Framework for rapid design and optimisation of immersive battery cooling system

Effective battery thermal management system (BTMS) is critical for lithium-ion battery (LIB) safety and performance in electric vehicles. This study presents a CFD-driven optimisation framework for an immersion cooling BTMS using sustainable palm biodiesel as coolant. A conjugate heat transfer model for a 3S2P pouch cell module (20 Ah LiFePO₄) is developed and validated against experimental data (<2% error). The CFD model of a battery module is developed to train an ultra-fast metamodel for battery geometry optimisation. Two key parameters are optimised, namely: battery gap spacing (3-10 mm) and inlet/outlet width (5-15 mm), via Optimal Latin Hypercube Sampling, Support Vector Regression, and GDE3 genetic algorithm. Palm biodiesel is used as a dielectric coolant in the proposed system to preserve LIB temperature within 20-40 , preventing thermal runaway and ensuring a lightweight BTMS design. Compared to a conventional 3M-Novec, the palm biodiesel achieved system lightweight by 43%. The findings can establish biofuel immersion cooling as an eco-friendly BTMS solution, achieving Pareto-optimal figures: T _max < 29.9°C, Δ T < 5°C, and Δ P < 145.275 Pa (at 5C and 0.05 m/s).