Experimental and Modeling of Tomato Slices Sorption Isotherms and Thin Layer Drying Kinetics for a Solar Drying Plant Design

Document Type : Research Article

Authors

Applied Thermodynamic Laboratory, National School of Engineers of Gabes Tunisia, Medina Street 6029, University of Gabes, TUNISIA

Abstract

In the present work, the sorption isotherms of tomato slices (TS) are obtained by the gravimetric method at different temperatures (50, 60, and 70 °C). After fitting the desorption curves, the Guggenheim-Anderson-de Boer (GAB) model is chosen as the most appropriate model for the experimental data of tomato slice desorption isotherm.  The isosteric heat of desorption is then determined by the Clausius-Clapeyron equation. Modeling of the convective drying kinetics is performed by experimental study of the effects of aerothermal conditions, such as temperature and hot air velocity. The drying characteristic curves are then fitted using MATLABR 2013 nonlinear regression- functions.  The parabolic model was found to be the most appropriate model for the experimental results of kinetic drying of tomato slices, with the highest R² correlation coefficient average value (0.9983) and the lowest RMSE average value (0.0119). The effective moisture diffusivity and the activation energy are tested by the second Fick's law. The values of effective moisture diffusivity ranged from 2.028 10-7 to 5.071 10–7 m²/s. The activation energy was calculated to be 42.140 kJ/mol.

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