COMPUTATIONAL FLUID DYNAMICS (CFD) ANALYSIS OF AIR FLOW UNIFORMITY IN A FIXED-BED DRYER FOR MEDICINAL PLANTS

In fixed-bed dryers, product quality and dryer performance particularly depend on the homogeneity of airflow distribution rather than in continuous dryers. Aerodynamically unfavourable designs often cause uneven drying. The arrangement of the fans, the geometric design of the plenum chamber and drying grate as well as the flow rate of the drying air decisively influence the uniformity of flow profile. To improve the airflow distribution at an industrial fixed-bed dryer for medicinal plants, extensive network measurements were performed over the empty drying grate as well as several CFD simulations by using ANSYS CFD®. Based on it, the design of the flow directing baffles in the plenum chamber between ventilator and dryer was analysed. As a result, the optimal alignment of the baffles was attained and tested. Thereby, the airflow distribution was considerably homogenized.