Effects of module size on the heat dissipation performance of the thermal management system for the battery module with cylindrical cells

Heat dissipation performances of battery thermal management systems (BTMSs) reported in the literature are usually evaluated based on the modules with different sizes. Yet, effects of module size on the cooling performance of liquid-cooling BTMS with mini-channel cold plates are still unclear, which makes the performance comparisons of BTMSs from different researches difficult. In this context, systematic numerical investigations are conducted in this work to analyze the thermal performances of cylindrical battery modules with rectangular array structures ranging from 4 x 8 to 4 x 16, 4 x 32 and 4 x 48. The results demonstrate that increased module size is unfavorable to the heat dissipation performance of BTMS, especially in terms of temperature uniformity. To ameliorate the heat dissipation performance of BTMS, extended studies are performed to analyze the thermal behaviors of BTMSs with different module sizes under various coolant velocities and flow direction arrangements. Special attention is paid to their cooling performances under low coolant velocities, which are commonly ignored in previous studies. Based on the results, merits and demerits of different optimization methods are elucidated via in-depth mechanism analyses. Importantly, ultra-low velocity (0.0025 m s-1 in this work) operation is found a promising method to ease the contradiction between the cooling performance and the increased energy consumption owing to the dramatically enhanced temperature uniformity. The results could provide useful guidance for the future design of BTMS in the cylindrical battery module.