Mass transfer resistance of silica-gel micro particles adsorbing/desorbing water vapor in a flowing moist air.

In this study, we measured the adsorption and desorption rates of water vapor on the silica-gel particle layer with a step change of the surrounding relative humidity in a flowing moist air. As the results, time constants of a primary delay system for amount of adsorbed and desorbed water vapor were obtained in some air flow velocity on the layer. In addition, we obtained overall mass transfer resistance related to both the mass diffusion in the film and the mass transfer in the boundary layer on the layer. It was clarified that the resistance decreased with the increase of the velocity. Consequently, the resistance in the boundary layer was a negligible quantity when the flow rate was above 0.1 m/s. Finally, correlations were proposed to predict these resistances.