Modeling Effective Moisture Diffusivity of Orange Slice (Thompson Cv.)

The present study was conducted to compute effective moisture diffusivity and activation energy of orange slices during convection drying. The thin-layer drying experiments were carried out at five air temperatures of 40, 50, 60, 70, and 80C, three air velocities of 0.5, 1.0, and 2.0 m/s and three orange slice thicknesses of 2, 4, and 6 mm. Results indicated that drying took place in the falling rate period. Moisture transfer from orange slices was described by applying the Fick's diffusion model. The effective diffusivity values were increased from 6.27 x 10-10 to 3.50 x 10-9 m2/s for the temperature range used in this study. An Arrhenius relation with an activation energy value of 16.47 to 40.90 kJ/mol and the diffusivity constant value of 7.74 x 10-7 to 3.93 x 10-3 m2/s were obtained. It was found that with increasing the temperature and air velocity the effective diffusivity increases while slice thickness showed no considerable changes on the effective diffusivity.