Continuous and Intermittent Drying (Tempering) of Oblate Spheroidal Bodies: Modeling and Simulation

Abstract In this work, modeling of continuous and intermittent drying of oblate spheroidal bodies is presented. The model considers the liquid diffusion as the only process of mass transfer inside the body, constant diffusion coefficient and equilibrium conditions at the surface of the solid. The diffusion equation is described in the oblate spheroidal coordinates system and it was discretized using the finite-volume method. Formulation was applied to predict drying of lentil grains. Several cases of intermittent drying for lentils were simulated: using a same time of tempering (time of rest), beginning in different drying time and for two or more drying passes (time steps) along the process. For a same useful time of the dryer, it was observed that the intermittent drying always increases the efficiency of the process. Another outstanding result is the improvement of the final quality of the product due to the absence of large moisture content gradients inside of the product during the drying process after tempering.