Renewable Energy, Vol.86, 785-795, 2016
Steady-state investigation of water vapor adsorption for thermally driven adsorption based greenhouse air-conditioning system
In the present study, water vapor adsorption onto silica-gel, activated carbon powder (ACP) and activated carbon fiber (ACF) has been experimentally measured at 20, 30 and 50 degrees C using a volumetric method based adsorption measurement apparatus for greenhouse air-conditioning (AC). The Guggenheim-Anderson-De Boer and Dubinin-Astakhov adsorption models are used to fit the adsorption data of silica-gel and ACP/ACF, respectively. The isosteric heat of adsorption is determined by Clausius-Clapeyron relationship. The adsorbents are evaluated for low-temperature regeneration with aim to develop solar operated AC system for greenhouses. Ideal growth zone for agricultural products is determined by which the steady-state desiccant AC cycle is evaluated on the psychometric chart and adsorption isobars. Steady-state moisture cycled (MCSS) by each adsorbent is determined for demand category-I, II and III which are based on 60%, 40% and 20% relative humidity of dehumidified air, respectively. In case of demand category-I, the ACP enables maximum MCSS at all regeneration temperatures (T-reg), ideally sitting at 47 degrees C. The ACF enables double MCSS as compared to silica-gel during demand category-II at T-reg >= 59 degrees C. However, the silica-gel is found the only applicable adsorbent for the demand category-III. (C) 2015 Elsevier Ltd. All rights reserved.