Squaring the circle in drying high-humidity air by a novel composite sorbent with high uptake and low pressure-drop

Abstract

A novel sponge-structured composite sorbent was prepared for drying of air with relative hu-midity higher than 60% RH. The composite consisted of CaCl2 in a mesoporous silicagel host matrix consolidated with poly(vinyl alcohol) binder. The uptake capacity was determined by thermogravimetric vapor sorption analysis. Air drying performance was tested in an open sorption bed that also allowed pressure drop measurements. The bulk density of the composite sorbentis about 3 times lower than a benchmark microporous silicagel. Thus, the water removal for fixed volumes of the composite sorbentis lower than the water removal for fixed volumes of silicagel. However, the composite sorbent increased mass-specific uptake by a factor of 2.6 and reduced pressure drop by a factor of 8 to 10 compared to silicagel. The higher mass-specific uptake and the lower pressure drop enable the proposed novel composite sorbent to reduce adsorber weight and fan power in adsorption drying.