MODELING CEREAL GRAIN DRYING WITH VARIABLE DIFFUSIVITY

The thin-layer drying or rough rice, maize and sorghum at several temp eratures was investigated. Stimulation of the experimental data was pe rformed by solving numerically the diffusion equation with variable di ffusion coefficient for spherical-shaped grain. To account for this va riation, an analytical expression for the dependence of the diffusion coefficient with moisture content was obtained based on considerations of the energy needed to dissociate water molecules form their sites a nd of resistance to diffusion. When the expression for diffusivity was used for predicting drying behavior of the grains, a good agreement w as obtained between experimental data and the theoretical prediction.