Characterization of Pore Diameters in Highly Porous Media

2003 ◽  
Author(s):  
H. L. Pan ◽  
O. Pickena¨cker ◽  
D. Trimis
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Pore Diameter ◽  
Laminar Flame ◽  
Combustible Mixture ◽  
Critical Conditions ◽  
Flame Velocity ◽  
Geometrical Properties ◽  
Highly Porous

In this paper, a method for the experimental characterization of the equivalent pore diameter of highly porous open structures is presented. The commonly used characterization of such structures through geometrical properties like ppi number (porous per inch) and porosity proves to be not sufficient for the characterization of length scales related to heat and mass transfer. The procedure used here utilizes the quenching limits for flame propagation as characterization criterion. The determined equivalent pore diameter corresponds to the quenching diameter for a tube-geometry filled with the same combustible mixture. The quenching limit was determined by adjusting critical conditions, which are defined by a constant critical Pe´clet number comprising the laminar flame velocity instead of the flow velocity. Variations of oxygen content and air ratio were used in order to change the laminar flame speed and find the quenching limit for a given porous medium. The equivalent pore diameter determined with this method is a characteristic length scale of the porous medium geometry and is related to the heat transfer between the gas phase and the solid porous structure. The validation of the method was performed on sphere packings with well-documented properties. Several practically relevant highly porous media like foams and fabric lamellae structures were characterized and the results are discussed. Based on the effective heat conductivity (EHC) models of Zehner, Bauer and Schlu¨nder [1–3] for packed beds, an adapted model for foam structures was developed. The adapted model utilizes the equivalent pore diameters determined in the paper and predictions are presented.

Structure of Polymer Chains Confined in Vycor

1996 ◽  
Vol 464 ◽  
Author(s):  
Jyotsana Lal ◽  
Sunil K. Sinha ◽  
Loic Auvray
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Form Factor ◽  
Small Angle Neutron Scattering ◽  
Pore Diameter ◽  
Polymer Chains ◽  
Bulk Solution ◽  
Radius Of Gyration ◽  
Single Chain ◽  
Molecular Weights

ABSTRACTWe observe by Small Angle Neutron Scattering (SANS) the structure of polystyrene chains in semi-dilute solutions confined in model porous medium, Vycor. The size of the free polymer chains in solution is always larger than the pore diameter, 70 Å. The use of a suitable mixture of hydrogenated and deuterated solvents and polymers enables us to directly measure the form factor of one single chain among the others. The penetration of the chain in the porous media is almost complete for the concentration (Φ = 20%) and the range of molecular weights (35000 <M< 800000) used. The measured radius of gyration of confined chains is always smaller than the radius of gyration of free chains in the equivalent bulk solution.

CHARACTERIZATION OF POROUS MEDIA WITH GEOMETRICAL MULTIFRACTALS

Fractals ◽  
1993 ◽  
Vol 01 (04) ◽  
pp. 894-903 ◽  
Author(s):  
ANTOINE SAUCIER ◽  
JIRI MULLER
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Spatial Distribution ◽  
Multifractal Spectrum ◽  
Spatial Variations ◽  
Local Porosity

In a porous medium the local porosity often exhibits spatial variations. These variations can be characterized by a multifractal spectrum, as long as suitable scaling characteristics are present. We derive some of the properties of such geometrical multifractals, and discuss how the spatial distribution of a set is related to its multifractal spectrum.

Characterization of heat transfer in consolidated, highly porous media using a hybrid-scale CFD approach

2020 ◽  
Vol 149 ◽  
pp. 119201 ◽  
Author(s):  
Sebastian Meinicke ◽  
Konrad Dubil ◽  
Thomas Wetzel ◽  
Benjamin Dietrich
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Highly Porous

scholarly journals Prediction of Methane and Ethane Gas Hydrate Formation and Their Mixture in a Porous Medium

2019 ◽  
pp. 1-16
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Thermodynamic Modeling ◽  
Gas Hydrate ◽  
Pore Diameter ◽  
Laboratory Data ◽  
Hydrate Formation ◽  
Equilibrium Temperature ◽  
Formation Temperature ◽  
Gas Hydrate Formation

The purpose of this paper is to study the thermodynamic modeling of the conditions for methane and ethane gas hydrate formation and their mixtures in a porous and non-porous environment. In this paper, the Van der Waals- Platteeuw thermodynamic model was used for prediction of gas hydrate formation conditions. Also, the SRK and PTV equations of state were used for calculations of driving force. In this research, the results of thermodynamic modeling in a porous were compared with the non-porous environment and laboratory data in the literature. Studies have shown that the results of the modeling are in good agreement with the laboratory data and the percentage of errors is low. The results also showed that with increasing pressure of porous and non-porous media, the equilibrium temperature increases. In addition, the effect of the pore diameter of porous media on the results of modeling was investigated for methane, ethane and their mixtures during gas hydrates formation. The results showed that by increasing the pressure for any size of the pore diameter of the porous medium, hydrate formation temperature increases. In addition, by increasing the pore diameter of the porous medium, hydrate formation temperature methane, ethane and their mixture increase at a constant pressure. The results also showed that the equilibrium temperature of the non-porous medium is higher than the equilibrium temperature of the non-porous medium. This shows that the hydrate formation in the porous medium has a deterrent effect and leads to lower temperatures and higher temperatures conditions for gas hydrate formation. The results showed that by increasing the percentage of methane in a porous or non-porous medium, the temperature of hydrate formation of the binary gas mixture of methane and ethane decreases.

Conservative solute transport with periodic velocity and sinusoidal source concentration in semi-infinite porous media: An analytical solution

2014 ◽  
Vol 6 (1) ◽  
pp. 1024-1031
Author(s):  
R R Yadav ◽  
Gulrana Gulrana ◽  
Dilip Kumar Jaiswal
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Laplace Transformation ◽  
Seepage Velocity ◽  
Transformation Technique ◽  
Numerical Examples ◽  
One Dimensional ◽  
Porous Domain ◽  
Conservative Solute Transport ◽  
Source Concentration

The present paper has been focused mainly towards understanding of the various parameters affecting the transport of conservative solutes in horizontally semi-infinite porous media. A model is presented for simulating one-dimensional transport of solute considering the porous medium to be homogeneous, isotropic and adsorbing nature under the influence of periodic seepage velocity. Initially the porous domain is not solute free. The solute is initially introduced from a sinusoidal point source. The transport equation is solved analytically by using Laplace Transformation Technique. Alternate as an illustration; solutions for the present problem are illustrated by numerical examples and graphs.

Capillary Imbibition Dynamics in Porous Media

2014 ◽  
Author(s):  
Swayamdipta Bhaduri ◽  
Pankaj Sahu ◽  
Siddhartha Das ◽  
Aloke Kumar ◽  
Sushanta K. Mitra
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Paper Strip ◽  
Capillary Imbibition ◽  
Flow Physics ◽  
Fundamental Understanding ◽  
Paper Based Microfluidics ◽  
To Come

The phenomenon of capillary imbibition through porous media is important both due to its applications in several disciplines as well as the involved fundamental flow physics in micro-nanoscales. In the present study, where a simple paper strip plays the role of a porous medium, we observe an extremely interesting and non-intuitive wicking or imbibition dynamics, through which we can separate water and dye particles by allowing the paper strip to come in contact with a dye solution. This result is extremely significant in the context of understanding paper-based microfluidics, and the manner in which the fundamental understanding of the capillary imbibition phenomenon in a porous medium can be used to devise a paper-based microfluidic separator.

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