Ultra-thin minichannel LCP for EV battery thermal management

摘要

The development of electric vehicles (EVs) demands for complementary technologies in battery thermal management. To achieve fast charging/discharging capacity, liquid cooling is an effective means of maintaining temperature of a battery in operation within a narrow optimal range. In conventional straight channels, convective heat transfer deteriorates along the axial direction with the development of the hydrodynamic boundary layer, resulting in elevated maximum temperature and significant temperature gradient in the fully developed region. This is a serious problem as temperature uniformity is of utmost importance to the performance and lifespan of a Li-ion battery. In this research, a simple configuration of oblique cuts across the straight fins of a conventional straight channel design was developed, to enhance the performance of the conventional channel with minimal pressure penalty. These oblique cuts across the straight fins form an oblique fin array. The designed liquid cold plate (LCP) contains these simple oblique fins with optimized angle and width. This segmentation of the continuous fin into oblique sections leads to the re-initialization of boundary layers, providing a solution to the elevated temperatures caused by a thick boundary layer in the fully developed region. Experimental results show that heat transfer coefficients of oblique minichannel are higher than those of conventional straight minichannel. The oblique LCP is able to maintain the battery surface average temperature below 50 ℃ for a heat load of 1240 W at a flow rate lower than 0.9 l/min. This implies that a proper designed minichannel cold plate could be a promising solution for EV battery thermal management.