Emergence of elevated battery positioning in air cooled battery packs for temperature uniformity in ultra-fast dis/charging applications

Abstract

Pure electric vehicles (EVs) are gradually becoming major interest of research in worldwide. Battery cells in EV battery packs must be kept in between the desired operational temperature range (similar to 30 degrees C) and temperature should be homogeneous in packs to eliminate safety risks and prolong battery life. In this study, performance of a novel BTMS design was studied at various discharge conditions with fast and ultra-fast C-rate values. Cooling with natural convection exceeds desired operational temperature in the pack as well as forced air convection in Z-type manifold. Elevated battery positions yield flow resistance along the air channels in between battery cells to be uniform which yields flow rate sweeping the surface of each cell to be the same. Therefore, the maximum temperature in between cells decreases to less than 0.3K from the order of 12K. The temperature uniformity is essential for ageing and electrical resistance of cells to be homogeneous in a pack. In addition, heat transfer enhancement with various fin designs is documented as well as its effect on the temperature distribution. The accuracy of numerical studies is validated by experimental work. The results show that the peak temperature can be kept under the desired operational temperature with minimum deviation in the temperature difference for distinct operation conditions required for advanced electric vehicles (cars, airplanes, helicopters) with extreme charging and discharging capability.