MASS-TRANSFER LIMITED DRYING OF POROUS-MEDIA CONTAINING AN IMMOBILE BINARY-LIQUID MIXTURE

A theory was developed to predict transient effluent concentrations, liquid concentrations, and the position of the evaporation front during external (mass transfer limited) drying of a porous material containing an immobile binary liquid mixture. One-dimensional drying experiments were performed with different binary mixtures to assess the validity of the model. Theoretical and experimental findings showed that the evaporation during mass transfer limited drying was non-selective in terms of component volatility; the mass fractions of the compounds in the effluent gas remained near the mass ratio of the emplaced liquid mixture. The effluent concentrations and the velocity of the evaporation front were shown to be proportional to t(-1/2). A growing zone of variable liquid concentrations was shown to exist near the penetrating evaporation front.