THE DRYING CHARACTERISTICS AND MODELING OF PEPPERCORN DRYING IN SPOUT FLUID BED DRYER

This article aimed to examine the characteristics and to create a model of peppercorn drying in a spout fluid bed dryer. For describe the thin layer of peppercorn drying, different drying conditions selected three levels of drying temperatures (70, 80 and 90oC), two levels of spout air flow rate (120 and 160 m3 /hr) and constant bed height of 15 cm. The fluidized air flow rate fixed at 63.6 m3 /hr, that its value of minimum fluidized velocity. Mathematical models were used to analyze the characteristic of peppercorn drying. Two statistical indices involving the coefficient of determination (R2 ) and root mean square error (RMSE) applied used for finding the optimum model. Results indicated that drying temperature and spout air flow rate affected the drying kinetic of peppercorn since increasing the level of both parameters resulted in decreasing drying time, specific energy consumption and L* , a * and b* values. For the mathematical model, the optimal model for explaining the drying kinetic of peppercorn was the page model due to the statistical indices gave the best value. In parts of the calculation of moisture diffusivity values, the values were achieved between 1.68  10-7 to 5.54  10-7 m 2 /s for different drying conditions. The activation energies were 41.94 and 49.13 kJ/mol at spout air flow rate of 120 and 160 m 3 /hr, respectively.