Investigation of the thermal performance and heat transfer characteristics of the lithium-ion battery module based on an oil-immersed cooling structure

Abstract

Based on the concept of direct contact liquid cooling, a compact oil-immersed battery thermal management system is designed in this work. In the experiment, methyl silicone oil, white oil, and transformer oil are used as coolants to study the cooling effect and the heat transfer characteristics of the system. It is found that three oils show good cooling effects and temperature uniformity in general at three discharge rates. The maximum average temperatures of the battery module immersed in silicon oil, white oil, and transformer oil reach 53 °C, 47.3 °C, and 45.6 °C, respectively, under the maximum discharge condition (2 C). It decreases by about 25 %, 33 %, and 35 % compared with the maximum temperature of the battery module under natural convection cooling (70.5 °C). In addition, the theoretical analysis verifies that the battery heat production and the ratio of heat absorbed by three oils to the total heat production increases with the discharge rate. At the end of 2 C discharge, the ratio of heat absorbed by silicone oil, white oil, and transformer oil to the total heat production reaches 38.9 %, 46.3 %, and 49.5 %, respectively. Theoretical calculations show that all three oils can effectively absorb the heat generated by the battery, and especially transformer oil can achieve an excellent cooling effect. The results further confirm the effectiveness of the oil-immersed battery thermal management system, which provides additional new insights for the future development of battery thermal management systems based on immersion cooling.