On the Determination of High-pressure Mass-diffusion Coefficients for Binary Mixtures

2003 ◽  
Author(s):  
Kenneth Harstad ◽  
Josette Bellan
Keyword(s):  
High Pressure ◽  
Binary Mixtures ◽  
Diffusion Coefficients ◽  
Mass Diffusion

Apparatus for the Determination of Diffusion Coefficients in Fused Salts (NaNO3) at High Pressure

1964 ◽  
Vol 35 (7) ◽  
pp. 807-810 ◽  
Author(s):  
S. B. Tricklebank ◽  
L. Nanis ◽  
J. O'M. Bockris
Keyword(s):  
High Pressure ◽  
Diffusion Coefficients ◽  
Fused Salts

Determination of Diffusion Coefficient of Carbon Dioxide in Polyethylene by the Method of Moments

1993 ◽  
Vol 58 (2) ◽  
pp. 252-258 ◽  
Author(s):  
Jan Jirásek ◽  
Milan Šípek
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
Diffusion Coefficient ◽  
Method Of Moments ◽  
Diffusion Coefficients ◽  
Optimization Method ◽  
Diffusion Equations ◽  
High Pressure Polyethylene ◽  
Good Agreement

By using the method of moments, the values of diffusion coefficients of carbon dioxide in high-pressure polyethylene of two different thicknesses were determined at 25 °C. The values of diffusion coefficients determined with the accuracy of about ±3% are in good agreement both with the values obtained by the optimization method, and with the published values determined on the basis of asymptotic solutions of diffusion equations.

An Investigation of Concentration Dependency of Mass Diffusion Coefficients in Multi-Component Diffusion

2010 ◽  
Author(s):  
Atsuki Komiya ◽  
Juan F. Torres ◽  
Junnosuke Okajima ◽  
Shuichi Moriya ◽  
Shigenao Maruyama ◽  
...  
Keyword(s):  
Experimental Data ◽  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Superposition Principle ◽  
Mass Diffusion ◽  
Diffusion Field ◽  
Transient Diffusion ◽  
Concentration Dependency ◽  
The Difference

In this paper the concentration dependency of mass diffusion coefficients in binary system was investigated. We have developed a novel and accurate visualization system using a small area of transient diffusion fields by adopting a phase shifting technique. Through accurate visualization of the transient diffusion field, it is possible to determine the mass diffusion coefficient. Unlike a conventional interferometer, the proposed system provides high spatial resolution profiles of concentration even though the target area is less than 1.0 mm. This allows the measurement of local transient diffusion field with a high accuracy. The determination of mass diffusion coefficient of each component in multi-component system was also conducted. For the accurate and reliable measurement of mass diffusion coefficient, the experimental error should be taken into account. The experimental data usually contains unexpected accidental error and inherent errors of the measurement system. In this study, an optimization technique using conjugate gradient method is developed for the precise determination of the mass diffusion coefficients. The difference between the experimental and numerical concentration distribution is set as the objective function for the optimization method. The conjugate gradient method searches the optimal value by minimizing the objective function. For the concentration dependency evaluation, sodium chloride (NaCl) in pure water was selected as solute. For determination of each mass diffusion coefficient in multi-component system, NaCl and lysozyme in buffer solution was selected. The experiments were performed under isothermal conditions. The proposed measurement method was validated by comparing the measured data with those available in the literature. The results indicated that the concentration dependency was successfully investigated from the experimental data. The mass diffusion coefficient of each component also could be determined from the experimental data as evidenced by good agreement with the published data. The difference between the reference and determined value of mass diffusion coefficient was less than 10%. It can be said that the diffusion of each solute inside the cell progresses independently within the dilute concentration ranges and the superposition principle of concentration of NaCl and lysozyme was satisfied. The influence of concentration of solution on the diffusion process and allowable concentration range of the superposition principle are determined and discussed.

Determination of Methane Diffusion Coefficients in Live Oils for Tight Reservoirs at High Pressures

2021 ◽  
Author(s):  
Yibo Yang ◽  
Teresa Regueira ◽  
Hilario Martin Rodriguez ◽  
Alexander Shapiro ◽  
Erling Halfdan Stenby ◽  
...  
Keyword(s):  
High Pressure ◽  
Diffusion Coefficients ◽  
High Pressures ◽  
Diffusion Method ◽  
Pressure Diffusion ◽  
Reservoir Conditions ◽  
Tight Reservoirs ◽  
Methane Diffusion ◽  
Live Oil

Abstract Molecular diffusion plays a critical role in gas injection in tight reservoirs such as liquid-rich shale. Despite recent efforts on measuring diffusion coefficients at high pressures, there is a general lack of the diffusion coefficients in live oil systems at reservoir conditions relevant to the development of these tight reservoirs. The reported diffusion coefficients often differ in orders of magnitude, and there is no consensus on the reliability of the common correlations for liquid phase diffusion coefficients, such as the extended Sigmund correlation. We employed the constant volume diffusion method to measure the high-pressure diffusion coefficients in a newly designed high-pressure tube. The experimental method was first validated using methane + hexadecane and methane + decane, and then used to measure the methane diffusion coefficients in two live oils at reservoir conditions. The obtained data were processed by compositional simulation to determine the diffusion coefficients. The diffusion coefficients measured for methane + hexadecane and methane + decane are in agreement with the existing literature data. For methane + live oil systems, however, the diffusion coefficients estimated by the extended Sigmund correlation are much lower than the measured results. An over ten times adjustment is needed to best fit the pressure decay curves. A further check reveals that for live oil systems, the reduced densities are often in the extrapolated region of the original Sigmund model. The curve in this region of the extended Sigmund correlation has a weak experimental basis, which may be the reason for its large deviation. The estimates from other correlations like Wilke-Chang and Hayduk-Minhas also give very different results. We compared the diffusion coefficients in high-pressure oils reported in the literature, showing a large variation in the reported values. All these indicate the necessity for further study on accurate determination of high-pressure diffusion coefficients in live oils of relevance to shale and other tight reservoirs.

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