Design of a mobile thermal battery and analysis of thermal characteristics

Thermal characteristics of a mobile thermal battery, consisting of a steel tube, metallic meshes, and the phase change material, are investigated. Concentrated solar heating of the steel tube is considered and the governing equations of heat transfer and the flow field, due to the natural convection, are solved numerically. Lithium nitrate is used as a phase change material due to its high latent heat of melting and aluminum is used as the metallic mesh material. The maximum and minimum temperature difference in the tube is predicted and the temperature parameter is introduced to assess the thermal storage performance of the mobile thermal battery. The numerical code is validated with the data reported in the early study and findings revealed that both results are in good agreement. It is found that temperature predictions agree well with the previous data. The use of metallic meshes inside the steel tube significantly improves the heat conduction in the phase change material. In this case, almost uniform temperature distribution is achieved inside the tube during the cycle of thermal energy storage. Sensible heating in the liquid phase of the phase change material results in the increase in the localized excessive temperature, which has an adverse effect on achieving a uniform temperature distribution inside the thermal battery.