This study develops a set of CO2 transcritical automobile heat pump air-conditioning systems

which adopts a CO2 vehicle electrical compressor

micro-channel heat exchanger

electronic expansion valve and other key components. This is to overcome technical challenges brought by CO2 automobile’s heat pump air-conditioning system such as high pressure and high exhaust temperature. The effects of the amount of system refrigerant charge on the system performance

circulation characteristics

and the expansion valve opening of the CO2 automobile heat pump air-conditioning are studied in this paper. In addition

this paper proposes a series of indoor heat exchangers to increase the heat transfer capacity of the high-pressure side in the heat pump mode

and experimentally verifies the effect of this method on automobile heat pump air-conditioning system performance. Results show that compared with the single gas cooler

the automobile heat pump air-conditioning system with series gas coolers achieves an increase in heating capacity of 17-31% and coefficient of performance（COPh）of 20-33%. The system can generate 40.4 °C gas cooler outlet air and COPh = 1.8 under the environment of﹣20 ℃ fresh air mode. Therefore

the developed CO2 automobile heat pump air-conditioning system can satisfy passenger comfort and vehicle load demand under a low-temperature environment for electric vehicles and has a very significant advantage in heating energy efficiency.