Performance analysis and operation strategy of a dual-evaporation temperature heat pump system for electric vehicles in winter

With increasingly serious environmental and energy issues, efficient and environmentally friendly electric ve-hicles have received more attention. However, the high heating and dehumidification energy consumption of their air conditioning system reduces their driving range in winter, giving passengers and drivers range anxiety. In this study, a dual-evaporation temperature heat pump system is proposed to reduce the energy consumption of electric vehicle air conditioning systems in winter, and a simulation model of the proposed system is developed. First, the volume ratio of the dual-cylinder compressor is optimized. Subsequently, the performance of the proposed system in various operation modes under different ambient conditions is compared. The results indicate an optimized volume ratio of 2.85, which is taken as the system's design condition. The dual-evaporation temperature heating dehumidification mode shows superior performance compared with the conventional mode under typical winter conditions in three different climatic zones. Moreover, energy consumption can be reduced by reasonably controlling the operation mode based on ambient conditions. An operation strategy for the dual-evaporation temperature heat pump system in winter is proposed through the regional division of the psychrometric chart, and the energy-saving operation mode of the system is analyzed for different climate zones in China.