Modeling of Drying Kinetics of Paddy (cv. Fajer) using a Thin-layer Dryer

Rice is one of the most widely human consumed agricultural products. For a prevention or diminishing of rice cracking in its milling process, precision control of drying conditions is indispensable. In this research, a thin layer experimental dryer is employed to obtain paddy’s drying kinetics. Drying experiments were conducted at five inlet temperatures of drying air of 30, 40, 50, 60 and 70 °C and four air velocities of 0.25, 0.5, 0.75 and 1 m/s, with three replications. The initial moisture content was about 27% (d.b.) at the start of all the runs. Equilibrium moisture content was attained through a use of conventional empirical isotherm equations. Drying curves of moisture ratio vs. time as well as drying rate vs. time were plotted from the obtained experimental data. Drying curves obtained from the experimental data were fitted to eight different empirical thin layer models and compared with the help of three statistical parameters (R2, RMSE and). Results show that approximation of diffusion model predicts moisture change in drying with a higher accuracy in comparison with the other models. The coefficient of determination (R2) for this model at the inlet drying air temperatures of 30, 40, 50, 60 and 70 °C were 0.999, 0.999, 0.999, 0.998 and 0.996, respectively. These results indicate that an approximation of diffusion can very accurately model the moisture ratio vs. time variations of paddy, and they as well indicate the applicability of thin-layer dryer for experimental works.