2 edition of variation of Knudsen diffusional coefficients with bed porosity. found in the catalog.
variation of Knudsen diffusional coefficients with bed porosity.
Samuel Kayode Adeshipo
in Bradford University
Written in English
|The Physical Object|
|Number of Pages||163|
Start studying ES. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Start studying Water Cycle, Porosity, Permeability, Capilarity. Learn vocabulary, terms, and more with flashcards, games, and other study tools.
VELOCITY-POROSITY RELATIONSHIP. The Shikoku Basin and Nankai accretionary prism sediments have been well imaged using seismic reflection methods (Bangs et al., ; Moore et al., ). Seismic velocity data are important for providing information about the large-scale structure of the prism. cell method for determining diffusion coefficients is still commonly used due to its simplicity and low cost. The method has a number of limitations, but remains an excellent choice for aggressive solutions that cannot be easily tested with interferometric methods. Stokes2 introduced a graphical method for extracting differential diffusion.
Handbook of Solid State Diffusion, Volume 1: Diffusion Fundamentals and Techniques covers the basic fundamentals, techniques, applications, and latest developments in the area of solid-state diffusion, offering a pedagogical understanding for students, academicians, and development engineers. Both experimental techniques and computational methods find equal importance in the first of this two. extremely low values whereas a slight variation in this parameter can lead to significant variation in UCS which can cause serious disruption of engineering designs. The establishment of a relationship between the two important parameters of bulk density and porosity will, .
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Types of porosity • bed porosity and particle porosity have to be differentiated. Effective diffusion coefficients • diffusional flow in the pores may be described by an effective diffusion coefficient time variation allows a distinction between individual and different. The Knudsen number is a good measure of the relative importance of Knudsen diffusion.
A Knudsen number much greater than one indicates Knudsen diffusion is important. In practice, Knudsen diffusion applies only to gases because the mean free path for molecules in the liquid state is very small, typically near the diameter of the molecule itself.
Types of porosity • Difference between bed porosity and particle porosity • Bed porosity (or void fraction) ε B is defined as the volume of voids per volume of reactor • The pellet void fraction or porosity is denoted by εand ε= ρ P * V g (ρ P effective particle density, V g pore volume) Jakubith.
Results of various authors on the average porosity of different shapes of grains (spheres, cylinders, lumps, Rashing rings) are codified, and relationships are derived between the porosity of fixed granular bed and the ratios of vessel diameter to grain diameter and the shape of the grains.
A formula is proposed for engineering evaluation of bed porosity, the accuracy of the calculation from Cited by: Determination of the effective diffusion coefficient in porous media including Knudsen effects Article (PDF Available) in Microfluidics and Nanofluidics 4(3) · March with 2, Reads.
b Knudsen diffusion in porous solid: When the molecular mean free path is much larger than the diameter of the pore in which the diffusing molecules reside, the molecules collide with the wall rather than colliding with other molecules.
This mode of transport is known as Knudsen diffusion. Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and %.
Strictly speaking, some tests measure the "accessible void", the total amount of void space accessible from the surface (cf. closed-cell foam). in the bulk and Knudsen regimes may have its origin in the different influence of the geometrical details, i.c., roughness, of the intercrystalline pore surface on diffusion.
To resolve this apparent disagreement, we recently performed dynamic Monte-Carlo simulations of Knudsen diffusion in two- and three-dimensional fractally rough pores . Jun 01, · Gas and solute diffusion coefficients in pore networks and its description by a simple capillary model.
Authors; show that the diffusion coefficients increase both with increasing coordination number and decreasing coefficient of variation of the pore-size distribution. diffusional conductance of a single pore (D(r)r 2) [l 4 /t] runrevlive.com by: Sep 07, · Measured values are compared with theoretical estimates and are consistent with low bed tortuosities (below 3) expected for media with open porosity above The impact of uncertainties in effective diffusion coefficients on corrections of measured uptake coefficients is runrevlive.com by: 3.
need to establish relationships of packed bed porosity with tortuosity and permeability or diffusivity. The tortuosity depends on porosity T (ε)  and often the correct presentation of T as the function of ε. For granular mixed beds and binary mixtures, in particular both T and ε are related to the volume.
A Review of Porosity and Diffusion in Bentonite. 1 neutral molecules is affected in different ways since the diffusional properties vary. Dif-fusive fluxes are proportional with accessible porosity, chemical potential gradient, and Laboratory experiments have shown that.
The effects of key parameters such as Knudsen number and porosity on the flow structures and permeability are investigated. At last, the relationship between the permeability with Knudsen number and porosity in the slip and transition flow regimes is investigated and expressed with a high coefficient of determination.
Cited by: 2. Jul 13, · This report discusses the use of the discrete element method (DEM) to the porosity distribution of spherical particles in narrow pipes as a function of the pipe-to-particle diameter ratio.
It was found that the packing structure depends mainly on the pipe-to-particle ratio and the particle runrevlive.com by: Analysis of diffusional effects in porous supports. So far, only external diffusional control of immobilised enzyme catalysed reactions has been described.
This has been more due to the ease of the analysis rather than the scale of its application. Tortuosity variation in a low density binary particulate bed Article in Separation and Purification Technology 51(2) · September with 99 Reads How we measure 'reads'.
Knudsen diffusion, gas permeability, and water content in an unconsolidated porous medium Stefan A. Reinecke and Brent E.
Sleep Department of Civil Engineering, University of Cited by: propagation for reservoir characterization James G Berryman Double porosity modeling in elastic wave propagation for reservoir characterization and the coefficients in these linear equations identified The generalization from a single porosity model increases the number of independent coefficients from three to six for an isotropic.
Temperature Dependence of the Elastic Constants of Thoria Specimens of Varying Porosity S. Spinner[ L. Stone[ and F.
Knudsen (January 17, ) L:rh~ runrevlive.com dependence of Young's and the shear modulus of 18 thoria specimens of porOSltlCS rangmg from to percent have been measured by the dynamic resonance method.
Dec 07, · The results suggest that Knudsen diffusion has significant implications for the prediction of organic vapor transport in partially saturated silts and in less permeable soils. An expression was developed for the influence of water saturation on Knudsen diffusion coefficients, using the Brooks-Corey capillary pressure saturation relationship.
weathering, producing secondary or fracture porosity. In a hydrologic sense we have two types of porosity—effective or open porosity that permits fl ow of fl uids or volatiles and ineffective or closed porosity that does not. As our ability to quantify the nature of porosity in complex.The generalization from the single‐porosity case increases the number of independent coefficients for volume deformation from three to six for an isotropic applied stress.
The physical interpretations are based upon considerations of different temporal and spatial runrevlive.com by: Sep 20, · The elastic coefficients of double-porosity models for fluid transport in jointed rock.
Authors. James G. Berryman, All six coefficients are determined from the three poroelastic matrix coefficients and the fracture compressibility from the single assumption that the solid grain modulus of the composite is approximately the same as that of.