The effect of relative humidity on binary gas diffusion

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Journal titleThe journal of physical chemistry. B
Pages83698374; # of pages: 6
SubjectGas; diffusion cell; Fuller-Schettler-Giddings (FSG); FSG empirical equation
AbstractThe dependence of diffusion coefficient of O2-N2 mixture in the presence of water vapor was experimentally determined as a function of relative humidity (RH) with different temperatures using an in-house made Loschmidt diffusion cell. The experimental results showed that O2-N2 diffusion coefficient increased more than 17% when RH increased from 0% to 80% at 79 °C. In the experiments, the RH in both top and bottom chambers of the diffusion cell were the same, and the pressure inside the diffusion cell was kept as ambient pressure (1 atm.). Maxwell-Stefan theory was employed to analyze the mass transport in the diffusion cell, and found that there was no effective water vapor diffusion taking place, indicating that the gas diffusion in this ternary (O2-N2-water vapor) system could be considered binary gas (O2-N2) diffusion. The Fuller, Schettler, and Giddings (FSG) empirical equation of the kinetic theory of gases was generalized to accommodate the dependence of the binary diffusion coefficient on the RH. The prediction of the generalized equation was found to be consistent with experimental results with the difference of less than 1.5%, showing that the generalized equation could be applied to calculate the diffusion coefficients of the binary gaseous mixture with different temperature and RH values. The effect of water vapor on the increase of O2-N2 diffusion coefficient was discussed using molecule theory.
Publication date
PublisherAmerican Chemical Society
Copyright noticeThe material in this document is covered by the provisions of the Copyright Act, by Canadian laws, policies, regulations and international agreements. Such provisions serve to identify the information source and, in specific instances, to prohibit reproduction of materials without written permission
AffiliationNRC Institute for Fuel Cell Innovation (IFCI-IIPC); National Research Council Canada
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Peer reviewedYes
NPARC number9126873
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Record identifierc82cc270-0694-46d0-9815-705a373864f0
Record created2009-10-02
Record modified2017-03-23
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