Fatemeh Nadi - Agriculture Machinery Mechanics Dept., Islamic Azad University, Azadshahr Branch

Drying conditions affect the quality of dried apple slices. Therefore, an accurate description of the drying rate is required. In this study, a two-dimensional finite element (2-D FE) model was developed in order to to simulate moisture diffusion in apple fruit during vacuum drying. The diffusivity of apple used in this simulation was determined experimentally. For experiment, thin layer apple slices, ‘Golden delicious’ variety, was dried at drying air temperatures 50, 60 and 70°C with three replications at a absolute pressure of 20 kPa. Moisture diffusivity of apple fruit was determined by minimizing the sum of squares of the residuals between experimentally determined and numerically predicted data. A commercial FEM package, called FEMLAB was used to simulate the finite element model and it satisfactorily predicted the moisture diffusion during drying. Moisture ratio profiles of the apple fruit were also predicted and the profiles gave accurate pictures of the movement of moisture inside apple fruit during drying. This model can be used to provide information on the dynamics of moisture movement without the need for measurements and can also be used to provide design data of dryers.

2-D, Simulation, Mass Transfer, Finite Element, Vacuum Drying, Apple