Analysis of a Fabric/Desiccant Window Cavity Dehumidifier

Abstract

This paper presents the results of an exploratory study of a fabric/desiccant window cavity dehumidifier system for possible use in commercial buildings. The objective was to evaluate fabrics commonly used in buildings, and system concepts that employ these fabrics, which can be used to dehumidify room air. We developed a first-order energy/mass balance model to determine the performance of a window cavity dehumidifier that uses silica gel encapsulated in a fabric matrix rotating on a belt alternately through dehumidification and regeneration chambers; the modeling effort was supplemented by environmental chamber measurements of the moisture absorption characteristics of 16 fabric/desiccant combinations. We ran the model for a typical office building module, for outside air design conditions characteristic of the most difficult humidity regime in Texas. Two flow configurations, outside air and return air, were evaluated to determine the capability of such a system to dehumidify the air streams under consideration. Issues addressed included the physical limitations on the amount of desiccant that can be included in this configuration and the degree of dehumidification achievable.