Experimental and numerical analysis of a liquid-air hybrid system for advanced battery thermal management

Abstract

Abstract This study introduces an innovative hybrid Battery Thermal Management System (BTMS) that combines air and liquid cooling mechanisms for optimal thermal control in small-scale EV applications. Recognizing the limitations of the existing single-method cooling systems, we developed a novel Hybrid Battery Thermal Management System that combines air and liquid cooling to provide superior temperature management. Additionally, we performed a detailed experimental evaluation to verify the accuracy of our heat generation model for lithium-ion batteries. This included the construction and testing of the proposed hybrid cooling system in a controlled environment using a climate chamber that simulated various ambient temperatures. We assessed the system performance under different operational stresses, specifically at 1C and 2C discharge rates. The tests encompassed a range of temperatures, starting at a standard room temperature (20 °C) and increasing through three levels of ambient temperature: 30, 35, and 40 °C. Initial tests under natural convection conditions showed a non-uniform temperature distribution and temperatures near the upper safety limits, with a maximum of 51 °C. While the addition of an air-cooling system provided some improvement, it still resulted in localized hotspots. However, the hybrid battery thermal management system effectively addressed these challenges, achieving marked improvements in cooling efficiency and temperature uniformity, yielding a 21.04 % improvement in cooling by reducing the maximum temperature at 2C from 51.2 °C (no cooling) to 40.9 °C while also improving the uniformity of the temperature distribution among the packs. Further tests at elevated ambient temperatures confirmed the robustness and adaptability of this system. These findings highlight the scalability of the system and suggest its potential applicability to larger battery systems, opening avenues for future research and practical implementation.

Keywords: Hybrid cooling system ,Air cooling, Liquid cooling, Lithium-ion batteries, Thermal control