Validation of a finite-element stored grain ecosystem model

An axisymmetric finite-element model was validated with respect to predicting the heat, mass, and momentum transfer that occurred in upright corrugated-steel storage bins due to conduction, diffusion, and natural convection using realistic boundary conditions. Hourly weather data that included hourly total solar radiation, wind speed, ambient temperature, and relative humidity were used to model the corn temperature and moisture content during storage with no aeration, and with ambient and chilled aeration. Periods of aeration were simulated assuming a uniform airflow rate through the grain mass. Sixteen bins with a capacity of 11.7 t each and instrumented with temperature cables were available to validate the model using two years of measured corn temperatures and moisture contents during summer storage. The average standard error between the experimental and predicted temperatures was 2.4° C (1.1° C to 5. 7° C range), and the standard error between experimental and predicted moisture contents was 0.7 percentage points. The average standard error was 1.5° C in three non-aerated bins with sealed plenums when corn temperature was predicted as a function of the natural convection equation. The predicted natural convection effect was not applicable unless the plenum was assumed sealed.