Effective Moisture Diffusivity and Activation Energy Estimation of Cucumber Fruit Slices Using a Refractance WindowTM Dryer
This paper presents an estimation of the effective moisture diffusivities and the activation energy of cucumber fruit slices by studying the effect of temperature on the drying kinetics. A laboratory scale Refractance WindowTM dryer was used to obtain dehydration data for cucumber fruit slices. Experiments carried out on 3 mm thick cucumber fruit slices with water temperatures in the dryer at 65 oC (338K), 75 oC (348K) and 85 oC (358K) were performed. The experimental drying data were fitted to 8 thin layer drying models to select the most appropriate drying model. The Haghi and Ghanadzadeh model was determined to be the most suitable for the process conditions studied. Fick’s second law was used to calculate the effective moisture diffusivity. The moisture diffusion coefficient varied between 1.94 x 10-9 m2s-1 and 2.54 x 10-9 m2s-1 for the process conditions studied. The activation energy was estimated using the Arrhenius equation and for the given temperature range. The corresponding activation energy was calculated to be 13.55kJ/mol. A knowledge of the effective moisture diffusivities and activation energy of the cucumber fruit slices, when determined using the Refractance WindowTM drying technique will aid in understanding the design, analysis, and optimisation of such equipment for the drying of food.