Summary: The quality of cereal grains in storage will deteriorate to an unacceptable level if they are not kept dry and cool. To model the drying and cooling process, an accurate knowledge of the airflow distribution is required. In this paper, the equations used to model the air velocity are analyzed.
To study the flow of air through a typical drying system for stored grain, a two-dimensional rectangular bin is considered, with a single source of air on the bin floor. Two paths of study are undertaken: the first is a linear analysis for low velocities, and followed on from this is a nonlinear approach for larger velocities. The linear analysis is used to study a bin with a semi-infinite height, and the drying pattern is studied in this bin using the air traverse time. Then bins with a finite height are analyzed; it is shown that, for tall enough bins, the semi-infinite solution is accurate enough. A perturbation analysis is used to study the semi-infinite bin when the air velocity is too large for the linear analysis to be accurate. It is shown that the effect of the nonlinearity is to move the air away from the high-velocity regions towards the areas of lower velocity.