1. Multiphase Porous Media Transport in Apple Tissue During Drying
C. Kumar1, G. J. Millar1, T. W. Farrell2, M.A. Karim1 1Chemistry Physics and Mechanical Engineering, Queensland University of Technology
2Mathematical Science, Queensland University of Technology
Introduction
Multiphase porous media model in food processing have been proven to be very effective and accurate in wide range of applications such as frying, microwave heating, puffing, baking, meat cooking. However, application of multiphase models in drying is very limited. This study aims to develop a multiphase porous media model for heat and mass transport during drying. The model considered an explicit non-equilibrium formulation for evaporation and variable thermo-physical property of the product during drying. Finite Element Method (FEM) based software COMSOL multiphysics was used to solve the equations. The model was compared with experimental data and good agreement was found.
Results:
Fig 1: Predicted and experimental moisture content Fig 2: Centre and surface temperature from model
Fig 3: Distribution of moisture (water saturation) with time Fig 3: Distribution of vapour (mass fraction) with time
Water fluxes: Vapour fluxes:
Problem formulation
Governing Equations
Liquid water:
Water vapour:
Heat transfer:
Evaporation:
Conclusion
Multiphase porous media model for drying is developed and validated
The evaporation rate decrease with moisture content and higher evaporation zone moves towards the center as surface get dried
Capillary flux is higher at about 0.5–1.0mm beneath the surface and this peak moves towards the core with time
Vapor fluxes from both sources are mainly occurring near the surface with nearly zero in the core region
The model extended for Intermittent Microwave Convective Drying (IMCD)