VALIDATION OF A FINITE–ELEMENT STORED GRAIN ECOSYSTEM MODEL

Abstract

An axisymmetric finiteelement model was validated with respect to predicting the heat, mass, and momentumtransfer that occurred in upright corrugatedsteel storage bins due to conduction, diffusion, and natural convection usingrealistic boundary conditions. Hourly weather data that included hourly total solar radiation, wind speed, ambienttemperature, and relative humidity were used to model the corn temperature and moisture content during storage with noaeration, and with ambient and chilled aeration. Periods of aeration were simulated assuming a uniform airflow rate throughthe grain mass. Sixteen bins with a capacity of 11.7 t each and instrumented with temperature cables were available to validatethe model using two years of measured corn temperatures and moisture contents during summer storage. The averagestandard error between the experimental and predicted temperatures was 2.4C (1.1C to 5.7C range), and the standarderror between experimental and predicted moisture contents was 0.7 percentage points. The average standard error was 1.5Cin three nonaerated bins with sealed plenums when corn temperature was predicted as a function of the natural convectionequation. The predicted natural convection effect was not applicable unless the plenum was assumed sealed.