Numerical modeling of battery thermal management system with liquid cooling for electric vehicles

This study presents a comprehensive analysis of two advanced cooling methods immersion and bottom plate cooling applied to a cylindrical Lithium-ion battery cell (21700 format) for electric vehicles (EVs). Using 3D Computational Fluid Dynamics (CFD) simulations, the thermal performance of both methods was evaluated under various discharge rates (1C, 2C, and 3C) and coolant flow rates. The results demonstrate that immersion cooling offers significantly better thermal management than bottom plate cooling. Specifically, immersion cooling reduced the maximum cell temperature by 34%, maintaining a peak of 50.6 °C at a 3C discharge rate, whereas bottom plate cooling resulted in a peak temperature of 77.7 °C. Additionally, immersion cooling achieved a superior heat transfer coefficient of 225.08 W/m²K, compared to 193.49 W/m²K for bottom plate cooling. Immersion cooling also exhibited a more uniform temperature distribution, reducing temperature gradients and enhancing battery lifespan, especially at high discharge rates. At a lower discharge rate of 1C, the temperature difference between the two methods was minimized to 3 °C, indicating that bottom plate cooling remains effective under less demanding conditions. Furthermore, immersion cooling significantly reduced pressure drop by 59%, enabling more efficient coolant flow and lower energy consumption. The findings underscore the advantage of immersion cooling in high-performance applications, offering improved thermal control, energy efficiency, and operational safety