Optimization of the Cooling Performance of Symmetric Battery Thermal Management Systems at High Discharge Rates

Abstract

An air cooling battery thermal management system (BTMS) is widely used in electric vehicles (EVs). In this work, numerical simulation is used to provide a greater understanding of the system efficiency of T-type symmetric air cooling BTMS (T-BTMS) and its coupled systems. For T-BTMS, the method of the coefficient of variation (MCV) is applied to evaluate the schemes with different inlet flow rates and battery clearances. It is found that optimum cooling performance and energy consumption are achieved at an internal clearance of 3 mm and an inlet air velocity of 6 m·s–1. Further improvements in cooling performance can be realized by introducing heat transfer fins into the module. Increasing the number of fins can improve cooling performance but results in higher energy consumption. To further improve the cooling performance at high battery discharge rates, a coupled system with air cooling and liquid cooling is proposed. It is found that, at high discharge rates, the coupled system gives better cooling performance and lower energy consumption compared to uncoupled systems. When the battery module is fully discharged at the rate of 4 C, the maximum temperature of the coupled system is below the critical value of 45 °C and the maximum temperature difference is less than 5 °C.