Simulation of shrinkage effect in drying of food products in hot-air dryer

Abstract

Simulation of the hot-air drying period is very significant to decrease energy expenditure and increase food quality effect. In the present study, drying kinetics of three different foods (carrot, eggplant and cucumber) were investigated experimentally. At the end of the 180 minute drying process, the maximum change in moisture content was found to be in eggplant with 83%. The simulation model developed for hot-air drying was used to solve the heat and mass transfer equations which include shrinkage effect for food products. The shrinkage effect was obtained using the Arbitrary Lagrangian Eulerian method. At the end of the drying process, volume change for carrot, cucumber and eggplant were obtained as 55.7%, 55.7% and 68.7% respectively. On the other hand, the numerical model defines the internal moisture distributions of the food depending on the time. In this study, furthermore, empirical data were applied to different drying models. Statistical conclusions indicated that the Midilli model was the best to explain the drying behaviour for cucumber (R-2 = 0.99, SEE=0.0077, x(2) = 6.00x10(-5)) and eggplant (R-2 = 0.99, SEE=0.0169, x(2) = 0.0003). However, Wang and Singh model was found to be the most suitable model for carrot (R-2=0.99, SEE=0.0054, x(2)=2.95x10(-5)). The experimental data were compared with numerical results for the drying of carrots, eggplant, and cucumber. It was shown a very good agreement between numerical simulation and experimental solution.