Prediction and Measurement of the Heat Transfer Coefficient in Direct, Oil-Cooled Batteries

Abstract

This paper presents an experimental measurement of the heat transfer coefficient (HTC) in a direct, oil-cooled lithium-ion battery at low Reynolds numbers. As demands on the electric vehicle battery pack increase, the role of thermal management to safeguard the pack becomes more important. Therefore, it is expected that various means for enhancing the HTC are sought. One way to increase the HTC is by shifting from air cooling to liquid cooling. The application of direct oil cooling in batteries has not yet been implemented. This paper explores this by developing the concept and an experimental steady-state technique to measure the HTC for direct oil cooling on a cylindrical 18650-cell battery at low Reynolds numbers. The experimental measurements are validated against known empirical correlations in the literature, showing that, despite the complex arrangement of cylindrical battery cells in packs, the classical correlations can be a useful tool to develop an oil-cooled battery thermal management system. A simplified correlation was also developed.