ISSN Online: 2377-424X
ISBN Print: 978-1-56700-474-8
ISBN Online: 978-1-56700-473-1
International Heat Transfer Conference 16
EFFECTS OF SUCTION AND SPILLAGE ON SUPERCRITICAL CARBON DIOXIDE-BASED DRYING OF AEROGELS
Sinopsis
When solvent, typically ethanol or methanol, is extracted from a silica aerogel during supercritical carbon dioxide-based drying of it, the effects of "suction" and "spillage" arise due to the density of the fluid in the aerogel non-monotonically changing as the solvent mass fraction is reduced. Hence, the drying process is not purely diffusive, but has an advective component. We capture the effects of this on the kinetics of drying. The geometry considered is an inner annulus of silica aerogel, concentric with an outer annulus through which
supercritical carbon dioxide is pumped. The aerogel is modeled as a porous medium using Darcy's Law and the outer annulus as an open region. Compressibility effects are captured in the coupled regions as is a mass fraction-dependent molecular diffusivity in the species equations.