Storage and release of heat in a single spherical capsule containing phase change material of high melting point.

A latent heat thermal storage system using a packed bed is one of the most attractive recovery methods of periodically generated waste heat in industrial processes. The thermal performance of the system depends largely on that of a single spherical capsule containing phase change material (PCM). In this study, PCMs were investigated as materials to recover and store heat for the temperature range between 500 and 1100K. Some inorganic salts and metals were selected from the point of view of higher latent heat, chemical stability, nontoxicity, inexpensiveness. Heat storage and release experiments of single capsules under the condition of predominant convective heat transfer were carried out. The results were favorably simulated by a mathematical model derived from enthalpy balance. For obtaining constant-temperature gas, metallic PCMs were more advantageous than inorganic salts because of higher thermal conductivity.