Performance Evaluation of CO2/R1270 Heat Pump System With Internal Heat Exchanger for Electric Vehicles

Abstract The CO2/R1270 mixture is recognized for its environmental compatibility, with system pressure reduction and energy efficiency enhancement being simultaneously achieved. A novel CO2/R1270 heat pump system with internal heat exchanger (IHX) for electric vehicles (EV) is proposed. Comprehensive evaluation models incorporating economic and environmental metrics were developed, with comparative analysis conducted against positive temperature coefficient (PTC) heating systems. Performance analysis across three climatic zones (Harbin, Tianjin, and Guangzhou) was systematically performed to assess geographical adaptability. The results demonstrate that Guangzhou's annual cooling energy consumption (253.8 kWh) was 2.39 times higher than Tianjin's, while its heating demand represented only 10.1% of Tianjin's. A latitudinal dependence was observed, with heating energy decreasing and cooling demand increasing proportionally to latitude reduction. The PTC system exhibited 80.74%, 80.65%, 80.7%, and 82.13% higher emissions of PM10, PM2.5, SO2, and NOx, respectively, compared to the heat pump. The total equivalent warming impact (TEWI) was quantified to be fivefold greater in PTC systems. Superior economic performance was demonstrated by the cabin evaporator, while the compressor was identified as requiring cost-reduction optimization due to high capital investment. Additional improvement potential was recognized in the heat exchanger and gas cooler configurations.