Research
Mathematical Modeling of Thin-Layer Drying Behavior of Date Palm
The effect of microwave drying technique on drying kinetics of date palm was investigated. The results showed that the change of moisture ratio with drying time in the power density range from 4 to 9.5 W/g can be successfully described by Page model. Values of drying rate constant (k) were in the range of 0.052–0.142 (1/min) and the effective moisture diffusivities (Deff) of date range palm from 2.72×10−6 to 4.73×10−6 (m2/s). The values of k and Deff increased with the increase of power density. The power density dependence of the effective diffusivity coefficient was expressed by an Arrhenius type relationship. Activation energy for the moisture diffusion was determined as 3.908 W/g.
Mathematical modeling and thin layer drying kinetics of Carrot Slices
The thin-layer drying characteristics of carrot slices were investigated under four microwave powers; 200, 300, 400 and 500 W and slice thickness of 2.5 mm. Data were analyzed to obtain diffusivity values from the period of falling drying rate. Four mathematical models for describing the thin-layer drying behavior of carrot were investigated. The results show that the Midilli et al. is the most appropriate model for drying behaviour of thin layer carrot slices. An analysis of variance (ANOVA) revealed that microwave power significantly affected the drying time, drying rate, effective diffusivity and specific energy consumption. The effective diffusivity varied from 1.90×10−8 to 3.99×10−8 m2/s, and the activation energy was determined to be 36.40. Specific energy consumption values ranged 8.58 to 12.46 MJ/kg and the optimized specific energy consumption was obtained 540 W microwave levels.
