Experimental Study on Heating Performance of an R1234yf Heat Pump System for Electric Cars

An R1234yf heat pump system with a secondary fluid circle is designed to lower the risk of high voltage power for supplement heating of electric cars. Heating performance of the test system affected by the expander valve opening and working conditions is investigated. Increasing EXV opening can benefit for heating performance to some degree: COP increases from 3.08 to 4.44 at 3000RPM and 2.38 to 2.72 at 5000RPM; compressor isentropic efficiency increases from 0.951 to 0.974 at 3000RPM and 0.945 to 0.954 at 5000RPM. The experimental results show that heating capacity of the R1234yf heat pump system reduces around 37.2% from 3577W to 2246W with the deceasing of ambient temperature from 0 degrees C to -10 degrees C at 5000RPM. It is very necessary to optimize the operation mode of heat pump and PTC heater based on the comprehensive efficiency. (C) 2017 The Authors. Published by Elsevier Ltd.