SENSITIVITY ANALYSIS OF A MATHEMATICAL-MODEL TO SIMULATE AERATION OF WHEAT STORED IN BRAZIL

The research objective was to determine the relative importance of sev eral variables in a non-equilibrium mathematical model for simulating aeration of stored wheat with uniform and non-uniform airflow distribu tions. The relative importance of each variable was determined by addi ng or subtracting fixed uncertainties from that variable and by calcul ating the effect of these changes on the predicted grain deterioration , after 1 year of storage. Results of simulations using weather data f rom Curitiba, Brazil, ventilation time of 06:00-12:00, fan temperature rises of 1 and 3 degrees C, and linear airflows of 0.0056 and 0.0278 m(3)/s per m(2) indicated that the most important variables, in decrea sing order, were the fan temperature rise, thin-layer wetting equation , and thin-layer drying equation. Wheat bulk density can be a constant and the net heat of sorption can be neglected. The ratio of bin diame ter to bin height and the accuracy of the equations to describe wheat specific heat, air resistance to airflow, and equilibrium moisture con tent for adsorption and desorption were not important in the mathemati cal model. The deterioration model must be improved because the uncert ainty in the calculation of wheat deterioration was much higher than t he uncertainty generated by many of the other variables for the Brazil ian climate. (C) 1997 Elsevier Science B.V.