Combined conduction and radiation heat transfer in porous media

Porous media heat transfer has long been investigated and studied in many of the years, regarding to the numerous applications in the manufacturing industry. In a porous media, conduction is the dominant in the solid, which energy is transferring across the contact area by diffusion. Radiation is also effective in the high temperature condition, which the energy is transporting along the voids. Convection can always be neglected unless there is a convective fluid like water flowing inside the domain and help supplement the energy transfer. In usual practice, scientists are usually focused on one of the heat transfer mechanism on the research study, as they would like to distinguish one mechanism from the others. Therefore, the study on a combined heat transfer will be demanding and challengeable, and the combined conduction and radiation in porous media is the current subject. The work of this thesis is a numerical simulation in combined conduction and radiation heat transfer for packed beds in the microstructure scales. From the objectives, four individual sections were divided and focused. The first section is a study on modeling porous media, which two major algorithms have been developed for packing spheres into a homogeneous volume with controlled coordination number (CN) and contact radii ratio (AC). With the packed porous media, radiation modeling was achieved in the second part to compute the radiant transfer coefficient, temperature, as well as the radiant conductivity. Next was followed by a validation plan which different radiation approaches were quoted to benchmark the current radiation model. In the last section, a constriction resistance scheme was applied in the conduction subject. Combining with the radiation model, a new algorithm was developed to simulate the combined conduction and radiation heat transportation. The study of the combined heat transfer focused on the effects of microstructure networks, surface emissivity as well as different boundary conditions. Numerous results have been obtained regarding to the subject and have been validated