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

Anair cooling battery thermal management system (BTMS) is widelyused in electric vehicles (EVs). In this work, numerical simulationis used to provide a greater understanding of the system efficiencyof T-type symmetric air cooling BTMS (T-BTMS) and its coupled systems.For T-BTMS, the method of the coefficient of variation (MCV) is appliedto evaluate the schemes with different inlet flow rates and batteryclearances. It is found that optimum cooling performance and energyconsumption are achieved at an internal clearance of 3 mm and an inletair velocity of 6 m center dot s(-1). Further improvementsin cooling performance can be realized by introducing heat transferfins into the module. Increasing the number of fins can improve coolingperformance but results in higher energy consumption. To further improvethe cooling performance at high battery discharge rates, a coupledsystem with air cooling and liquid cooling is proposed. It is foundthat, at high discharge rates, the coupled system gives better coolingperformance and lower energy consumption compared to uncoupled systems.When the battery module is fully discharged at the rate of 4 C, themaximum temperature of the coupled system is below the critical valueof 45 degrees C and the maximum temperature difference is less than5 degrees C.