Numerical study of a hybrid battery thermal management system for enhanced thermal regulation in electric vehicles

This study numerically investigates the thermal performance of a three-dimensional battery thermal management system (BTMS) incorporating a rectangular cooling plate with a serpentine channel. The current study mainly focuses on cooling the positive and negative terminals of batteries in a module using air and liquid cooling strategies under varying discharge rates (0.7C, 1C, and 1.5C), cooling plate configurations, and fluid velocities. A Newman P2D electrochemical-thermal model is employed to simulate thermal energy generation and is coupled with fluid flow and heat transfer models to ensure mass, momentum, and energy conservation. The results indicate that increasing air velocity to 5 ms(-1) in air-cooled BTMS reduces T-max by 9.75 K, 10.21 K, and 9.73 K for 0.7C, 1C, and 1.5C discharge rates, respectively, with minimal reduction beyond this velocity, establishing 5 ms(-1) as optimal. Further, incorporating two cooling plates reduces T-max to 304.42 K and Delta T to 3.15 K at 0.7C, while three cooling plates achieve T-max of 305.40 K and Delta T of 3.89 K at 1C, demonstrating optimal designs for this discharge rates. At 1.5C discharge rate, the hybrid BTMS with three cooling plates, with a water velocity of 0.10 ms(-1), lowers T-max to 305.69 K and Delta T to 4.43 K, achieving optimal cooling. Compared to air-cooled BTMS, hybrid BTMS with a rectangular cooling plate reduces T-max by 7.03%, 8.73%, and 11.41% for 0.7C, 1C, and 1.5C, respectively, maintaining battery temperatures below operating limit (308.15 K) with Delta T < 5 K, ensuring thermal uniformity.