Numerical investigation of form-stable composite phase change material for battery passive cooling

Phase change material (PCM) has gathered much attention in battery thermal management for electric vehicles, in which form-stable PCM is a promising method to reduce the leakage of energy storage material. In this paper, a composite PCM that has form-stable property is used for passive cooling of electric car battery. Three cooling configurations are set up in the gap between two batteries, and their performance is analysed by a numerical model. The results show that integrating composite PCM with forced air convection can maximally prevent battery from heat accumulation at 5C and reduce the core temperature by 15.9 K, while filling the gap with composite PCM can reduce the temperature by 15.7 K. With the discharge rate decreased, forced air convection plays more significant role than PCM in slowing down the rise in battery temperature. The maximum battery temperature reduces when the ratio of PCM thickness to battery width increases from 0 to 0.1, but the maximum temperature is limited to a certain level with thicker PCM. The addition of 4.6 wt% graphite to the composite PCM greatly improved the heat absorption capacity of PCM, and the forced air with 20 m & BULL;s-1 velocity has better cooling behaviour than PCM.