Numerical analysis of temperature uniformity of a liquid cooling battery module composed of heat-conducting blocks with gradient contact surface angles

Battery thermal management has an important significance for electronic vehicles to maintain a suitable temperature range and reduce local temperature differences. In this study, a novel liquid cooling battery thermal management system (BTMS) that uses a straight microchannel flat tube and heat-conducting blocks with gradient contact surface angles is proposed to improve the temperature uniformity of cylindrical lithium-ion battery module. A three-dimensional transient heat transfer model is conducted to investigate the thermal performance of the proposed battery module with 48 cells arranged on both sides of a straight microchannel flat tube. The effects of contact surface angle (alpha(i)), gradient angle increment (Delta alpha) and inlet velocity of the fluid medium on the cooling performance are discussed. The results indicated that the module with a gradient contact surface angle, which implies gradually increasing the heat transfer area, further improved the temperature uniformity of the battery module compared to that with an unchanged alpha(i). In addition, the increase of the inlet velocity does have a positive effect on both the reduction of maximum temperatures and enhancement of uniform temperature distribution. When Delta alpha is 15 degrees and the inlet velocity of the fluid medium is 0.015 m/s, the temperature difference (Delta T) of the battery module can reach 2.58 degrees C at the end of discharge. In addition, the preheating performance of the battery module at subzero temperature is also discussed. The results show that the temperature uniformity increase with the increase of the gradient angle, thus when Delta alpha is 15 degrees, the temperature difference of the battery module can be controlled to 8.05 degrees C.