A study of variable cell spacings to the heat transfer efficiency of air-cooling battery thermal management system

The air-cooling battery thermal management system has been widely adopted as the thermal management device for power accumulators on electric vehicles nowadays. To improve the system heat transfer coefficient with the minimum rise in cost, this study modified conventional rectangular cell arrangements for 21,700 cylindrical cell battery packs with two approaches: 1. increase the vertical spacings; 2. convert constant vertical spacings to gradient vertical spacings. The results show that smaller vertical spacings are beneficial to the overall cooling performances of the constant vertical spacings designs at almost all flow rates. The gradient vertical spacing design with larger spacing could deliver better temperature uniformity, while the one with smaller spacings could suppress the maximum temperature more efficiently at higher flow rates. However, the total battery pack volume of Design 7 (the largest gradient vertical spacing design) is 7.5% larger than the conventional design.