Analyses of an integrated thermal management system for electric vehicles

Electric vehicle thermal management system (EVTMS) is a promising method to solve cabin thermal comfort and electronics waste heat. In this paper, an integrated EVTMS combining heat pump, battery cooling, and motor waste heat recovery was proposed. EVTMS performance tests were firstly carried out in the environment chamber with variations of refrigerant charge, electronic expansion valve (EXV) opening, compressor speed, environmental temperature, and waste heat amount. Moreover, the comprehensive energy, exergy, and thermo-economy analyses for EVTMS were performed based on the experimental results. The results demonstrate that the optimum refrigerant charge for baseline EVTMS is 810 g, and the optimum EXV opening is in the range of 70% to 90%. Accordingly, the percentage of cooling capacity reduction (PCCR) and the percentage of waste heat recovery (PWHR) are in the range of 26.3% to 32.1% and 18.73% to 45.17%, respectively. The exergy destruction ratio of the scroll compressor and external heat exchanger is more than 80%. With the utilization of the proposed EVTMS, the operation cost per hundred kilometers for heating mode is decreased 20.83% compared with that of positive temperature coefficient heaters.