Experimental studies on a novel chemical heat pump dryer using a gas-solidreaction

The authors have been studying Chemical Heat Pumps (CHP) from the viewpoint s of energy saving and environmental impact. The CHP can store thermal ener gy in the form of chemical energy by an endothermic reaction, and release i t at various temperature levels during heat demand periods by exo/endotherm ic reactions. The authors have proposed in an earlier study a novel chemica l heat pump (CHP) system for environmentally-friendly effective utilization of thermal energy in drying as a chemical heat pump dryer (CHPD). In this exploratory study, we test the effectiveness of operating the proposed CHPD s experimentally. Basic experiments on the CHPDs such as hot dry air produc tion for convective drying are performed on lab-scale CHPD apparatuses usin g gas-solid reactions in calcium oxide/calcium hydroxide reactant beds. The proposed CHPDs are found to produce hot air by CHP operation for drying. T he temperature levels of the produced hot air and the reaction rates/conver sions are as good as in the case of hot water supply system using basically same CHP operation. The cold heat for air dehumidification is also found t o be generated/recovered by the same CHPD system. The generated heat amount s can be increased by changing the operating conditions although the heat r ecovery must be enhanced for practical application of CHPDs.