Research on the cooling of corn grain in the mound

Abstract

Two-stage drying is widely used in agriculture in Russia and abroad when grain is under-dried to condition humidity by several percent and left to dry by atmospheric air, thereby saving costs of heat. When using this method, there are questions about determining the minimum air velocity in the layer, the calculation of retention time before and during the ventilating process itself. For different thicknesses of the material layer, the retention time varies greatly - from 6 h to 24 h. This is due to the fact that the duration is usually set empirically by the increased or decreased moisture content during the process. Cooling duration is calculated from the recommended normative specific air supply to the bulk and its consumption per ton of cooled grain, which often leads to overestimated cooling duration. Therefore, the purpose of this work is to substantiate and calculate the permissible specific air supply, as well as the duration of tempering and cooling of grain. Minimum specific air supply during cooling of heated grain depends on the layer thickness, the coefficient of moisture evaporation and the logarithm of the difference between the relative humidity of moisture vapor on the surface of grain and air. The minimum duration of tempering of heated grain is caused by moistening its outer surface and depends on the coefficient of moisture diffusion, the radius of the grain, the thickness of the shell and the logarithm of the difference between the current and equilibrium moisture content. The duration of cooling of the embankment can be calculated according to the dependencies for drying grain at the actual values of air and embankment parameters. Economic studies have shown the admissibility of using the obtained dependencies for calculating the main parameters of the process without reducing the quality of grain.