Experimental investigation on the adsorption kinetics of silica-gel layer enhanced thermal conductivity

Highlight• The adsorbent rate is improved after doping with high-conductivity carbon fiber. • Layer diffusion resistance is not the limiting step in these conditions. • Heat transfer is more strongly affected than layer diffusion in these conditions. Desiccant air conditioning by heat exchange with an adsorbent driven by waste heat has the potential to become a highly efficient process because latent and sensible heat can be controlled independently. However, the mass and heat transfer phenomena that occur in the heat exchanger with the adsorbent are too complex to be expressed. Therefore, we attempted to elucidate the effect of thermal conductivity on adsorption kinetics by a volumetric method. In addition, we experimentally investigated the adsorption kinetics of a silica gel layer. The thermal conductivity of the silica gel layer increased in the range of 0.2–2.0 W/(m·K) at 303 K, which drastically increased adsorption kinetics. Moreover, there is an optimal point in water adsorption power per volume because of the relationship between packing density and content ratio of carbon-doped silica gel.