Porous multiphase approach for baking process – Explicit formulation of evaporation rate

A multiphase model for simultaneous heat and mass transfer in porous medium was developed to simulate the baking process of a bread product. The model was based on Fourier’s law for conductive heat transfer and Darcy’s and Fick’s laws for mass transfer of liquid (water) and gas (water vapour and CO2) phases. Explicit formulation was adopted for the evaporation rate allowing direct solution of the system of equations. The use of the non equilibrium approach, allowed the implementation of the model in commercial software. Numerical Finite Element Method (FEM) scheme was used to solve the equations. The model was compared with experimental results reported in literature. Results show a good agreement between experimental and numerical results. Sensitivity analysis of the effect of the evaporation rate constant and process operating conditions on the temperature and moisture content were conducted and showed that the baking process was affected mainly by the convective heat transfer and the product initial moisture characteristics.