Journal of Materials Science, Vol.29, No.4, 943-948, 1994
Drying of Silica-Gels with Supercritical Carbon-Dioxide
Results of drying experiments of aerogels with supercritical carbon dioxide are reported. In addition to the results of experiments with a pilot extracting apparatus, a preliminary design is also given of a large-scale supercritical carbon dioxide extraction plant to be used for drying of aerogels. From the experiments it was found that crack-free aerogels could be obtained when drying with carbon dioxide under supercritical conditions. The lowest temperature and pressure at which crack-free aerogel samples were obtained was at 35-degrees-C and 85 bar, respectively. The temperature had a minor influence dn the drying time. It was also found that the diffusion of ethanol into the aerogel pores limits the drying time. This limitation implies that the thickness of the aerogel tiles will have a large influence on the cost of drying of an aerogel.
Keywords:MOISTURE TRANSPORT;PACKED-BEDS