Investigation on regeneration of zeolite 13X-water adsorbent bed under vacuum condition: A computational approach

Abstract

The present work investigates the adsorbent regeneration numerically in a vacuum to enhance adsorption-cooling systems' performance. A two-dimensional study on the desorption of water vapor from a zeolite 13X bed in a vacuum is studied using COMSOL Multiphysics. Coupled mass, heat, and momentum equations are solved for the adsorbent bed with different particle sizes to estimate temperature and moisture variation. The simulation is validated with experimental results from the literature. The study shows that the particle diameter significantly affects the mass transfer coefficient related to the desorption process. An increase in particle diameter from 3 to 4 mm decreased the mass transfer coefficient by 43.8 %, and 3 to 5 mm was reduced by 64.0 %. Similarly, in the case of desorption, particles with size 3 mm had the maximum desorption rate (0.27–0.14 kgw/kgadsorbent). An increase in particle diameter from 3 to 4 mm and 3 to 5 mm reduced the desorption process by 8.4 % and 13.8 %, respectively. The temperature change in a straight line along the radial direction of the adsorbent bed is computed, and the result showed that heat input affects the heat transfer rate but not its direction. As the desorption of an adsorbent bed depends on various parameters, an optimization study should be carried out to optimize particle size, height and width of the bed, thermal conductivity, working pressure, moisture content, and regeneration temperature.