Enhancing the cooling efficiency of the air cooling system for electric vehicle battery modules through liquid spray integration

Abstract

To achieve the desired voltage and power capacity to serve as the primary power source in electric vehicles (EVs), the battery cells are densely interconnected in both series and parallel configurations, forming modules. These modules are further assembled to create the pack. Excessive heat generated by chemical reactions and internal resistance can lead to reduced capacity, instability, and thermal runaway. Hence, the implementation of a battery thermal management system is crucial to maintain the batteries operating within the optimal temperature range. In this study, a novel cooling system was proposed that combines an integrated non-electrically conductive liquid spray called hydrofluoroether (HFE) with forced air as the cooling fluids. A three-dimensional transient heat transfer model for the cylindrical lithium-ion battery module was developed by using ANSYS Fluent. Numerical investigations were conducted to evaluate the impact of liquid injection rate and injector arrangement on the cooling performance of the battery module. The findings demonstrate that the proposed technique effectively decreases the maximum temperature and the unbalanced temperature difference within the battery module compared to the traditional method of dry air cooling. The optimized system, which entails placing the nozzles between rows 1 and 2 of the battery module and maintaining a consistent mass flow rate of 20 g/s, leads to a decrease in the maximum temperature and temperature nonuniformity by about 6 °C and 4 °C, respectively. These insights provide valuable guidance for the design of spray-assisted forced-air cooling systems and contribute to the development of efficient thermal management solutions for EVs.