperatures

A novel CO2 heat pump system with Series Gas Cooler (SGC) configuration was proposed for application in an Electrical Vehicle (EV). A newly developed mobile CO2 compressor with 6.8 ml displacement and 8000 RPM maximum speed was employed. The heating performance of this CO2 heat pump system was experimentally evaluated under low temperature conditions. Comparison experiments were conducted to reveal the effects of CO2 refrigerant charge, GC configuration and indoor return air ratio on heating performance characteristics. Results show that using SGC improves the heating capacity and COP by up to 33% and 32%, respectively, compared with One Gas Cooler (OGC). At the extreme cold temperature of −20 °C, the novel CO2 heat pump system achieved 5.6 kW maximum heating capacity and 1.8 COP, which greatly outperforms the conventional PTC heating supplement for an EV.