Experimental investigation on battery thermal management with ultra-thin vapor chamber

In electric vehicles, the chemical reactions occurring within the battery necessitate an efficient thermal management system to keep the battery within its optimal temperature range. Therefore, the development of a compact and effective thermal management system is essential. In this paper, a novel battery thermal management system based on ultra-thin vapor chambers with a thickness of 1 mm is proposed. To analyze the key parameters that affect the thermal performance of the battery thermal management system, an experimental system was established to investigate coolant flow rate, inlet coolant temperature, filling rate, and gravity conditions. Orthogonal design and fuzzy grey relational analysis were employed as evaluation methods. Orthogonal experiments can obtain a balanced sample of high precision with fewer trial runs, while fuzzy grey relational analysis is based on the measurement of similarity or dissimilarity between data sequences to explore the relationships among key system factors. The results show that the implemented battery management system achieves a reduction in maximum temperature by 23.2 %, 24.4 %, and 25.5 % under discharge rates of 1C, 1.5C, and 2C, respectively, while maintaining a temperature difference of less than 2 ℃. Even under conditions of high inlet coolant temperature of 30 ℃ and a discharge rate of 2C, the temperature difference remained below 2.28 ℃. Subsequently, the optimal filling rate is 120 %, and the maximum temperature of the battery pack is minimized with a temperature difference of less than 3 °C at this filling rate. Furthermore, considering the sensitivity evaluation, the discharge rate exhibited the most significant impact on both the maximum temperature and temperature difference, followed by the inlet coolant temperature and filling rate.