Low-temperature heating characteristics of an electric vehicle compressor using R1270

To explore the application potential of low-GWP natural refrigerants in electric vehicle heat pump air-conditioning systems, R1270 was selected as the working fluid and its compressor heating performance was analysed based on a low-temperature electric vehicle scroll compressor test platform. The operating conditions included evaporation temperatures of −10°C, −15°C and −20°C, condensation temperatures of 40°C and 50°C, compressor speeds of 3000–7500 r/min, 10°C superheat and 5°C subcooling. The results show that compressor power and heating capacity increased approximately linearly with rotational speed. Under the −10°C/40°C condition, the compressor power increased from about 1.6 to 4.2 kW, while the heating capacity rose from about 6.1 to 14.8 kW. The maximum COP was about 3.87 under the −10°C/40°C condition, whereas the minimum COP was about 2.56 under the −20°C/50°C condition. The isentropic efficiency decreased with increasing speed, while the volumetric efficiency first increased slightly and then declined, remaining above 0.876 even under severe operating conditions. The oil circulation rate increased with speed and was strongly affected by evaporation temperature. The discharge temperature was mainly governed by evaporation and condensation temperatures, reaching about 89.0°C under the −20°C/50°C condition. Overall, R1270 shows favourable heating performance and potential for low-temperature electric vehicle heat pump compressor applications.