Diffusion and adsorption of moisture in desiccant sheets



The simultaneous diffusion and adsorption of water vapor into specially prepared silica gel and activated carbon desiccants was experimentally studied for laminar flow through an isothermally maintained parallel-plate channel. The equilibrium characteristics and tortuosities of the various desiccant sheets used were experimentally determined.

The data were compared with a modified Rosen model. The Rosen model predicts outlet concentrations from the knowledge of adsorption equilibrium constants, diffusion, and mass transfer coefficients. A comparison of computed and measured concentrations as a function of sorption time shows that with independently measured equilibrium and effective diffusion coefficients, the modified Rosen model became completely predictive.