Measuring gas diffusion coefficients by means of a capillary open at one end

1994 ◽  
Vol 37 (5) ◽  
pp. 581-584 ◽  
Author(s):  
N. D. Kosov ◽  
I. V. Poyarkov
Keyword(s):  
Diffusion Coefficients ◽  
Gas Diffusion

Determination of gas diffusion coefficients in saturated porous media: He and CH4 diffusion in Boom Clay

2013 ◽  
Vol 83-84 ◽  
pp. 217-223 ◽  
Author(s):  
Elke Jacops ◽  
Geert Volckaert ◽  
Norbert Maes ◽  
Eef Weetjens ◽  
Joan Govaerts
Keyword(s):  
Porous Media ◽  
Diffusion Coefficients ◽  
Gas Diffusion ◽  
Saturated Porous Media ◽  
Boom Clay

Determination of precise and reliable gas diffusion coefficients by gas chromatography

1976 ◽  
Vol 98 (17) ◽  
pp. 5101-5107 ◽  
Author(s):  
Frank Yang ◽  
Stephen Hawkes ◽  
F. T. Lindstrom
Keyword(s):  
Gas Chromatography ◽  
Diffusion Coefficients ◽  
Gas Diffusion

scholarly journals Highly Permeable Matrimid®/PIM-EA(H2)-TB Blend Membrane for Gas Separation

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 46 ◽  
Author(s):  
Elisa Esposito ◽  
Irene Mazzei ◽  
Marcello Monteleone ◽  
Alessio Fuoco ◽  
Mariolino Carta ◽  
...  
Keyword(s):  
Diffusion Coefficients ◽  
Gas Transport ◽  
Gas Permeability ◽  
Time Lag ◽  
Gas Diffusion ◽  
Gas Permeation ◽  
Spectrometric Analysis ◽  
Competitive Sorption ◽  
Transport Parameters ◽  
Mixed Gas

The effect on the gas transport properties of Matrimid®5218 of blending with the polymer of intrinsic microporosity PIM-EA(H2)-TB was studied by pure and mixed gas permeation measurements. Membranes of the two neat polymers and their 50/50 wt % blend were prepared by solution casting from a dilute solution in dichloromethane. The pure gas permeability and diffusion coefficients of H2, He, O2, N2, CO2 and CH4 were determined by the time lag method in a traditional fixed volume gas permeation setup. Mixed gas permeability measurements with a 35/65 vol % CO2/CH4 mixture and a 15/85 vol % CO2/N2 mixture were performed on a novel variable volume setup with on-line mass spectrometric analysis of the permeate composition, with the unique feature that it is also able to determine the mixed gas diffusion coefficients. It was found that the permeability of Matrimid increased approximately 20-fold with the addition of 50 wt % PIM-EA(H2)-TB. Mixed gas permeation measurements showed a slightly stronger pressure dependence for selectivity of separation of the CO2/CH4 mixture as compared to the CO2/N2 mixture, particularly for both the blended membrane and the pure PIM. The mixed gas selectivity was slightly higher than for pure gases, and although N2 and CH4 diffusion coefficients strongly increase in the presence of CO2, their solubility is dramatically reduced as a result of competitive sorption. A full analysis is provided of the difference between the pure and mixed gas transport parameters of PIM-EA(H2)-TB, Matrimid®5218 and their 50:50 wt % blend, including unique mixed gas diffusion coefficients.

A Power-Law Mixing Rule for Predicting Apparent Diffusion Coefficients of Binary Gas Mixtures in Heavy Oil

2017 ◽  
Vol 140 (5) ◽  
Author(s):  
Hyun Woong Jang ◽  
Daoyong Yang ◽  
Huazhou Li
Keyword(s):  
Diffusion Coefficient ◽  
Apparent Diffusion Coefficient ◽  
Heavy Oil ◽  
Diffusion Coefficients ◽  
Gas Mixtures ◽  
Gas Diffusion ◽  
Gas Mixture ◽  
Mixing Rule ◽  
Heavy Oils ◽  
Apparent Diffusion

A power-law mixing rule has been developed to determine apparent diffusion coefficient of a binary gas mixture on the basis of molecular diffusion coefficients for pure gases in heavy oil. Diffusion coefficient of a pure gas under different pressures and different temperatures is predicted on the basis of the Hayduk and Cheng's equation incorporating the principle of corresponding states for one-dimensional gas diffusion in heavy oil such as the diffusion in a pressure–volume–temperature (PVT) cell. Meanwhile, a specific surface area term is added to the generated equation for three-dimensional gas diffusion in heavy oil such as the diffusion in a pendant drop. In this study, the newly developed correlations are used to reproduce the measured diffusion coefficients for pure gases diffusing in three different heavy oils, i.e., two Lloydminster heavy oils and a Cactus Lake heavy oil. Then, such predicted pure gas diffusion coefficients are adjusted based on reduced pressure, reduced temperature, and equilibrium ratio to determine apparent diffusion coefficient for a gas mixture in heavy oil, where the equilibrium ratios for hydrocarbon gases and CO2 are determined by using the equilibrium ratio charts and Standing's equations, respectively. It has been found for various gas mixtures in two different Lloydminster heavy oils that the newly developed empirical mixing rule is able to reproduce the apparent diffusion coefficient for binary gas mixtures in heavy oil with a good accuracy. For the pure gas diffusion in heavy oil, the absolute average relative deviations (AARDs) for diffusion systems with two different Lloydminster heavy oils and a Cactus Lake heavy oil are calculated to be 2.54%, 14.79%, and 6.36%, respectively. Meanwhile, for the binary gas mixture diffusion in heavy oil, the AARDs for diffusion systems with two different Lloydminster heavy oils are found to be 3.56% and 6.86%, respectively.

A field method for measurement of gas diffusion into soils

Soil Research ◽  
1964 ◽  
Vol 2 (2) ◽  
pp. 133 ◽  
Author(s):  
DS McIntyre ◽  
JR Philip
Keyword(s):  
Theoretical Analysis ◽  
Experimental Method ◽  
Diffusion Coefficients ◽  
Field Measurement ◽  
Field Method ◽  
Gas Diffusion ◽  
Relative Importance ◽  
Transient Method ◽  
Apparatus Design ◽  
Laboratory Conditions

A transient method for field measurement of gas diffusion into soil is presented. The theory of the method and the results of preliminary tests are given. Diffusion takes place from a reservoir mounted on a tube driven into the soil. The theoretical analysis is used in the design of the experimental method, the relative importance of the various parameters involved in apparatus design and in measurement being evaluated. The apparatus is described and sample calculations of parameters given. When porosity is uniform with depth, diffusion coefficients obtained in the field agree well with results of diffusion measurements of other workers made under better controlled (laboratory) conditions.

Dense Gas Diffusion Coefficients for the Methane-Propane System

1969 ◽  
Vol 8 (4) ◽  
pp. 779-786 ◽  
Author(s):  
D. E. Woessner ◽  
B. S. Snowden ◽  
R. A. George ◽  
J. C. Melrose
Keyword(s):  
Diffusion Coefficients ◽  
Gas Diffusion ◽  
Dense Gas
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