Experimental investigation of a solid desiccant system with the staged adsorption/desorption process

Abstract

The staged solid-desiccant dehumidification system (SSDD), recently proposed to approach the thermodynamic efficiency limits of cyclic adsorption and desorption, has received little experimental scrutiny. We built and tested a pilot-scale SSDD comprising two fixed beds arranged in series (coated with SAPO-34 and EMM-8) and benchmarked it against a conventional silica gel system over various conditions. The dehumidification and regeneration processes were investigated separately. The SSDD delivered markedly superior dehumidification performance and exploited regenerative heat in a cascade fashion. Over the dehumidification runs, the SSDD achieved a maximum cumulative moisture removal advantage of 18.5 g. By contrast, silica gel displayed only a short-lived edge — confined to the first minute of every test, and its cumulative moisture removal never exceeded the SSDD by more than 2.04 g before being steadily overtaken. A distinctive ”M-shaped” instantaneous moisture removal profile in the SAPO-34 bed verified the predicted rapid adsorption phase driven by cooperative uptake. Regeneration tests confirmed a critical regeneration temperature of 90 $\sim$ 110 °C, above which cascade utilization of regeneration heat enabled rapid desorption in both beds. These findings validated the two key advantage mechanisms of staged adsorption/desorption – (i) a sustained mass-transfer driving force and (ii) cascade energy utilization – and highlighted the SSDD’s potential as a high-efficiency solution for solid-desiccant dehumidification.