Thermal conductivity, pore structure and adsorption performance of compact composite silica gel

A novel composite solid desiccant material is proposed in this study to enhance thermal conductivity and adsorption performance of silica gel. This desiccant material is fabricated by combining silica gel with expanded natural graphite treated with sulfuric acid (ENG-TSA) as a host matrix. The performance of this composite material with respect to different densities and different silica gel ratios was investigated. Experimental results showed that the highest thermal conductivity of consolidated composite adsorbents is 19.1 W m−1 K−1. This is an increase of more than 270 times as compared to that of pure silica gel. Analysis on pore parameters demonstrated that the compression of simple mixture of ENG-TSA with silica gel does not destroy the morphology of silica gel. In addition, both non-equilibrium and equilibrium adsorption performance of composite silica gel and pure silica gel were evaluated. Non-equilibrium adsorption performance indicated prominent enhancement of heat transfer, whilst equilibrium adsorption performance indicated a reasonable mass transfer.