Modeling the Drying of Wheat Seeds in a Fluidized Bed Using a Spatially Resolved Model

Abstract

Abstract. A mathematical model for simulating heat and mass transfer during fluidized-bed drying of wheat grains has been developed, combining two transfer steps; a movement of moisture inside the grain and outside the grain. Empirical equations have been used for material properties as well as for transfer processes. The developed model is composed of two models coupled to each other; the distributed parameter model (DPM or Luikov model) and the convective model. The coupled mathematical model was solved numerically by a finite difference method after discretization of equilibrium equations distributed in space. The DPM model made it possible to predict the quantity of water extracted from the grain under the effect of known drying conditions. Results showed that the drying rate of wheat increased when air temperature was increased; and that the rates were higher in the first few minutes of drying, achieving 2.6 × 10-5and 1.7 × 10-5 kg water kg-1[d.b.]·s-1 for temperatures of 66.7°C and 58.6°C, respectively. A comparison of experimental and predicted results gave good agreement, and the use of the distributed model improved the predictive capabilities of wheat grain drying in fluidized beds. Keywords: Canada Western Red Spring, Distributed parameter model, Fluidized-bed dryer, Mathematical modeling, Wheat seeds.