Adsorption Equilibrium and Desorption Rate of Adsorbent Coated on Heat Transfer Plate

Abstract

Enhancement of adsorption/desorption rate in an adsorption heat exchanger is effective to downsize adsorption chillers and desiccant systems. Exothermic/endothermic phenomena during adsorption/desorption decrease with the adsorption/desorption reaction rate, so that it is necessary to improve the heat transfer performance of adsorption heat exchanger. Thin film adsorbent coated on the plate is promising to enhance the heat transfer, because it has large contact area on the plate. In the previous study, it was clarified that the heat transfer performance of a porous alumina thin film as an adsorbent coated on an aluminum plate was greater than that of conventional particle packed bed of activated alumina. In this study, the adsorption equilibrium and the desorption rate of porous alumina thin film were measured. The parameters in BET equation were determined and Polanyi's potential theory was examined. In addition, effective diffusivity of water vapor in desorption process was formulated.