Multiphase heat and mass transfer with large deformation in porous medi

Multiphase heat and mass transfer in porous media coupled with large deformation has many practical applications, such as food processing and soil science. Water evaporation, a complex phenomenon in hygroscopic materials, usually occurs in these processes and influences both transport and deformation. Most previous transport models have not considered the coupling between transport and large deformation due to the significant complexity. This study is intended to model the interacting deformation and heat and mass transfer process.;In this work, modeling of water evaporation in hygroscopic materials is reviewed first. A commonly used model consisting of water diffusion and heat conduction is shown to be incapable of modeling water evaporation. The role of water-vapor equilibrium state in modeling of transport in a hygroscopic material is discussed, followed by an equilibrium model and a non-equilibrium model for water evaporation, both of which assume constant pressure in the material.;A fully coupled model is then developed for transport and large deformation in porous media. Transport governing equations are based on mass and energy conservations, using the equilibrium approach for evaporation. Phases present include solid, liquid water, water vapor and air. Mechanics formulation takes updated Lagrangian format. The material is treated as viscoelastic and geometric nonlinear effect is included. The coupled transport and deformation model is solved using the finite element method. Special considerations are made on the conservation and numerical oscillation issues.;The model is applied to several computing examples. It is found that large deformation influences transport greatly in porous media through transport property and dimension changes so that transport and deformation should be modeled simultaneously.;Finally, the model is applied to the bread baking process in which the air transport is replaced with CO2 transport, the latter being generated by the baking process. Baking experiment is carried out to assist and compare with the modeling. To match the experimental observations, vapor pressure used in modeling needs to be lower than the measured equilibrium vapor pressure. The modeling shows that the final shape of the bread is mainly determined by gravity, mechanical properties and CO2 generation below 70°C. Heat transfer is enhanced by water evaporation-condensation. Baking temperatures higher than normal lead to smaller volume expansion due to early setting of the material. Using this model enables us to study the influence of processing factors such as mode of heating or heating temperature on the final outcome of the baking process such as volume expansion.