DEVELOPMENT OF A FINITE–ELEMENT STORED GRAIN ECOSYSTEM MODEL

Abstract

An axisymmetric finite–element model was developed that predicts the heat, mass, and momentum transfer that occurred in upright corrugated steel storage structures due to conduction, diffusion, and natural convection using realistic boundary conditions. Weather data that included hourly total solar radiation, wind speed, ambient temperature, and relative humidity were used to model the temperature, moisture content, dry matter loss, and maize weevil development 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. Heat and mass balances were used to calculate the temperature and absolute humidity in the headspace and plenum based on solar radiation, wind speed, ambient conditions, air infiltration, convective heat and mass transfer from the grain surface, and permeable boundaries that allowed natural convection currents to cross grain surfaces. A heat balance was used to estimate the wall temperature. The type of weather data in terms of solar radiation and frequency of data appear to be important when predicting the grain temperature, moisture content, dry matter loss, and maize weevil development.