X ray CT image analysis to determine air flow path in grain bulks

Airflow resistance in grain bulks is a critical factor for the design of drying and aeration systems. Airflow resistance is required to predict uniformity of airflow during aeration and to determine duct designs for adequate ventilation. Previous studies have determined that the airflow resistance in the vertical direction is 30 to 40% higher than in the horizontal direction in cereal grain bulks. This may be caused by the tendency of grain kernels to lie with their major axes being nearly horizontal during filling thus creating narrower air flow paths in the vertical direction than in the horizontal direction. In this study, airflow paths along the vertical and horizontal directions in wheat samples were determined using X-ray computer tomographic (CT) scan images. The CT scan images were analyzed using image processing algorithms and air flow paths were estimated. Images were also analyzed to determine the orientation, length and area of airflow paths. It was determined that the area of airflow path along the horizontal direction was about 9% less than in the vertical direction. This difference in airflow path might partially contribute to the difference in airflow resistance along vertical and horizontal directions in grain bulks.