MODELING SIMULTANEOUS SHRINKAGE AND HEAT AND MASS-TRANSFER OF A THIN, NONPOROUS FILM DURING DRYING

Thin films of food products have long been dried commercially but the thin film drying process is not well understood. Modeling of a drying system is essential for understanding and improving it. A theoretical model for predicting the drying rate of thin films of nonporous foods was proposed, developed and evaluated. The model simultaneously considered shrinkage and heat and mass transfer within thin films dried on a surface with given boundary conditions. A finite element formulation of the model was used to develop numerical solutions of two governing equations. Starch was selected as a representative material for drying tests. Experimentally determined drying curves of modified corn, potato and rice starch films were compared to model predictions. The technique was useful in explaining the complex relationships of temperature, moisture and thickness profiles of drying films.