Perforated Plate and Deflector Integration Enhance Cooling Performance of Immersed Lithium Battery Pack

Lithium-ion batteries, owing to their high energy density and superior power characteristics, serve as a critical component for ensuring the stable and continuous operation of power systems. However, their high energy density and fast charge–discharge capability also lead to significant heat accumulation within battery packs. To address this issue, this study investigates the thermal management of a lithium battery pack using a novel direct-immersion liquid cooling structure through comsol multiphysics simulations. The cooling performance and temperature uniformity are enhanced by optimizing the coolant flow channel geometry and adjusting operating conditions. Model validation confirms the reliability of the simulation results. The effects of coolant inlet velocity, outlet position, coolant type, and deflector angle on the temperature and flow fields within the pack are systematically examined. Simulation results show that a coolant velocity of 4–5 m/s yields optimal cooling performance. The outlet placement along the positive x-axis or negative y-axis leads to better temperature uniformity compared to placement along the negative x-axis or positive y-axis. Low-viscosity coolants achieve more uniform coverage of the cooling region, while water-based fluid, combining high thermal conductivity with relatively low viscosity, provides the most favorable temperature distribution. Adjusting the deflector angle has a comparatively smaller influence on thermal behavior than varying the flow velocity, outlet position, or coolant type. The findings of this work provide a robust database for the design of immersed lithium-ion battery packs.