Design and Optimization of Converging-Diverging Liquid Cooling Channels for Enhanced Thermal Management in Lithium-ion Battery Packs

Power batteries serve as key components of new energy vehicles and are distinguished by their large capacity, long lifespan, high energy density, and stable operation. The strict temperature demands of power battery packs necessitate the development of highly efficient thermal management systems. In this study, a converging-diverging liquid cooling channel featuring a wave shaped structure was designed and analyzed for 18,650-type lithium-ion batteries. To investigate the design methodology for flow channel structure, a thermal model for the heat generation rate of the 18,650-type battery was developed. A comparative analysis of four geometrical configurations of converging-diverging channels. It identified the flat-bottomed channel achieves a maximum reduction of 20.6% in peak internal temperature compared to the other designs. Subsequently, the effects of the arc depth, cell spacing, and Reynolds number on the heat dissipation of the flat-bottomed flow channel were comprehensively investigated. The results demonstrated that increasing the Reynolds number, maximizing the arc depth of the converging-diverging structure, and reducing cell spacing considerably improved the cooling heat dissipation efficiency. Based on the particle swarm optimization algorithm, the optimal parameter combination of the battery pack was obtained at a discharge rate of 2C, comprising an arc depth of 8.5 mm, cell spacing of 1 mm, and Reynolds number of 700. The study provides valuable guidance and references for the practical design and implementation of thermal management systems in new energy vehicles.