Water vapor adsorption kinetics on small and full scale zeolite coated adsorbers; A comparison

A possibility to enhance both heat and mass transfer characteristics of an adsorber heat exchanger is to apply the adsorbent directly to its surface in form of a consolidated layer. As the majority of the available publications on the effect of both coating technology and adsorbent layer thickness on the adsorption kinetics deals with small scale adsorbent samples, the results obtained can only represent the best case design of an adsorber heat exchanger. This article presents, therefore, a comparison between the adsorption kinetics of water vapour on small as well as two different full scale coated adsorber heat exchanger types with AQSOA-202 layers of Mitsubishi Plastics Incorporation under quasi isobaric conditions of adsorption heat pumps. The small scale coated samples have a zeolite dry mass of 200 mg and layer thicknesses of 200, 300 and 500 gm while the full scale adsorbers have a coated zeolite mass between 1.5 and 2.5 kg and layer thicknesses of 150, 200, 300, 400 and 500 gm. In the investigated adsorption heat pump module, up to 52.7 and 573% of the equilibrium differential water loading measured with the small scale coated substrates have been obtained after an adsorption-evaporation times of 300 and 600 s, respectively. (C) 2011 Elsevier Ltd. All rights reserved.