Scaling approach of the convective drying of a porous medium
LMSGC, 2 allée Kepler, 77420 Champs-sur-Marne, France
Revised: 25 October 1999
Published online: 15 June 2000
We propose a simplified, theoretical approach of the evolution of liquid distribution during the convective drying of a granular packing. In the absence of gravity effects three regimes are distinguished according to the relative importance of surface evaporation, capillarity or evaporation from the interior of the sample. The evolution of the drying rate as a function of the saturation can be inferred from the characteristic velocities associated to each of these effects. We also carried out drying experiments of bead packings saturated with ethanol, at four different velocities of the boundary convection current, and with bead size ranging from 4.5 to 100 μm. The drying curves exhibit different regimes with a scaling as a function of particle radius and current velocity as predicted by the theory.
PACS: 68.10.-m – Fluid surfaces and fluid fluid interfaces / 81.05.Rm – Porous materials; granular materials / 92.40.Je – Evaporation
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2000