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Consequence of flow nonuniformity on the measurement of effective diffusivity
Author(s) -
Cui L. C.,
Schweich D.,
Villermaux J.
Publication year - 1990
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690360111
Subject(s) - van deemter equation , thermal diffusivity , porosity , dispersion (optics) , mass transfer , diffusion , flow (mathematics) , distribution (mathematics) , mechanics , chemistry , column (typography) , chromatography , thermodynamics , volumetric flow rate , mathematics , physics , geometry , mathematical analysis , optics , organic chemistry , connection (principal bundle)
Measurements of effective diffusivity by the chromatographic method are shown to be biased by nonuniformity of the external porosity in a cross‐section of the column. A very simple model is proposed to interpret experimental results. A modified Van Deemter method is given to extract the axial dispersion and effective diffusion coefficients from chromatographic peaks. This method allows one to ignore the external porosity distribution. Experiments show that even though axial dispersion obeys classical correlations, the internal mass transfer parameters may be strongly affected by the external porosity distribution.