Improving the long-term performance of electric vehicles CO2 heat pump through correcting discharge pressure

Abstract

Electric vehicle CO2 heat pumps are an environmentally friendly and energy-efficient solution, especially in cold regions, where they show exceptional heating capabilities and attract widespread attention. The optimal discharge pressure has consistently been the focus of research for enhancing energy efficiency in CO2 heat pump systems. The impact of declining heat transfer efficiency during the long-term operation on the optimal discharge pressure has yet to be thoroughly investigated. Establishing a simulation model for electric vehicles CO2 heat pump. Considering how performance degradation on both sides of the heat exchanger affects the optimal discharge pressure over the lifecycle. Proposing a mathematical correction method to adjust the initial discharge pressure and realize COP loss recovery from a control strategy perspective. The results demonstrate a gradual growth in the optimal discharge pressure, leading to a 15% additional COP loss after 10 years. The extent of heat transfer efficiency deterioration played a crucial role in determining the optimal discharge pressure deviation rate. Correcting the discharge pressure can minimize COP loss from a control strategy standpoint. Theoretically, under the specified test conditions, COP loss can be maximally recovered by approximately 2.48% (within 4 years) and 25.48% (within 10 years). This study contributes to the sustained reduction of electricity consumption in CO2 heat pump systems, thereby prolonging the energy-saving advantages of electric vehicles.