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Dispersion models of unsteady tubular reactors
Author(s) -
Subramanian R. Shankar,
Gill William N.,
Marra Richard A.
Publication year - 1974
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450520504
Subject(s) - dispersion (optics) , laminar flow , mechanics , inlet , constant (computer programming) , thermodynamics , range (aeronautics) , variable (mathematics) , flow (mathematics) , distribution (mathematics) , volumetric flow rate , mathematics , materials science , chemistry , physics , mathematical analysis , computer science , optics , geology , programming language , geomorphology , composite material
Axial dispersion in time‐variable laminar flow in a tubular reactor is analyzed using an exact procedure for the case of a homogenous first‐order reaction. For the first time since the Taylor Dispersion model was originally introduced for the modeling of reactors, its validity is examined over a wide range of the reaction rate parameter by comparison against an exact analysis. It is shown that a constant coefficient dispersion model can be obtained from first principles for large values of time only for initial distribution problems; however, this simple approximate model also is reasonably good for describing concentration distributions for the present inlet distribution problem for slow reactions and for axial locations sufficiently far away from the inlet. For rapid reactions, while the dispersion model is inaccurate in describing axial concentration distributions, it is surprisingly good for predicting the reactor length required for complete conversion. In contrast to the conclusion of a recent article, it will be shown that the dispersion coefficient is independent of the reaction rate constant.