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          Institute: MPI für Dynamik komplexer technischer Systeme     Collection: Physical and Chemical Foundations of Process Engineering     Display Documents

ID: 572130.1, MPI für Dynamik komplexer technischer Systeme / Physical and Chemical Foundations of Process Engineering
From random sphere packings to regular pillar arrays: Effect of the macroscopic confinement on hydrodynamic dispersion
Authors:Daneyko, A.; Khirevich, S.; Hoeltzel, A.; Seidel-Morgenstern, A.; Tallarek, U.
Date of Publication (YYYY-MM-DD):2011
Title of Journal:Journal of Chromatography A
Issue / Number:45
Start Page:8231
End Page:8248
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:Flow and mass transport in bulk and confined chromatographic supports comprising random packings of solid, spherical particles and hexagonal arrays of solid cylinders (regular pillar arrays) are studied over a wide flow velocity range by a numerical analysis scheme, which includes packing generation by a modified Jodrey-Tory algorithm, three-dimensional flow field calculations by the lattice-Boltzmann method, and modeling of advective-diffusive mass transport by a random-walk particle-tracking technique. We demonstrate the impact of the confinement and its cross-sectional geometry (circular, quadratic, semicircular) on transient and asymptotic transverse and longitudinal dispersion in random sphere packings, and also address the influence of protocol-dependent packing disorder and the particle-aspect ratio. Plate height curves are analyzed with the Giddings equation to quantify the transcolumn contribution to eddy dispersion. Confined packings are compared with confined arrays under the condition of identical bed porosity, conduit cross-sectional area, and laterally fully equilibrated geometrical wall and corner effects on dispersion. Fluid dispersion in a regular pillar array is stronger affected by the macroscopic confinement and does not resemble eddy dispersion in random sphere packings, because the regular microstructure cannot function as a mechanical mixer like the random morphology. Giddings’ coupling theory fails to preserve the nature of transverse dispersion behind the arrays’ plate height curves, which approach a linear velocity-dependence as transverse dispersion becomes velocity-independent. Upon confinement this pseudo-diffusive behavior can outweigh the performance advantage of the regular over the random morphology.

Copyright © 2011 Published by Elsevier B.V. [accessed Nobember 16th 2011]
Free Keywords:Ordered pillar arrays; Random sphere packings; Packing disorder; Wall effects; Eddy dispersion; High-performance computing
External Publication Status:published
Document Type:Article
Communicated by:Andreas Seidel-Morgenstern
Affiliations:MPI für Dynamik komplexer technischer Systeme/Physical and Chemical Foundations of Process Engineering
External Affiliations:Philipps-Universität Marburg,
Department of Chemistry,
35032 Marburg, Germany

Otto-von-Guericke-Universität Magdeburg,
Universitätsplatz 2, 39106 Magdeburg, Germany
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