A model of grain aeration in a grain silo

When grain is stored in a silo, a stream of air should be forced through the grain bed to improve its storability. The purpose of forced ventilation is to air, cool, or dry stored grain. The intensity of these processes is determined by various factors, including airflow velocity distribution inside the silo. In turn, airflow velocity distribution is influenced by the parameters of the supplied air, the parameters of the stored plant material, as well as by the silo’s structural characteristics. The aim of this study was to propose a model of airflow velocity distribution in a grain bed depending on the values of the above parameters. A mathematical model was developed, formalized, and implemented in a selected programming environment. For the needs of the model, the volume of a silo filled with grain was divided into a finite number of elements with the use of discretization principles that were strictly formalized by the authors. It was assumed that air would flow away from or towards all neighboring elements, as well as across the walls in perforated silos, unless constrained by boundary conditions. The preliminary validation of the wheat grain model was based on literature data, and it revealed that the air supply method and the perforated area of silo walls significantly affected aeration efficiency. At a temperature of 35°C, the optimal results were achieved for a silo floor with 100 % perforated area and solid walls. At a lower temperature (10°C), grain moisture content also decreased, but the drying process was considerably longer. The model was highly consistent with the reference data, and the errors in the prediction of grain moisture content did not exceed 2 %.