Regarding pressure in the adsorber of an adsorption heat pump with thin synthesized zeolite layers on heat exchangers

During the heating period of the adsorber in a water-zeolite adsorption heat pump. water desorbs from the zeolite. As a result, the adsorber pressure mainly increases because of the rise in vapor mass. Zeolite layers synthesized on metal supports in an adsorber have a low amount of zeolite with respect to the void volume, because they are thin. A small amount of zeolite has only a low adsorption capacity for the necessary pressure change. This communication demonstrates that, for thin zeolite layers with respect to the void volume of the adsorber, the pressure does not rise by following the isosteric line, but rises with a much smaller slope. Previously calculated heat pump performances with thin zeolite layers did not take into account this pressure effect which has a substantial and negative influence on the performance. (C) 2001 Elsevier Science B.V. All rights reserved.