Design and optimization of heat pipe-assisted liquid cooling structure for power battery thermal management based on NSGA-II and entropy Weight-TOPSIS method

Abstract

The thermal management performance of Battery Thermal Management Systems (BTMS) is critical for the operational efficiency and lifespan of lithium-ion batteries (LIBs). Excessive temperature or excessive temperature differences within the battery pack can significantly affect both performance and longevity. To address the issue of excessive temperature differences caused by the installation of a single liquid cooling plate at the bottom, this study proposes a hybrid cooling structure combining heat pipes and liquid cooling plates. Through numerical simulations, the impact of coolant volume concentration and mass flow rate on BTMS cooling performance was analyzed. The results indicate that, compared to traditional single liquid cooling plates, the heat pipe-liquid cooling BTMS offers significant advantages in cooling performance. To further enhance the cooling efficiency of the BTMS, a single-factor analysis was conducted to investigate the effects of flow channel width (A), flow channel depth (B), liquid cooling plate wall thickness (C), and corner radius of the turn region (D) on the cooling performance of the battery pack. Subsequently, orthogonal experiments were performed to identify three structural factors with the greatest impact on the cooling performance of the liquid cooling plate, which were then selected as optimization design variables. A Kriging surrogate model was established between the design variables and objective functions (maximum temperature of the battery pack and flow channel pressure drop), and the NSGA-II genetic algorithm was employed to optimize the structural factors of the liquid cooling plate. To eliminate potential subjective bias in selecting the optimal solution, the entropy weight-TOPSIS method was introduced for the selection process. Simulation results demonstrate that, compared to the initial BTMS, the optimized BTMS reduces the maximum temperature, temperature difference, and flow channel pressure drop of the battery pack by 2.29%, 6.02%, and 79.62%, respectively. The optimized BTMS significantly improves the operational performance of the battery pack while achieving exceptional cooling effects under low power consumption. The results of this study provide valuable theoretical and practical insights for the design and optimization of the Heat pipe liquid-phase hybrid cooling structure.