Investigation on the performance enhancement of electric vehicle heat pump system with air-to-air regenerative heat exchanger in cold condition

Abstract

Since the heat pump operation in low ambient temperature requires considerable amount of electric energy, electric vehicles (EVs) suffer from the significant range loss problem in cold regions. In this study, heat pump system with air-to-air regenerative heat exchanger (ARHX) is suggested as a way to improve the energy inefficiency in the ventilation or dehumidification process. In recirculation mode, ARHX reduces heating and dehumidification load by utilizing the temperature difference of two air streams, occurring in the subsequent dehumidification and heating process. In outdoor air mode, ARHX enhances heating performance by recovering the heat from the preconditioned cabin air, which is exhausted to the environment in conventional heat pump system. Heat pump model was built upon an experimentally validated component model and thermal load model. Based on this heat pump model, performance enhancement of the proposed system is investigated in both recirculation and outdoor air mode with various climate conditions. Results confirm that suggested heat pump system decreases heating load and dehumidification load up to 12.3% and 12.9% in recirculation mode and the heating load reduction reaches 20.2% in outdoor air mode. Power consumption of the compressor is saved up to 10.6% in recirculation mode and 55% in outdoor air mode.