Optimization of three-layer staggered liquid cooling system for high-rate charging of large cylindrical battery module in electric vehicles

Efficient thermal management is essential for ensuring the safety and reliability of large cylindrical lithium-ion battery modules under ultra-fast charging. This study proposes a three-layer staggered liquid-cooled pipe (TSLP) design for a 37-cell (32700) module and evaluates its performance through combined computational fluid dynamics (CFD) simulation, experimental validation, and Box-Behnken design (BBD) optimization. Parametric analyses reveal that a staggered counter-flow layout with a middle-layer pipe height of 34 mm and wall thickness of 0.6 mm achieves favorable temperature control, with a peak module temperature of 36.17 °C and a maximum inter-cell temperature difference of 2.43 °C. A BBD response surface methodology was employed to optimize operating conditions, including inlet flow rate, ambient temperature, and coolant precooling rate. The optimal solutions at ambient temperatures of 35/40/45 °C correspond to inlet velocities of approximately 0.044/0.047/0.049 m/s and precooling rates of 3.6–3.9 °C/min. Validation shows high consistency between experimental data, CFD simulations, and BBD predictions, with deviations below 0.4 °C. These results demonstrate that the TSLP system offers improved cooling uniformity and scalability for large-format cylindrical cells, providing practical guidance for high-power battery thermal management in electric vehicles.