Modeling Transport in Porous Media With Phase Change: Applications to Food Processing

Abstract

Fundamental, physics-based modeling of complex food processes is still in the developmental stages. This lack of development can be attributed to complexities in both the material and transport processes. Society has a critical need for automating food processes (both in industry and at home) while improving quality and making food safe. Product, process, and equipment designs in food manufacturing require a more detailed understanding of food processes that is possible only through physics-based modeling. The objectives of this paper are (1) to develop a general multicomponent and multiphase modeling framework that can be used for different thermal food processes and can be implemented in commercially available software (for wider use) and (2) to apply the model to the simulation of deep-fat frying and hamburger cooking processes and validate the results. Treating food material as a porous medium, heat and mass transfer inside such material during its thermal processing is described using equations for mass and energy conservation that include binary diffusion, capillary and convective modes of transport, and physicochemical changes in the solid matrix that include phase changes such as melting of fat and water and evaporation/condensation of water. Evaporation/condensation is considered to be distributed throughout the domain and is described by a novel nonequilibrium formulation whose parameters have been discussed in detail. Two complex food processes, deep-fat frying and contact heating of a hamburger patty, representing a large group of common food thermal processes with similar physics have been implemented using the modeling framework. The predictions are validated with experimental results from the literature. As the food (a porous hygroscopic material) is heated from the surface, a zone of evaporation moves from the surface to the interior. Mass transfer due to the pressure gradient (from evaporation) is significant. As temperature rises, the properties of the solid matrix change and the phases of frozen water and fat become transportable, thus affecting the transport processes significantly. Because the modeling framework is general and formulated in a manner that makes it implementable in commercial software, it can be very useful in computer-aided food manufacturing. Beyond its immediate applicability in food processing, such a comprehensive model can be useful in medicine (for thermal therapies such as laser surgery), soil remediation, nuclear waste treatment, and other fields where heat and mass transfer takes place in porous media with significant evaporation and other phase changes.

Effect of Temperature Distribution on Predicting Quality Of Microwave Dehydrated Food

“…The cell membrane is destroyed when it is processed at a high temperature. When the drying temperature is high, cell membranes rupture and release water into the extracellular space and therefore the transport of water to the outside occurs predominantly through the extracellular space (Halder, Dhall, & Datta, 2011). Therefore, temperature distribution is revealed to be influential for both the appearance and the structure of dried food materials.…”

On the capacity of a crust–core model to describe potato deep-fat frying

“…Yamsaengsung and Moreira (2002a), assumed that the temperature of the product does not increase until it reaches a very low-moisture content because of the large latent heat contribution compared to the rate of heat transfer from the oil to the food surface and so neglected the convective heat transfer term during this period. Halder et al (2011) took into account that h varies with time but they used the experimentally determined by Hubbard and Farkas (2000a) h values, ignoring the influence of frying conditions (e.g. the oil bath temperature profile) on h values.…”

“…The most sophisticated frying models are based on the theory of heat and mass transfer in porous media (Halder, Dhall, & Datta, 2011). The sophistication of these models goes as far as to include the volume transformation (potato shrinkage effect) at several levels of approximation: from complete consideration into the governing equations (Yamsaengsung & Moreira, 2002a, 2002b to complete ignorance recalling the lack of corresponding data (Ni, Datta, & Torrance, 1999).…”

Modeling and Validation of Microwave Ablations With Internal Vaporization

“…As liver tissue is being heated from microwave energy, tissue water undergoes a phase change to gas and can be transported through the porous matrix. Therefore, a numerical description of microwave ablation may be developed using established techniques for heat and mass transport in porous media [9]. …”