Numerical Investigation of a Hybrid Phase Change Material–Heat Pipe Battery Thermal Management System for Enhanced Thermal Regulation under High Discharge Conditions

This study presents a numerical investigation of a hybrid battery thermal management system (BTMS) that integrates phase change material (PCM) and heat pipes (HP) to control the thermal behavior of lithium‐ion batteries under varying discharge rates and thermal boundary conditions. The model is validated against experimental and published numerical results, achieving a temperature deviation within ±1.2% and a root mean square error below 1.5 K. Simulations of bare batteries reveal critical temperature rise above 345 K at a 4 C discharge rate under low convective cooling (heat transfer coefficient, HTC = 15 W m⁻² K⁻¹), risking thermal runaway. The use of PCM alone reduces peak temperature by 10–12 °C, while PCM combined with HP enhances thermal regulation, reducing maximum temperature by an additional 3–4 °C and improving surface temperature uniformity (ΔT reduction up to 2 K). At HTC = 60 W m⁻² K⁻¹, further temperature reductions of 6–8 °C are observed, with improved PCM re‐solidification. The hybrid BTMS maintains battery temperatures below 324 K and ΔT < 5 K under extreme loading. These results confirm that PCM + HP systems significantly enhance thermal safety, uniformity, and performance, offering a viable thermal solution for electric vehicle and grid‐scale energy storage systems.