interdiffusion of gases in a low permeability graphite at

Diffusion of Gases in Silicone Polymers: Molecular

Diffusion coefficients of He, O 2, N 2, CO 2, and CH 4-12 s). The number of jumps and the average length of a jump of a penetrant molecule inside a silicone matrix decrease as the size of the molecule and of the polymer side chain increase. Some problems


Results from these two models are compared to isothermal experimental data for He-Ar gas diffusion in a low-permeability graphite. Air-water vapor comparisons have also been performed, although data more are not available, for the low-permeability graphite system used for the helium-argon data.

Gas Transport in MSRE Moderator Graphite II. Effects of

and very low permeability coefficients were requested. To meet these requirements, it is neces- sary to include additional, special treatments in the graphite fabrication process. These treatments commonly entail impregnation of the graphite with a suitable fluid

Maximizing the right stuff: The trade

During the 1980s, permeability data on six common gases (He, H 2, O 2, N 2, CO 2, and CH 4) were compiled, and the trade-off relationship between permeability and selectivity was analyzed. Polymers having the highest selectivity at a given permeability lay near or on a line, called the upper bound, obeying the following relation ( 21 )


Understanding methane diffusion and adsorption, and gas flow and equilibrium in the low-permeability matrix of shale is crucial for shale formation evaluation and for predicting gas production. Modeling of diffusion in low-permeability shale rocks requires use of the Dusty gas model more


i I I I I I II These data, which are for oxidation in slowly moving air at one atmos- I phere, show (by extrapolation) that platinum, rhodium, palladium, and iridium recess at rates of less than 0. 1 mils/hr at temperatures to 2000 C. recession rates of osmium and

Improvement in physical properties of single

For the single-cell test, the inlet fuel gases of the anode and the cathode were hydrogen and oxygen, respectively. The test was carried out under atmospheric pressure. The relative humidity (RH) values of the inlet gases measured immediately after passing through the external bubble-type humidifier at 50 C were approximately 99.9% and 15% when no humidification was applied.


2012/7/17These atomically thin materials provide low hydraulic conductivity and low Hg-vapor permeability at very low areal density, which is promising for practical, cost effective materials. Nair et al. 15 report essentially no vapor permeability in the dry state, but their films are much thicker (0.1 – 1 μm) and thus their results may be seen as consistent with the present ones for ultrathin 25


gases is a consequence partly of their small molecular size and partly of their low solubility and hence low concentration in the polymer. When two such gases permeate simultaneously at moderate or low pressures neither affects the permeability properties of

Gas Diffusion Layer: Characteristics and Modeling

The GDL is an essential part of the fuel cell because it causes the gases to spread out to maximize the contact surface area with the catalyst layer. The thicknesses of various gas diffusion materials vary between 0.0017 and 0.04 cm with a porosity between 70 .

Gas Transport in MSRE Moderator Graphite. I. Review of Theory

GAS TRANSPORT IN MSRE MODERATOR GRAPHITE.1. REVIEW OF'THEORY AND COUNTERDIFFUSION EXPERIMENTS R. B. Evans III A. P. Malinauskas J. L. Rutherford The authors devel ABSTRACT p equations describing gas transp rt in p I us

The effects of compression and gas diffusion layers on the

1999/11/1The pressure ranges of the Super Low and Low films are 70–350 lb f /in. 2 and 350–1400 lb f /in. 2, respectively. A swatch of film was prepared with dimensions of 0.05 m by 0.05 m and it was inserted between the MEA and the diffusion layer as shown in Fig. 1 .

Tritium Barriers and Tritium Diffusion in Fusion Reactors

2 4.116.1. INTRODUCTION As fusion energy research progresses over the next several decades, and ignition and energy production are attempted, the fuel for fusion reactors will be a combination of deuterium and tritium. From a safety point of view, these are not


GASEOUS DIFFUSION AND PORE STRUCTURE IN NUCLEAR GRAPHITES T.J. MAYS, B. McENANEY, B.T. KELLY School of Materials Science, Bath University, XA9642926 Bath, United Kingdom Abstract With the incentive of providing more information for

Improving Investment Casting Mold Permeability Using Graphite

The key reason for low permeability is the use of fine particle-size material with high packing density. While the dense structure gives high strength at low thicknesses, it also restricts the flow of gases. In industry, the issue of low permeability of investment

Interdiffusion of Gases in a Low Permeability Graphite at

An experimental investigation of the interdiffusion behavior of gases in a low permeability graphite was performed by sweeping the opposite faces of a graphite septum with helium and argon at uniform pressure and measuring the diffusive flux of both gases. The

On the law of the diffusion of gases

1995/3/31The experiments on the permeability of the stucco by gases under pres- sure, above detailed, were projected with a view to settle this point among others; and they are evidently incompatible with such an application of the theory, for hydrogen passes 2.4 times

Pore Connectivity, Episodic Flow, and Unsaturated Diffusion in

Pore Connectivity, Episodic Flow, and Unsaturated Diffusion in Fractured Tuff Qinhong Hu 1, Robert P. Ewing 2, Liviu Tomutsa 3, and Michael J. Singleton 1 1 Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, United States,


Graphite Used in Specialty Markets G-series grades of graphite are specialty materials, purified, and enhanced to reduce permeability / increase density. They are non-treated, fine grain materials with ash levels below 50 ppm. The G-series materials also have a

Diffusion theory for transport in porous media: Transition

WATER RESOURCES RESEARCH, VOL. 34, NO. 7, PAGES 1685-1693, JULY 1998 Diffusion theory for transport in porous media: Transition- probability densities of diffusion processes corresponding to advection-dispersion equations Eric M. LaBolle


Interdiffusion of Gases in a Low Permeability Graphite at Uniform Pressure Journal Article Evans, R. B. ; Watson, G. M. ; Truitt, J. - Journal of Applied Physics An experimental investigation of the interdiffusion behavior of gases in a low-permeability graphite was performed by sweeping the opposite faces of a graphite septum with helium and argon at uniform pressure and measuring the

A technical review on gas diffusion, mechanism and

2014/11/30At low humidity, the performance was the best where the GDL had the smallest MPL pore size and lowest through-plane permeability because the MPL prevented MEA dehydration. At high humidity, the pre-eminent performance was found using GDLs with a mean MPL pore diameter of 3 mm and had an intermediate through-plane permeability value as it was also reported in [ 106 ].

Title Permeation of Gases in Poly(2

Transport and solution behavior of a series of inert gases (helium, argon, nitrogen, krypton, and xenon) in poly(2-vinylpyridine)-block-polyisoprene was studied by transient permeability measurements at temperatures from 25 to 60 C. Temperature dependence of

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