EXPERIMENTAL INVESTIGATION OF THE DEHYDRATION KINETICS OF WHITE YAM (DIOSCOREA ROTUNDATA) USING A REFRACTANCE WINDOWTM DRYER
The objective of this study is to investigate the dehydration characteristics of yams slices at different drying temperatures and for different thicknesses of yam slices. Yam slices 1.5, 3.0, and 4.5 mm thick were dehydrated in a laboratory-scale Refractance WindowTM dryer at 65, 75, 85, and 95oC. During the drying operations, moisture content data were recorded. The experimental moisture content data were fitted into empirical and semi-theoretical thin-layer drying models. For the process conditions studied, the drying data fitted all the thin-layer drying models considered in this report, with a correlation coefficient greater than 98%. However, the Haghi and Ghanadzadeh model gave a higher correlation than the other models implying that the model predicts the drying kinetics of yam better than other models. The data was also used to plot the drying curve and the drying rate curve. The drying times to dehydrate the yam slices to a moisture ratio of 0.11g-water/g-solid varied between 25 to 320 minutes. The drying times were observed to decrease as the temperature increased for a given slice size. Also, the drying times increased with slice size for a given temperature. This study was performed to facilitate the understanding of the dehydration characteristics of the Refractance WindowTM (RW) drying operations for yam slices, with the intentions of designing, modelling, and operating a continuously operating RW dryer.