A novel desiccant compound for air humidification and dehumidification

Abstract

• A novel silica gel-based desiccant material for open air systems is proposed. • Silica gel is mixed with sodium polyacrylate, vinyl glue and polypropylene fibers. • The maximum water uptake on dry silica gel mass basis is equal to 0.32 kg kg −1 . • Thermal and sorption stability of new and on-purpose aged samples are observed. • Dehumidification capacity is around 3.5 g kg −1 when the regeneration occurs at 52 °C. Currently, there is an increasing interest in the development of HVAC systems based on solid desiccant materials to achieve efficient and affordable air dehumidification and humidification processes. Many research efforts deal with the development of novel composite materials suitable to manufacture such devices. In this work we present a novel silica gel-based desiccant compound, which can be used to prepare different products, such as sheets, monolithic components, and coatings. The proposed formulation is based on a combination of silica gel, sodium polyacrylate, vinyl glue and polypropylene fibers. The preparation procedure of the sorbent material and its characterization (adsorption capacity, morphology and surface analysis, mechanical properties by pull-off test, structural and thermal stabilities of new and aged samples and volatile compounds emissions) are described in detail. A small-scale prototype has been also manufactured and experimentally tested under typical operating conditions of air dehumidification processes. Results show that the proposed material has a suitable sorption capacity (maximum water uptake equal to 0.32 kg kg −1 ), good mechanical properties (pull adhesion strength around 2.74 MPa) and stability (decomposition threshold of 400 °C). The performances achieved by the prototype are comparable with those of a reference silica gel packed bed system, highlighting that the desiccant material performs adequately also at system scale.