Abstract
When a hydration reaction can be operated reversibly by alternate removal and addition of the reaction heat, it is utilized for operating a multipurpose process with various capabilities of heat pumping, recovery of pure water, low temperature concentration, freeze concentration and so on. This paper deals with a fundamental study to develop multipurpose chemical heat pumps driven by the hydration reaction of calcium chloride, whose principle and potentialities are described in the first part. To elucidate the mechanism that the hydration reaction stopped at a low yield, the reaction rates were measured after performing short-period vacuum desorption of the surface water and the surface structure of the reacted particles was observed by SEM. Based on these investigations a reaction model has been proposed, which can simulate the reaction progress by taking account of the condensation of water molecules absorbed on the particle surface.
