Performance analysis of an air-cooled battery thermal management system with inclined baffles

The performance, safety and service life of lithium-ion batteries are greatly affected by the operating temperature and temperature uniformity. Hence, an efficient battery thermal management system is essential to control the temperature increase and reduce the thermal non-uniformity in densely packed battery modules. This work investigates an air-cooled battery thermal management system with inclined aluminum baffles for a 5 × 5 pack of 18,650 cylindrical cells. Thermal and hydraulic performance are systematically evaluated according to the baffle geometry, inclination angle and airflow conditions. Eight configurations (case-C1 to case-C8) with a bare-pack baseline are studied at Reynolds numbers of 3032–7580 with baffle inclinations of 30° and 45°. The results show that the 45° inclined configuration (case-C5) provides the most favorable thermal performance, consistently producing higher Nusselt numbers and reducing ΔT by about 5–6 K, while keeping T max near 335 K. With an increase in baffle length, thermal enhancement increases up to L/D = 0.11, beyond which further improvement is limited due to increased flow resistance and flow bypassing. To enable fast thermo-hydraulic prediction, an XGBoost surrogate model was built based on the computational fluid dynamics dataset. The model achieved the testing R ² value of 0.9934 for friction factor and 0.9937 for the Nusselt number with a root mean square error of 0.0226 and 0.8503, respectively. These results show the potential of optimized baffle geometry to improve air-side battery cooling, with the associated hydraulic penalty considered, and the developed XGBoost framework offers an efficient approach for surrogate-based thermo-hydraulic prediction and future design optimization.