Heat storage materials, geometry and applications: A review

This paper reviews various kinds of heat storage materials, their composites and applications investigated over the last two decades. It was found that sensible heat storage systems are bulkier in size as compared to the latent heat storage systems. Latent heat storage system using phase change materials (PCMs) stores energy at high density in isothermal way. Various geometries of PCM containers used for enhancement of heat transfer area, materials used for the construction of PCM containers and their interaction with heat storage materials are studied. The choice of storage material depends on the desired temperature range, application of thermal storage unit and size of thermal storage system. Low temperature heat storage system uses organic phase change materials while inorganic phase change materials are best suited for high temperature heat storage. Heat transfer within the PCM can be enhanced by preparing composite of high thermal conductivity as well as by altering the geometrical design like addition of fins, use of straight and helical tubes etc. Shell and tube configurations were mostly used for thermal storage systems. Heat transfer enhancement using PCM composite is a promising approach as it reduces cost and bulkiness to the system.