Numerical investigation into the aeration of grain silos

Abstract

The aeration of grain silos provides a convenient means of controlling temperature and moisture distribution in a silo. The moisture migration process is initiated by the presence of temperature gradients which causes natural convective air movement within the grain. By being able to predict the moisture and temperature behaviour during the grain aeration process, the grower will be able to produce a more efficient aeration process that minimises grain spoilage. The purpose of this project is to investigate the aeration characteristics of a grain silo using a Computational Fluid Dynamics package and develop an understanding of the complexities involved with the modelling of grain ecosystems with regard to air movement, moisture migration and temperature distribution within the grain. More specifically, this project seeks to investigate numerically the effect of different parameters of silos (size, shape, material, type or design and aeration rate) on the temperature distribution in the stored grain, under a variety of seasonal conditions. The computational fluid dynamics software (Fluent 6.0) was used to investigate these parameters and provided results in the form of contour plots (temperature and pressure) and velocity vector plots. The CFD package provides a strong basis for the analysis of packed beds. However, further attention needs to be paid to the reactions within the intergranular environment to allow the program to produce results of a higher degree of accuracy.