Using of Semi-Empirical Models and Fick’s Second Low for Mathematical Modeling of Mass Transfer in Thin Layer Drying of Carrot Slice

Drying behavior of carrot slices were studied at 200, 300, 400 and 500 W for constant sample thickness (5mm) in a microwave dryer. By increasing the microwave output powers (200-500 W), the drying time decreased from 17.5 to 9.5 min. The drying process took place in the falling rate period. Six mathematical models for describing the thinlayer drying behavior of carrot slices were investigated. The models were compared based on their coefficient of determination (R2), root mean square error (RMSE) and reduced chi-square (χ2) values between experimental and predicted moisture ratios. The results show that the Midilli model is the most appropriate model for drying behaviour of thin layer carrot slices. Moisture transfer from carrot slices was described by applying the Fick's diffusion model, and effective moisture diffusion coefficients were calculated. A third order polynomial relationship was found to correlate the effective moisture diffusivity (D eff ) with moisture content. The effective moisture diffusivity increased with decrease in moisture content of carrot slices. Average effective moisture diffusivity increased from 6.33×10 -9 to 1.14×10 -8 m 2 /s with increasing the microwave power.