This study aimed to describe the behavior of ginger, and to predict its water content, during artificial drying under four temperatures (60 oC, 80 oC, 100 oC, 120 oC). Experiments were carried out on ginger using a DRY-Line type oven. The obtained data was fitted using 4 semi-empirical thin layer drying models. Among the semi-empirical models considered, the diffusion approach model was chosen as the most appropriate model to describe the behavior of ginger. For the different temperatures, he presented respectively the coefficients (r) of 0.9970; 0.9974; 0.9949 and 0.9942; the coefficients Chi-square (χ²) of 4.0306 X 10-6, 3.7015 X 10-7; 1.6387 X 10-7 and 1.3637 X 10-6 and Root Mean Square Errors (RMSE) of 3.5851 X 10-4; 1.1415 X 10-4; 9.2226 X 10-5 and 2.6604 X 10-4 for the four temperatures. The diffusion coefficient varies from 9.585 X 10-9 to 3.466 X 10-8 m2/s and strongly depends on the drying temperature. The activation energy is estimated at 24.188 kJ/mol.
The aim of this study is to compare a greenhouse solar drying simulated by a developed numerical model, with the actual experimental drying of cocoa beans. Thus, using multiphysical models (based on conservation laws of energy, mass and momentum within the dryer and beans), it was possible to simulate the greenhouse drying behavior of the beans. The resolution of the developed equation system was done using the finite element method of COMSOL Multiphysics 4.0 software. For the validation of the numerical model, an experimental study has been developed at the designed dryer. In this study, a drying operation of cocoa beans was conducted. The characteristics of the drying air (temperature, relative humidity and speed) as well as the mass of the beans were regularly determined over time. The results indicate that, in general, there is good agreement between the experimental results and the simulated results (R close to unity). This allows a validation of the mathematical model of the drying of cocoa beans within the greenhouse type solar dryer used.
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