Kinetics of spouted-bed drying of barley: Diffusivities for sphere and ellipsoid

A study was performed to observe the drying kinetics of barley dried in a spouted-bed drier and to study the influence of the shape of a kernel assumed in the model on the estimated value of effective moisture diffusivity. Significant differences were observed in the moisture diffusivities of barley between temperatures applied and it ranged from 1.39 × 10−10 m2/s at 33 °C for ellipsoidal geometry to 5.31 × 10−10 m2/s at 56 °C for sphere. The model used has great potential and it is accurate and efficient to simulate moisture diffusion phenomena during drying of ellipsoidal-shaped solids, including spheres as a limit case. The results proved that using the proper geometry of a solid if of a fundamental importance for the purpose of determination its moisture diffusivity. It was also shown that using spherical geometry for modeling drying processes of grain is faulty if high accuracy of the results is expected.