Abstract
Enhancement of adsorption/desorption rate in adsorption heat exchanger is effective to downsize adsorption chillers and desiccant systems. Exothermic/endothermic phenomena during adsorption/desorption decrease adsorption/desorption reaction rate, so it is necessary to improve the heat transfer performance in the heat exchanger. Heat transfer of particle adsorbent packed bed in the conventional heat exchanger is relatively not good, because the contact area between the adsorbent particles or between the particle and the heat transfer plate are very small. In contrast, a thin film adsorbent coated on the plate which we propose here is promising to enhance the heat transfer performance, because contact is between the film adsorbent and the heat transfer plate only and the contact area is large. This study focused on a porous alumina thin film on an aluminum plate as a coated adsorbent. The thermal resistance of the film was measured and found to be smaller than that of a packed bed of activated alumina particle. It was clarified that the difference in the resistance between them became larger with an increase of the thickness, that is an advantage of coated type.
