MODELING AND SIMULATION OF CROSSFLOW MOVING BED GRAIN DRYERS

ABSTRACT

The drying of grain in dryers of a crossflow moving bed type was theoretically and experimentally studied. Two different dryer configurations were analyzed, a dryer with central air distribution and another with multiple air duels. Experimental information was obtained in pilot-size dryers. A mathematical model to simulate the process was developed. Hindered drying was accounted for by using the concept of relative drying rate. An adjustable factor, specific to the dryers, was used to account for the uncertainties of the contact area and the transfer coefficients encountered in the literature. Agreement between experimental results and simulations was fairly good. Simulations showed that distance between inlet air and outlet devices, air to solid flow ratio and dryer height to cross section ratio have great influence on the process. The mathematical model may be a useful tool for process exploration and optimization of this type of dryers.