Three-Dimensional Transient Heat, Mass, Momentum, and Species Transfer in the Stored Grain Ecosystem: Part II. Model Validation
The 3D heat, mass, momentum, and species transfer model for the stored grain ecosystem was validated using data collected from bins filled with corn at West Lafayette, Indiana, and wheat at Stillwater, Oklahoma. Linear and quadratic elements were used in the validation of the finite element model. Input to the model was hourly weather data such as total solar radiation, wind speed, ambient temperature, and relative humidity. The predicted grain temperatures were in accordance with the observed data. The conduction plus natural convection model predictions had a lower standard error than the conduction model. For the two locations, the standard error of prediction of grain temperatures for the conduction plus convection model was in the range of 0.9°C to 3.6°C for wheat and 1.0°C to 3.1°C for corn. The linear heat transfer model predicted reasonably well compared to the quadratic model for wheat, whereas the quadratic model was more accurate for corn. The predicted moisture content followed the trends of observed data with a standard error in the range of 0.1 to 1.28 percentage points. The absolute difference between the predicted and observed species concentrations was in the range of 0 to 0.3 mg L-1. The 3D stored grain ecosystem model validated in this study can therefore be used to predict with confidence grain temperature, moisture content, natural convection, and species concentration changes in a stored mass of any type of grain in a cylindrical corrugated steel structure of any size at any geographical location.