COMPARISON OF MATHEMATICAL-MODELS TO SIMULATE AERATION OF WHEAT STORED IN BRAZIL

Equilibrium and non-equilibrium heat and mass balance models are compa red to simulate aeration of stored wheat under tropical and subtropica l climates using both linear and non-linear airflow distributions. The approach used was to compare deviations in predicted grain deteriorat ion instead of deviations in grain moisture content and temperature. T he results produced by the equilibrium and non-equilibrium models were significantly different (P=0.05) when simulating aeration of wheat st ored for 1 yr in Curitiba, Brazil because the deviations in grain dete rioration were equal to or greater than the uncertainty in predicting deterioration (+/-30%) for most test conditions. The non-equilibrium m odel appears more appropriate than the equilibrium model for simulatin g aeration of stored wheat because it is based on experimental thin-la yer drying and wetting equations and equilibrium moisture content equa tions for desorption and adsorption. In addition, the equilibrium mode l over-predicts wheat moisture content and temperature, causing an ove r-prediction of grain deterioration. It is concluded that a more accur ate deterioration model is needed to increase the uncertainty in predi cting wheat deterioration for simulated aeration of stored wheat. (C) 1996 Silsoe Research Institute