An Investigation of the Combined Heat and Mass Transfer Processes in the Drying of Hygroscopic Porous Media with Two Disparate Length Scales

A mathematical model describing the drying process in a hygroscopic porous medium with two disparate length scales is formulated. The mathematical model is used to identify the important dimensionless parameters appearing in the problem; and, a parametric study is performed to determine the effects of varying these parameters on the drying process. Of particular interest in this study is to apply the model to the drying of large, round hay bales. Therefore a discussion of how the results of the parametric study impact on the efficient use of a hay drier is also presented.

The results from the parametric study indicate that the drying times of a porous medium may be decreased by increasing the Reynold's number, increasing the inlet air radius of the drier, decreasing the overall aspect ratio of the porous structure, and decreasing the Kossovich number. In addition, it is shown that the velocity distribution through the porous medium plays a significant role on the drying behavior. It was concluded the greatest potential for improving the drying time for hay bales was to decrease the aspect ratio of the bale.