Investigation of the Cooling Characteristics of Hybrid Liquid Spray and Air Cooling for an EV Battery Pack

In an electric vehicle, battery thermal management system plays a critical role in the maintaining optimal temperatures inside the battery pack to extend its lifespan, improve its performance along with the operational safety. Several attempts have been made to achieve the practical and efficient systems of battery thermal management. The contribution of previous research on this topic has received little attention on the evaporative cooling to dissipate excess heat from the battery pack during charging and discharge cycles. This study focuses on investigating the cooling performance of a battery thermal management system in an electric vehicle that uses forced-air cooling along with a non-electrically conductive liquid spray. The liquid spray used in the simulation was the hydrofluoroether (HFE) Novec-7100 fluid developed by 3M. The study consisted of simulations that evaluated the impact of the fluid injection rate on the heat removal performance of a 40-cell cylindrical lithium-ion battery pack. The results showed that using the HFE liquid spray was effective in reducing the maximum temperature and improving the temperature uniformity compared to using only air cooling. However, the cooling performance weakened as the flow rate of HFE increased. The optimal flow rate of HFE should be determined for effective thermal management of the densely-packed batteries.