Heat transfer in phase change materials for integrated batteries and power electronics systems

An integrated batteries and power electronics system has great potential in improving the compactness, flexibility and multifunctionality in electrical vehicles. However, it needs to overcome thermal management challenges due to different operation temperatures of batteries and power electronics. To tackle this issue, this paper presents the first systematic study on the heat transfer characteristics in phase change materials (PCMs) based thermal management system sandwiched between two significantly different constant heat sources, through an experimentally validated transient three-dimensional heat transfer model. All key parameters of PCMs affecting the system are identified through a new dimensionless formulation, including the ratio of horizontal and vertical thermal conductivity kxy and kz, the aspect ratio (ratio of thickness and length), and Jakob number Ja (ratio of sensible heat and latent heat). Modelling results show that the system operation duration & tau;d increases monotonically with the increase of kxy. However, increasing kz is not always benificial for & tau;d and there is an optimal value for kz when keeping kxy unchanged. In addition, the increase of PCMs thickness can prolong & tau;d monotonically. The reduction of Ja, e.g. increasing latent heat, is always beneficial for & tau;d.