Energy upgrading by solid–gas reaction heat transformer: A critical review

The solid–gas reaction heat transformer, which can upgrade the temperature of middle-grade heat (such as industrial waste heat, solar energy, geothermal energy, etc.) is considered promising for energy-saving in the near future. It provides high storage capacity of heat, wide range of working temperatures as compared to other heat transformers. In addition, it uses all natural working pairs, which are friendly to the environment. For its complicated chemical kinetics, high requirement for safety, low system efficiency, large investment, etc., it has not been widely used yet. This paper gives a comprehensive review of the research done on solid–gas reaction heat transformers regarding the status of technology (such as thermodynamic cycles, working pairs, system performance, etc.) and current applications and future prospect, with special reference to effective utilization and storage of industrial waste heat and solar energy, long-distance heat transport and district heat supply, etc.