A novel electric vehicle thermal management system based on cooling and heating of batteries by refrigerant

A refrigerant-based thermal management system (TMS) for electric vehicles (EVs) is proposed and analyzed, aiming to tackle the conflict between the cabin thermal comfort and the battery thermal safety, and to realize the battery heating or cooling directly by the refrigerant without supplementary devices. Compared with the traditional EV TMSs, an electronic expansion valve (EEV) is equipped after the battery cooling/heating device in the refrigerant branch circuit. The performance of the proposed new TMS is investigated by mathematical simulations in conditions of the standardized New European Driving Cycles (NEDC) and different climates. The simulation results indicate that both the temperatures of the cabin air and the battery pack can be well controlled by the proposed TMS. In the cabin-and-battery mixed cooling mode for summer, the cooling temperatures for the cabin and the battery can be adjusted independently, and the cabin air can be cooled to the target temperature effectively as well as the battery thermal safety is guaranteed. In the cabin-and-battery mixed heating mode for winter, the high temperature refrigerant flows through the battery cooling plate and heats the batteries with the latent heat of condensation, and the battery preheating can be completed within 15 min and 9 min in the condition of 0 °C and 7 °C ambient temperature, respectively. Besides the thermal behaviors of the cabin and the battery, the controls of the compressor and the valves are also investigated to verify the practical feasibility of the proposed TMS.