Results 171 to 180 of about 3,974 (207)
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KNUDSEN DIFFUSION IN POROUS CATALYSTS WITH A FRACTAL INTERNAL SURFACE
Fractals, 1995Porous amorphous catalysts often have a fractal internal surface down to molecular scales. The movement of gas molecules inside the narrow channels that constitute all or most of the pore space, is mainly hindered by collisions with the surface, rather than with each other: Knudsen diffusion, rather than bulk molecular diffusion is then the main ...
Coppens, Marc-Olivier +1 more
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Physical Review E, 2005
We study molecular diffusion in nanopores with different types of roughness under the exclusion of mutual molecular collisions, i.e., in the so-called Knudsen regime. We show that the diffusion problem can be mapped onto Levy walks and discuss the roughness dependence of the diffusion coefficients D(s) and D(t) of self- and transport diffusion ...
Stefanie, Russ +3 more
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We study molecular diffusion in nanopores with different types of roughness under the exclusion of mutual molecular collisions, i.e., in the so-called Knudsen regime. We show that the diffusion problem can be mapped onto Levy walks and discuss the roughness dependence of the diffusion coefficients D(s) and D(t) of self- and transport diffusion ...
Stefanie, Russ +3 more
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Knudsen Diffusivity of a Hard Sphere in a Rough Slit Pore
Physical Review Letters, 2003An analytic theory for the Knudsen self-diffusivity D(s) of hard spheres in an atomically rough slit-shaped pore is presented which quantitatively matches simulation results. The theory assumes that, due to chaotic molecular trajectories caused by surface morphology, collisions of gas molecules with the wall are partly diffuse and partly specular, the ...
Gaurav, Arya +2 more
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Simulations of Nanoscale Gas Flow with Knudsen Diffusion and Slip Flow
Mathematical Models and Computer Simulations, 2021Summary: The traditional oil and gas reservoirs used for hydrocarbon production have been partially exhausted and the global energy market is looking for new unconventional energy sources. According to some estimates, shale gas resources in the world amount to 200 trillion \(m^3\), but only a small part is recoverable from the point of view of modern ...
Nesterova, I. S., Gerke, K. M.
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Industrial & Engineering Chemistry Fundamentals, 1973
Abstract Diffusion of a ternary gas mixture in the transition region of diffusion was experimentally investigated in an isobaric open system of fine glass capillaries in parallel. The flux data for HeNeAr were obtained over a 673/1 pressure range from 0·450 to 303·2 mm Hg abs.
Ronald R. Remick, Christie J. Geankoplis
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Abstract Diffusion of a ternary gas mixture in the transition region of diffusion was experimentally investigated in an isobaric open system of fine glass capillaries in parallel. The flux data for HeNeAr were obtained over a 673/1 pressure range from 0·450 to 303·2 mm Hg abs.
Ronald R. Remick, Christie J. Geankoplis
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Knudsen diffusion through thin porous films
The Journal of Chemical Physics, 1988Upper and lower bounds on Knudsen flow rates through a random porous film of finite thickness are applied to a bed of randomly overlapping spheres. This extension of Clausing’s original work on short tubes, to random porous media, yields estimates of the Knudsen flow as a function of film thickness.
Timothy L. Faley, William Strieder
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Anomalous diffusion limit for the Knudsen gas
Asymptotic Analysis, 1998The author presents a short and self-contained proof of the results of \textit{Ch. Börgers}, \textit{C. Greengard} and \textit{E. Thomann} [SIAM J. Appl. Math. 52, No. 4, 1057-1075 (1992; Zbl 0761.76089)] concerning the diffusion limit of free-molecular flows in thin plane channels without using any limit theorem from probability theory.
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From Knudsen diffusion to Levy walks
Europhysics Letters (EPL), 1997In this letter, we show that 3D Knudsen diffusion inside disordered porous media can be analysed in terms of a continuous time random walk formalism (CTRW) recently proposed for 1D intermittent chaotic systems. This approach mainly involves the pore chord distribution function fp(r).
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Knudsen diffusion in bidisperse mixtures of uniform spheres
Industrial & Engineering Chemistry Research, 1987Donnees sur la diffusion de Knudsen, d'un gaz non adsorbant, dans un modele de milieu poreux, non consolide.
Tremitchell Wright +2 more
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Surface Diffusion Parallel with Knudsen Flow
Separation Science, 1976Abstract A phenomenological theory is derived for surface diffusion of noncondensible gases (also in the absence of capillary condensation) parallel with Knudsen flow. This theory does not require any specific model for adsorption and diffusion. The only assumption needed is the local equilibrium condition between gas phase and adsorbed phase along the
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