Improving Thermal Uniformity in Li-Ion Battery Packs Using Fin-Enhanced Dielectric Immersion Cooling Technique

This study investigates the thermal management performance of a 4S2P lithium-ion battery pack immersed in a dielectric fluid under three distinct flow-field configurations: no fins, circular fins, and triangular fins. A multiphysics simulation framework using ansys fluent was implemented to model fluid flow and heat transfer, with a focus on achieving optimal cooling efficiency and thermal uniformity. The designs were evaluated across multiple volumetric flowrates to determine the conditions required to maintain the optimal pack temperature near 30 °C from the ambient (25 °C). Results indicate that the triangular-fin configuration achieved the optimal battery pack temperature at a comparatively lower flowrate of 5 LPM and pressure drop of 289 Pa, outperforming both the circular-fin and no-fin configurations. Furthermore, the triangular fins produced the most uniform temperature distribution, as evidenced by the lowest thermal gradient of 2.0 °C, compared to circular fins and no-fin configuration. Velocity streamline visualizations confirmed superior coolant dispersion in the triangular-fin design, minimizing stagnant zones and enhancing convective heat transfer. The findings demonstrate that triangular fins offer an optimal trade-off between flowrate efficiency and thermal performance, making them the most effective among the tested configurations for immersion-cooled battery packs.