Numerical investigation and structural optimization of a battery thermal management system based on refrigerant evaporation

An efficient battery thermal management system is essential for ensuring the safety and stability of lithium-ion batteries in electric vehicles (EVs). As a novel battery thermal management system (BTMS), refrigerant evaporation cooling has been widely studied due to superior heat transfer efficiency and more compact circuit design. A comprehensive understanding of the operating conditions and structural parameters is essential for system performance. In this study, a refrigerant evaporative cooling system option was proposed and analyzed. A thermal model of lithium-ion batteries was developed and validated experimentally. The impact of different operating conditions on the thermal and power consumption performance was analyzed. Based on traditional cold plates, several novel designs were proposed and compared to improve performance. The system's effectiveness at high discharge rates is validated by flow rate matching. The results showed that the inlet velocity had a more significant impact on the thermal and power consumption performance than the inlet gas-phase volume fraction and saturated evaporation temperature. Besides, the proposed design can reduce the maximum temperature from 34.24 to 28.91 °C and the temperature difference from 5.7 to 2.4 °C at 1C discharge rate. Moreover, the thermal performance can be ensured under 3C discharge rate. This study is helpful for the development of BTMS based on refrigerant evaporative cooling in EVs.