Modeling of the drying kinetics solar of gombo section

The objective of this work is the modeling of the drying kinetics of the gombo sections by using a solar drier. The objective of this work is to model the drying kinetics of okra slices using a hybrid solar dryer. The work focused on the kinetics of okra slices at different thicknesses (1cm, 1.5cm and 2cm), temperatures (40°C, 50°C and 60°C) and different air speeds (1m/s, 1 .5m/s and 2m/s). The methodology consisted in following water content okra section of time function. The driying curves obtained were modeled with six semi-empirical models by the nonlinear regression method with the validation criterion following : coefficient of determination (R^2), chi-square (χ^2 )andMean Square Error (RMES ).The diffusion coefficient was estimated from the simplified solutions of Fick's second law Two parameters were given: the energy of activation and the coefficient of diffusion. The results obtained show that mass diffusivity increases with the temperature and the thickness of the product. The coefficient of diffusion varies from 3.5.10 -8 to 5.88.10-7 m2/s, and the activation energy of 12.50kJ/mol with 54.82KJ/mol. The time of drying decreases with the increase in the temperature, and the speed of air and increases with the increase thickness of produit. The models of Demir et al., and Wang and Singh are most reliable to represent the water content reduced of the gombo according to time, therefore as well as possible simulate the kinetics of the gombo drying with for coefficients of correlation respective :R^2=0.99708,X^2=0.000467,RMES=0.0215 for Demir et al., and R^2=0.99527,X^2=0.00734,RMES=0.02289 for Wang and Singh.