Simulation of food drying: FEM analysis and experimental validation

The aim of the present work is the formulation of a theoretical model describing the simultaneous transfer of momentum, heat and mass occurring in a convective drier where hot dry air flows under turbulent conditions around a food sample. The proposed model does not rely on the specification of interfacial heat and mass transfer coefficients and, therefore, represents a general tool capable of describing the behavior of real driers over a wide range of process and fluid-dynamic conditions. The system of non-linear unsteady-state partial differential equations modeling the behavior of a cylindrical-shaped vegetable sample in a drier, has been solved by using finite elements method. It has been observed that air characteristics influence drying performance only when external resistance to mass transfer is the rate controlling step. An experimental study was undertaken which shows very good agreement between model predictions and experimental results.