Journal of Supercritical Fluids, Vol.140, 394-405, 2018
Aerogel production by supercritical drying of organogels: Experimental study and modelling investigation of drying kinetics
A supercritical process to dry organogels, in order to produce aerogels is studied. The organogel is firstly produced by synthesizing an amino-acid-type organogelator of fibrillary structure, which is able to trap a solvent, here tetralin. The extraction of tetralin from the organogel using supercritical CO2 is then investigated both through experiments and simulations. Two approaches are developed in order to understand the tetralin mass transfer mechanisms. In the first approach, the organogel is regarded as an impenetrable material and the mass transfer within it is assumed to be only diffusive. In the second approach, the organogel is considered as a penetrable porous material so that CO2 can flow across it. The tetralin transfer is thus governed both by diffusion and convection. Both approaches are implemented in Computational fluid dynamics (CFD) software ANSYS Fluent. The drying kinetics obtained by the second approach is found to agree better with the experimental results.