Intermittent Drying of Rice Grains with Husk: Modelling and Experimentation

This chapter presents an analytical modeling of mass transfer in wet porous bodies during the continuous and intermittent drying process in fixed bed. The drying process was simulated assuming the liquid diffusion as the only mass transport mechanism and constant mass diffusion coefficient. The presented models involve spherical, cylindrical and prolatespheroidalgeometries. Simulation tests of intermittent drying of ellipsoidal solids were performed and the results were compared with the continuous drying curve in order to evaluate the tempering effect in the drying process optimization. It was possible to simulate the moisture distribution during the tempering period. As an application, the methodology is used to describe intermittent drying of rough rice (BRSMG Conai variety) at temperature of 40°C and tempering periods from 0 to 1 hour. Experimental data were used to estimate the diffusion coefficient. Under the considered operating conditions, it was verified that intermittent drying provides reduction in effective operating time when compared to continuous drying.