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A Closed Tube Method for Measuring Gas Diffusion Coefficients
Author(s) -
Tokunaga T. K.,
Waldron L. J.,
Nemson J.
Publication year - 1988
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1988.03615995005200010003x
Subject(s) - dimensionless quantity , thermal diffusivity , diffusion , volume (thermodynamics) , thermodynamics , tube (container) , logarithm , gaseous diffusion , range (aeronautics) , mechanics , analytical chemistry (journal) , chemistry , materials science , porous medium , porosity , chromatography , mathematics , physics , mathematical analysis , composite material , electrode
A transient, closed tube method for measuring both ordinary gas diffusivities and porous media effective diffusivities is presented. The current method is suitable for measuring gas diffusivities in air‐dry systems over a range of temperatures. Gas concentrations are continuously monitored in a well‐stirred volume of a single end chamber, which is connected to a closed sample chamber during experiments. An analytic solution for this diffusion process is available in which, after a sufficient time, the diffusivity of the sample is obtained from the slope of the logarithm of dimensionless concentration excess versus time. The method was checked by comparing measurements of N 2 ‐O 2 gas diffusivities at 0, 30, and 60 °C to various previously reported values in the literature. The measured diffusivities fall within the uncertainties of these earlier works.