Optimization and thermal performance analysis of direct cooling plates with multi-splitting-merging channels for electric-vehicle battery thermal management

The multi-channel battery thermal management system (BTMS) based on refrigerant direct cooling has the characteristics of high cooling efficiency and excellent temperature uniformity. It is expected to alleviate the problems of a large amount of heat generation and excessively high local temperature of lithium-ion batteries in electric vehicles during the rapid charge and discharge process. In practical applications, the cooling effect of the direct cooling method is closely related to the dimension and distribution of the mini-channels on the direct cooling plate (DCP). However, the large number of mini-channels and their intricate dimension and distribution pose challenges to both experimental research and numerical modeling. Therefore, in order to analyze the heat transfer performance of the large-format and multi-splitting-merging DCP, this study firstly integrated the correlation algorithm and the tensor operator to establish a novel model of two-phase refrigerant heat transfer. After comparison with the experimental results, this study analyzed the causes of local overheating of a mass-produced DCP. To eliminate the overheated zone, this study proposed an optimization criteria on the dimension and distribution of the mini-channels of DCP. After optimization, the maximum temperature of the DCP is reduced from 42 °C to 31 °C, the maximum temperature difference is less than 5 °C, and the pressure drop of the DCP is reduced from 95 kPa to 72 kPa. The optimized DCP could increase the charge/discharge cycle life of lithium-ion batteries by 30.7 %, and reduce the energy consumption of the compressor by 6.4 % in comparison with the mass-produced DCP. These results can potentially provide a promising thermal management solution for lithium-ion batteries.