Experimental and numerical study on drying behavior of CORN grain

Abstract

Tower type grain dryers are widely used in corn drying process and are manufactured as cylindrical structures with a height of about 30 m. Grain is filled into the annular section between the perforated walls and dried with exhaust gas from the combustion chamber. In terms of drying quality and energy efficiency, high capacity drying systems need a reliable control system. In the current study, a laboratory scale test prototype of this type of industrial grain dryer is installed to determine the most suitable model to be used in the control system. A fixed bed design has been made that allows hot exhaust gases to enter the drying chamber horizontally, as in industrial tower dryers. Corn drying experiments were carried out experimentally to reveal and model the drying behavior of corn, to examine the effect of air velocity on pressure drop and drying, to show the usability of equations commonly used in the literature. Drying gas temperature is kept constant at 103 °C and inlet gas velocity values are changed to find out velocity effects on pressure drop and drying behavior. Experimental data are modeled with a curve fitting method using MATLAB software. Lewis, Page, Henderson and Pabis, Logarithmic, Midilli and Wang and Singh models, which are known as thin-layer models in the literature are used. The effect of drying air velocity on the coefficients of the best thin layer drying model was determined. Results show the most suitable model is the Midilli model. The obtained results are given in comparison with the results in the literature and a model is proposed for use in control of industrial dryers.