Improving the air-cooling performance for lithium-ion battery packs by changing the air flow pattern

Abstract

Air-cooling battery thermal management system (BTMS) is commonly used to maintain the performance and safety of lithium-ion battery packs in electric vehicles. In this paper, based on the conventional Z-type and U-type flow BTMSs, several novel BTMSs with different flow patterns are designed on the 4 × 9 21700 battery module by changing the outlet positions, and the performance of these BTMSs are evaluated with numerical simulations. The results show that the flow pattern of the air-cooling BTMSs has a significant influence on the BTMS cooling performance. When the outlet is located at the top of the battery module and the center plane of the outlet is closer to the inlet, the BTMS reveals a better cooling performance. In this system, when the inlet wind speed reaches 5 m/s, the average temperature and maximum temperature of the battery packs both reduce about 3 °C, with the Z-type BTMS flow pattern. Meanwhile, the temperature uniformity of the battery packs is greatly improved. Comparing with the U-type flow pattern, the average and the maximum temperatures reduce about 0.8 °C and 2.4 °C, respectively. The numerical simulations also demonstrate that with the increase of the inlet wind speed, the flow pattern of the BTMS has a significant effect on the cooling performance.