Improvement of Homogeneity for Direct Cooling Battery Thermal Management System in Electric Vehicles under Dynamic Operating Conditions
Lithium-ion batteries are widely used in electric vehicles due to their high energy density, long cycle life, and stability. However, significant heat generation caused by power fluctuations under dynamic driving conditions poses substantial challenges to battery safety and longevity. Existing research often focuses on thermal behavior under fixed ambient temperatures or constant discharge rates, failing to replicate real-world dynamic operations. This study investigates the thermal performance of a 52 Ah battery pack under three typical dynamic operating conditions: steady operation, alternating load operation, and progressive acceleration. Experiments were conducted at ambient temperatures of 25, 30, and 35°C. Results show that the direct cooling thermal management system meets temperature control requirements during steady and alternating load operations at all tested temperatures. However, under progressive acceleration at 35°C, the battery pack's maximum surface temperature reaches 49.8°C with a significant temperature difference of 16.5°C, exceeding safe limits. After installing aluminum fins, the maximum temperature is reduced to 40.9°C, and the temperature difference drops to 5.0°C. Longitudinal temperature difference decreases from 11.2°C to 4.6°C, and transverse temperature difference from 5.9°C to 1.2°C. The fins enhance longitudinal heat conduction and mitigate transverse temperature imbalance. These findings underscore the importance of optimizing thermal management strategies and provide experimental data for developing more effective systems, contributing to improved battery safety and longevity under real-world driving conditions.