Numerical Investigation of Phase Change Material Effects on Battery Cooling in Microgravity

Efficient thermal management is vital for lithium-ion batteries to ensure safety, reliability, and performance in electric vehicles. This study investigates passive cooling using phase change materials (PCMs) in a computationally complex scenario. Three PCMs (RT31, RT35, and RT38) were analyzed at three thickness levels (PCM_T1, PCM_T2, and PCM_T3) to evaluate their effects on battery surface temperature, melting behavior, and thermal energy storage. The best-performing PCM and thickness combination was further analyzed under Earth gravity, moon gravity, and microgravity conditions to examine the effect of gravity on the melting behavior and thermal performance of the optimized battery thermal management system configuration. Simulations employed the enthalpy–porosity method to model solid-to-liquid phase transitions while accounting for heat generation at a 3C discharge rate. Results show that both PCM type and thickness strongly affect cooling efficiency. RT31 offered the highest energy storage but led to elevated surface temperatures due to heat retention, while RT38 showed moderate cooling with delayed melting. RT35 at PCM_T1 achieved the lowest surface temperature (307.29 K) and minimal temperature difference (7.29 K), demonstrating the most balanced thermal behavior. Reduced gravity significantly prolonged melting time sixfold on the moon and slightly more under microgravity, highlighting the importance of gravity in PCM performance.