20 th European Symposium on Computer Aided Process Engineering – ESCAPE20 S. Pierucci and G. Buzzi Ferraris (Editors) © 2010 Elsevier B.V. All rights reserved. Transport Phenomena Modeling During Drying of Shrinking Materials Maria Aversa, Stefano Curcio, Vincenza Calabrò, Gabriele Iorio Department of Engineering Modeling, Ponte P.Bucci - Cubo 39/c , University of Calabria, Rende (CS) 87030, ITALY maria.aversa@unical.it; stefano.curcio@unical.it; vincenza.calabro@unical.it; gabriele.iorio@unical.it Abstract Different kind of materials are usually submitted to drying. In some cases the aim is to decrease their transportation costs in some others to preserve materials from deterioration. The latter is the case of foods drying. Foods usually exhibit changes in shape and dimensions (known as shrinkage) during drying caused by water loss. The aim of the present work is the modeling of the transport phenomena involved in drying process accounting for also the shrinkage effects. The simultaneous transfer of momentum, heat and mass occurring in a convective drier where hot dry air flows about the food sample have been modeled. The system of non-linear unsteady-state partial differential equations modeling the process has been solved by means of Finite Elements Method coupled to the ALE (Arbitrary Lagrangian Eulerian) procedure that, by a proper modification of integration domain, accounts for shrinkage effects. The model proposed is suitable for industrial equipment optimization. Keywords: Food drying, Transport phenomena, Finite Elements Method, Process Modeling, Shrinkage 1. Introduction In a previous paper (Curcio, Aversa, Calabrò, Iorio 2008) the authors of the present work formulated a theoretical model describing the transport phenomena involved in food drying process. The attention was focused on the simultaneous transfer of momentum, heat and mass occurring in a convective drier where dry and hot air flowed, in turbulent conditions, around a wet and cold food sample with a low porosity. Moisture transport inside food with low porosity, where inner evaporation can be neglected, (May & Perré 2002), was modelled by an effective diffusion coefficient of water in the food, thus not distinguishing between the actual transport of both liquid water and vapour within the food structure. Porous foods are hygroscopic materials that contain both bound and free water (Datta 2007 I). Actually during drying of food with high porosity, water evaporation takes place inside the food as well as at the food external surface. Moreover, although evaporation takes place inside the food, the transfer rates occurring at air/food interface are strongly dependent on the drying air velocity field existing in the drying chamber and, particularly, in the boundary layers developing close to the food surfaces exposed to air. For this reason, to improve the precision of the model, in particular close to the solid surfaces, the k-ω model (Wilcox 1998) has been used in the present paper to calculate drying air velocity field and to describe the momentum transport in turbulent conditions. The aim of the present work is to adopt a conservation-based approach to develop a multiphase transport model so to describe convective drying process. The model is based on conservation of liquid water,