Numerical investigation on integrated thermal management for a lithium-ion battery module with a composite phase change material and liquid cooling

A novel thermal management system was proposed based on paraffin (RT44HC)/expanded graphite (EG) composite phase change material (CPCM) coupled with liquid cooling to maintain the temperature rise and difference within a desirable range of lithium-ion batteries at a discharge rate of 3C. A numerical research was conducted by computational fluid dynamics (CFD) to investigate the effects of the battery's thermal characteristics at an ambient temperature of 40 degrees C at various flow velocities, channel arrangement and CPCM with different mass fraction of EG. Furthermore, the thermal behavior of the integrated thermal management system (ITMS) in a charge-discharge cycles was analyzed. The results indicate that the heat dissipation of the battery pack is enhanced with an increase of the flow velocity, but when the flow velocity is greater than 0.08 m/s, the increase of the flow velocity imposes little effect on further improving heat dissipation performance of the ITMS. The channel layout of Type I indicates the optimal cooling performance at various flow velocities. Compared with the pure paraffin phase change material (PCM), the maximum temperature is reduced by 2.1 degrees C, and the temperature difference is only 2 degrees C in the ITMS, with an EG of 6 wt%. On charge-discharge duties, the maximum temperature and the initial temperature are constant at the lower liquid flow velocity of 0.04 m/s, and the ITMS with an EG of 6 wt% meets the requirements for heat dissipation.