Numerical study on charging process inside a grid-structure thermal storage

Abstract

Heat transfer enhancement in different engineering systems is a major challenge nowadays. Phase change materials can be used for this purpose due to moderate phase change temperature, great thermal capacity, and great latent melting energy. The melting process of phase change materials that can be used in the management and reserving solar energy has been studied numerically in various grided solar storages. The novelty of this research is a numerical analysis of the phase change process in a grid structure with different small cells having impermeable heat-conducting walls. The characteristic equations including continuity equation, motion, and energy equations were solved by the finite element method as the melting process was developing. The influence of grid sizes and thermal conductivity of the solid material of thermal storage partitions on the fluid flow and heat transfer performance was studied. The heat transfer rate in a thermal storage system filled with the phase change material depends on the grid sizes. Moreover, a growth of the abovementioned small cells filled with phase change material reflects a diminution of the convective flow rate and as a result, the charging time increases. At the same time, a reduction of the inner solid walls heat conductivity characterizes a significant raise of the system charging time. As a result, it is possible to find optimal structure of such a storage system with effective energy transport parameters.