Development and modeling of novel battery thermal management systems for electric and hybrid electric vehicles

Abstract

Thermal management system is necessary to control the operating temperature of the lithium ion batteries in battery packs for electrical and hybrid electrical vehicles. This thesis studies, develops and models novel battery thermal management systems for the battery packs in hybrid electric vehicles and electric vehicles. The systems’ thermal performances are assessed through thermal and electrochemical models. The performances of the proposed systems are investigated in terms of various performance measures including the maximum temperature in the pack and the temperature distribution throughout the battery pack and through each battery. The results show that pool based systems achieve better performance for cylindrical battery packs than for prismatic battery packs. For a pool system, covering 30% of the battery height reduces the maximum battery temperature by 28% to 40% depending on the fuel type for a high intensity cycle. To achieve 28% to 40% reduction in the prismatic battery maximum temperature from the case where there is no cooling, the pool system has to cover 80% of the battery height. The best performing system for prismatic battery packs is the tube based system, where the aluminum cold plate has tubes completely filled with coolant to maintain the battery temperature within range needed for the best performance possible by the system. The tube cold plate based system maintains 80% less coolant in the battery pack at a time than the direct contact pool based system while achieving a higher performance in terms of the maximum battery temperature and the maximum temperature difference across the battery pack. The response time for the proposed systems reached nearly 10 times faster than liquid and air systems proposed in the literature. Compared with the literature the pool based system response was 1.7% of the cycle time compared to around 17% for the cycle time for the mini channel cold plate cooling system.