Calculation of diffusion coefficients at any temperature and pressure from a single measurement. II. Heterodiffusion

1981 ◽  
Vol 24 (6) ◽  
pp. 3606-3609 ◽  
Author(s):  
K. Alexopoulos ◽  
P. Varotsos
Keyword(s):  
Diffusion Coefficients ◽  
Single Measurement ◽  
Temperature And Pressure

scholarly journals Compilation and evaluation of gas phase diffusion coefficients of halogenated organic compounds

2018 ◽  
Vol 5 (7) ◽  
pp. 171936 ◽  
Author(s):  
Wenjun Gu ◽  
Peng Cheng ◽  
Mingjin Tang
Keyword(s):  
Gas Phase ◽  
Diffusion Coefficients ◽  
Input Parameter ◽  
Empirical Method ◽  
Trace Gas ◽  
Temperature And Pressure ◽  
Organic Halogens ◽  
Semi Empirical ◽  
Method Show ◽  
Good Agreement

Organic halogens are of great environmental and climatic concern. In this work, we have compiled their gas phase diffusivities (pressure-normalized diffusion coefficients) in a variety of bath gases experimentally measured by previous studies. It is found that diffusivities estimated using Fuller's semi-empirical method agree very well with measured values for organic halogens. In addition, we find that at a given temperature and pressure, different molecules exhibit very similar mean free paths in the same bath gas, and then propose a method to estimate mean free paths in different bath gases. For example, the pressure-normalized mean free paths are estimated to be 90, 350, 90, 80, 120 nm atm in air (and N 2 /O 2 ), He, argon, CO 2 and CH 4 , respectively, with estimated errors of around ±25%. A generic method, which requires less input parameter than Fuller's method, is proposed to calculate gas phase diffusivities. We find that gas phase diffusivities in He (and air as well) calculated using our method show fairly good agreement with those measured experimentally and estimated using Fuller's method. Our method is particularly useful for the estimation of gas phase diffusivities when the trace gas contains atoms whose diffusion volumes are not known.

Molecular dynamics simulation of multi-constituent gas diffusion properties in Venus atmosphere

2021 ◽  
Author(s):  
Wen Gao ◽  
Xiaoning Yang ◽  
Jing Wang ◽  
Quanwen Hou ◽  
Yanqiang Bi ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficients ◽  
Gas Diffusion ◽  
Dynamics Simulation ◽  
Diffusion Characteristics ◽  
Temperature And Pressure ◽  
Experimental Values ◽  
Dynamics Simulations ◽  
Interdiffusion Coefficients ◽  
Diffusion Properties

Abstract The purpose of studying the Venus’s atmosphere is to model and simulate Venus’s environment. One of the key parameters of the Venus’s atmosphere is diffusion coefficient. Experimental measurements of diffusion coefficients are particularly difficult under Venus’s environmental conditions. Molecular dynamics have become an important method for studying the properties and dynamics of microscopic systems. In this paper, the equilibrium molecular dynamics (EMD) simulations are used to calculate the interdiffusion coefficients of carbon dioxide (CO2) and nitrogen (N2) at room temperature and pressure in combination with Darken's equation. And the results are compared with experimental values and empirical equations to verify the rationality of the calculation method and the accuracy of the results. The interdiffusion coefficients of trace gases on the surface of Venus for the CO2 system in different states and the CO2-N2 interdiffusion coefficients with altitude in the Venus environment are given. The results show that the diffusion coefficients of the gases on the surface of Venus are two orders of magnitude smaller than those in the Earth's atmosphere and molecular dynamics simulations can well predict the diffusion characteristics of the Venus’s atmosphere and support the simulation of the Venus’s surface environment and the Venus’s atmosphere model.

Methodologies for the rapid determination of the diffusion interaction parameter using Taylor dispersion analysis

2016 ◽  
Vol 8 (2) ◽  
pp. 386-392 ◽  
Author(s):  
Seyi Latunde-Dada ◽  
Rachel Bott ◽  
David Barker ◽  
Oksana Iryna Leszczyszyn
Keyword(s):  
Interaction Parameter ◽  
Diffusion Coefficients ◽  
Rapid Determination ◽  
Taylor Dispersion ◽  
Dispersion Analysis ◽  
Single Measurement ◽  
Diffusion Interaction

Using Taylor dispersion analysis to determine diffusion coefficients as a function of concentration in a single measurement.

scholarly journals Diffusion in periclase by combination of analytical formulas and thermodynamic model

2012 ◽  
Vol 12 (6) ◽  
pp. 1841-1844
Author(s):  
E. Dologlou
Keyword(s):  
Thermodynamic Model ◽  
Diffusion Coefficients ◽  
The Self ◽  
Single Measurement ◽  
Bulk Properties ◽  
Self Diffusion ◽  
Earth’S Mantle ◽  
Analytical Formulas ◽  
Range Of Values ◽  
Slight Discrepancy

Abstract. Analytical formulas for the temperature dependence of elastic constants of MgO combined with a thermodynamic model, which interconnects bulk properties to point defect parameters, can successfully reproduce the self diffusion coefficients of periclase at temperatures representative of the Earth's mantle conditions. Although the calculated diffusion coefficients are estimated from a single measurement and cover a broad range of values (i.e. five orders of magnitude), an almost excellent agreement with the experimental ones is observed. The slight discrepancy at the highest temperature lies at error margins.

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