Enhancing thermal management in cylindrical Li-ion battery through PCM integration with variable contact area

Abstract

Cylindrical Li-ion batteries are widely embraced in various sectors, notably electric vehicles and renewable energy storage systems. An effective thermal management system is vital for their safe and dependable operation, enhancing both the performance and reliability of the system. This study employs a distinctive hybrid cooling strategy consisting of a phase change material (PCM) at the centre of the battery and liquid cooling at the surface of the cylindrical batteries. The contact area between the coolant and the battery’s surfaces varies to make sure same heat transfers from each battery. This approach is instrumental in maintaining thermal uniformity and regulating the maximum temperature. In the numerical analysis, we employed ANSYS Fluent 2022 R1 to create the computational model encompassing the Li-ion battery, PCM, and liquid cooling system. This arrangement utilized eight 18650Li-ion batteries, with each battery housing a 2 mm radius PCM rod at the centre of the batteries. A heat-conducting element (HCE) was introduced to facilitate contact between the battery and the coolant channel. Water was selected as the coolant, and the coolant channel cross-sectional area is 65 × 2 mm2. The relationship governing the variable contact area is determined by fixing the velocity and the first battery contact area. The variable contact geometry maintains thermal uniformity throughout the battery module, resulting in a 74% enhancement in thermal uniformity. Nevertheless, the integration of PCM inside the battery effectively prevents individual batteries from surpassing specified temperature limits. It yields a remarkable 36.64% enhancement in thermal uniformity compared to situations in which PCM is not present, albeit with a 3.75% capacity loss. Furthermore, the study investigates the effects of coolant flow rates and performs an extensive analysis of temperature variation and melting fraction.