Numerical Study on the Influence of Key Factors on the Immersion Thermal Management System of an Electric Vehicle Power Battery Pack

With increasing demand for electric vehicles, the safety and performance of their power batteries have presently become one of the most pressing issues. Immersion thermal management systems have become the focus of next-generation technology due to their direct contact, high specific heat capacity, and excellent temperature uniformity. This study analyzed the influence of mass flow rate, battery spacing, and inlet and outlet layout on single-phase immersion thermal management systems. The mass flow rate was varied to obtain the quantitative results of the maximum temperature, minimum temperature, and temperature difference of the battery pack over time. The battery spacing was changed to analyze its influence on battery temperature distribution in combination with the temperature cloud graph. Four inlet and outlet layout schemes were designed. A velocity vector diagram was used to reveal the structural differences of the flow field inside the box, and the temperature uniformity index was used to evaluate the potential optimization direction. The results show that an increase in mass flow rate can enhance the heat dissipation effect of the immersion thermal management system and decrease the maximum temperature of the battery pack 5.21%. When the battery spacing is increased within a limited range, the temperature of each individual battery decreases accordingly, with a maximum reduction of 3.58%. In addition, the temperature uniformity of the battery does not change significantly. When the inlet and outlet are arranged from top to bottom (Case 2), the battery pack has the best temperature uniformity, with only a 0.62°C difference, a reduction of 36.73%.