Storage of thermal energy for effective use of waste heat from industries

Abstract

Energy saving is one of the most effective strategies to protect the global environmental conditions. At present, considerable amount of waste heat is emitted from metallurgical and chemical industries, which can be used not only for municipal purposes but also for industries if recovered.In this paper, fundamental studies on heat transfer was conducted for developing a heat storage process by latent heat for recovering the high temperature waste heat over 500 K. Heat transfer experiments were attempted for a single encapsulated phase change materials and for a packed bed. Six different materials were tested as PCM from the points of view of high energy density storage, chemical stability, non-toxicity and cost performance. Those were two inorganic and four metallic materials. A single capsule containing PCM was heated for heat storage and then cooled for heat release in nitrogen gas stream where convective heat transfer was predominant.The metal PCMs were found to be excellent for heat storage because of uniform temperature in the capsule. Heat transfer simulation was also conducted for a packed bed process of spherical capsules providing the fundamental informations on the optimal design. As a result, concurrent flow for heat storage and release showed better result for effective use of storaged heat than counter-current flow. Exergy efficiency was also evaluated.