The purpose of this review paper is to present the results of laser anemometry and flow visualization studies of the flow of liquids in porous structures. Three dimensional velocity profiles and movies of dye streaklines will be shown. The porous media consisted of plexiglas spheres in a hexagonal packing and glass and plexiglas rods arranged in a complex, fixed three dimensional geometry. The liquids used were water, silicone oils, Sohio MDI-57 oil and mineral seal oil. The Reynolds number based on average pore size and average pore velocity ranged from 0.16 to 700.

A New Look at Porous Media Fluid Mechanics — Darcy to Turbulent

Some structural properties of packed bed systems on both the local and overall scales which are available in the literature and of interest in chemical engineering applications are discussed. Regular and random packings of uniformly sized spheres are initially analyzed as a basis for the later examination of the more general case of random packed beds containing particles of various sizes and shapes, with or without restraining surfaces.



On discute, sur une echelle locale et globale, certaines proprietes structurales deg systemes a base de lits garnis qu'on mentionne dans des ecrits et qui sont interessantes a cause de leurs applications en genie chimique. On analyse d'abord des garnitures regulieres et irregulieres de spheres aux dimensions uniformes, et ce comme base d'un examen ulterieur du cas des lits qui sont garnis irregulierement, continnent des particules de dimensions et formes diverses et possedent des surfaces restreintes on non.

Structural properties of packed beds — A review

The present work centers around the numerical simulation of forced convective incompressible flow through porous beds. Inertial as well as viscous effects are considered in the momentum equation. The mathematical model for energy transport was based on the two-phase equation model, which does not employ local thermal equilibrium assumption between the fluid and the solid phases. The transport processes for two different types of boundary conditions are studied. The analysis was performed in terms of nondimensional parameters that successfully cast together all the pertinent influencing effects. Comparisons were made between our numerical findings and experimental results. Overall, the comparisons that were made for the constant wall heat flux boundary condition display good agreement.

Effects of boundary conditions on non-Darcian heat transfer through porous media and experimental comparisons

A simple model for estimating the emissivity of the surface of a powder bed by knowing only the bed porosity and its solid emissivity is presented. Estimates by the model are compared with experimental measurements for powder beds of alumina, silicon carbide, and iron. Agreement within the uncertainty of the measurements of ±10% is obtained. A view factor that adopts the predicted emissivity of the powder beds into its term is suggested for the calculation of the conductivity by radiation. For the prediction of the thermal conductivity of the powder beds, the authors compared the existing models in literature. They rederived the Zehner-Schlunder equation (1970) and made some modifications to it. Comparison of predictions by this equation with 424 measured values shows the predictions to be accurate to within a ±30% relative error.

J. J. Barker

Papers

Heat transfer in packed beds