Numerical Optimization of a Hybrid Cooling System for Lithium‐Ion Battery Packs: PCM‐Assisted and Liquid Cooling Integration

ABSTRACT This study proposes a hybrid cooling system design that constructs a phase change material (PCM) filled layer between a liquid cooling jacket and cylindrical battery cells, combining the advantages of efficient liquid cooling and passive temperature control from PCM. The system performance was optimized through numerical simulation. First, cooling effects and pressure drop characteristics of different channel shapes were compared. Subsequently, single‐factor analysis was used to investigate the effects of PCM thickness, contact angle/height, Reynolds number (Re), and coolant initial temperature on system performance. Multi‐objective optimization was conducted using orthogonal experimental design. Results show that increasing Re has limited improvement in the cooling performance. The optimal parameter combination is a PCM thickness of 4 mm, contact angle of 180°, contact height of 14 mm, and coolant initial temperature of 15°C. Compared with the initial structure, the optimized system reduces the maximum temperature by 6.44%, the maximum temperature difference by 7.34%, and the PCM liquid‐phase fraction by 63%. Optimizing the coolant flow direction further controls the maximum temperature of the battery pack below 34.88°C and reduces the maximum temperature difference to 3.69°C, a 4.69°C decrease compared with the pure liquid cooling system. The liquid fraction of PCM in the optimized hybrid cooling model is as low as 23.37%, which greatly reduces the risk of leakage and can promote the development of sustainable energy storage technologies.