Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 561706
Title Multicomponent gas diffusion in nonuniform tubes
Author(s) Veltzke, Thomas; Kiewidt, Lars; Thöming, Jorg
Source AIChE Journal 61 (2015)4. - ISSN 0001-1541 - p. 1404 - 1412.
Publication type Refereed Article in a scientific journal
Publication year 2015
Keyword(s) Analytical transport model - Classical Maxwell-Stefan equations - Experiments on conical tubes - Gas multicomponent diffusion - Two-bulb diffusion experiment

In many technical processes gas, multicomponent diffusion takes place in confinements that are rarely uniform in direction of their long axis (e.g., catalysts pores). Here, we show that in conical tubes multicomponent diffusion is hindered. This effect increases with ratio of inlet to outlet cone radius Λ, indifferent of the orientation of the tube. Based on the Maxwell-Stefan equations, predictive analytical solution for ideal multicomponent diffusion in slightly tapered ducts is developed. In two-bulb diffusion experiments on a uniform tube, the results of Duncan and Toor (1962) were reproduced. Comparison of model and experiment shows that the solution presented here provides a reliable quantitative prediction of the temporal change of H2, N2, and CO2-concentration for both tube geometries, uniform and slightly conical. In the demonstrated case (Λ=3.16), mass diffusion is 68% delayed. Thus, for gaseous diffusion in "real," typically tapered pores the transport limitation is more serious than considered so far.

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