Investigation of the drying behavior of ginger in cyclone type dryer

In this work, the thin layer drying behavior of ginger slices in a cyclone type convective dryer were investigated. Drying experiments were carried out at four different drying temperatures (40, 50, 60 and 70 °C) and three drying air velocity (0.8, 1.5 and 3 m/s). In order to obtain drying data, the changes in the mass of ginger slices were recorded as well as the drying air properties. The effects of drying temperature and air velocity on the drying rate and moisture ratio, diffusion coefficient, activation energy and convective heat transfer coefficient of the ginger slices were investigated. The moisture ratio data were fitted to the twelve mathematical models and performance of these models was determined by correlation coefficient (R), reduced chi-square (χ2) and root mean square error (RMSE). For the thin layer drying of ginger slices, the Midilli and Kucuk model was the best descriptive model. From the Midilli and Kucuk model for ginger slices, it was determined that R=0.95432, χ2=0.008339581, RMSE=0.090408072. The moisture transfer from the ginger slices occurring during the falling rate period of drying was characterized by determining experimentally the diffusion coefficient into the air. The diffusion coefficient values of ginger slices were changed in the range of 2.807x10-10-6.977x10-10 m2/s. The average convective heat transfer coefficient values of ginger slices were varied in the range of 0.33-2.11 W/ m2˚C. Key words: Thin layer drying models, diffusion coefficient, convective heat transfer, ginger