Isotropy of sphere packings in a cylindrical confinement

Agrawal, Nikhil; Nair, P.M.; Pöschel, Thorsten; Roy, Shantanu

doi:10.1016/j.cej.2018.08.206

Cited by 11 publications

(2 citation statements)

References 30 publications

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“…Correlations of void fraction are needed for various packing states and different particle shapes. Agrawal et al (92) have used computer generation of sphere packs to investigate whether packing defects observed at the top of the bed propagate through the bed, causing local flow variations. They suggested that measures of packing nonisotropy should be considered, in addition to measures of void fraction.…”

Section: Fixed Bed Structure and Hydrodynamicsmentioning

confidence: 99%

Computational Fluid Dynamics for Fixed Bed Reactor Design

Dixon

Partopour

2020

Annu. Rev. Chem. Biomol. Eng.

125

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Flow, heat, and mass transfer in fixed beds of catalyst particles are complex phenomena and, when combined with catalytic reactions, are multiscale in both time and space; therefore, advanced computational techniques are being applied to fixed bed modeling to an ever-greater extent. The fast-growing literature on the use of computational fluid dynamics (CFD) in fixed bed design reflects the rapid development of this subfield of reactor modeling. We identify recent trends and research directions in which successful methodology has been established, for example, in computer generation of packings of complex particles, and where more work is needed, for example, in the meshing of nonsphere packings and the simulation of industrial-size packed tubes. Development of fixed bed reactor models, by either using CFD directly or obtaining insight, closures, and parameters for engineering models from simulations, will increase confidence in using these methods for design along with, or instead of, expensive pilot-scale experiments.

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Section: Fixed Bed Structure and Hydrodynamicsmentioning

confidence: 99%

Computational Fluid Dynamics for Fixed Bed Reactor Design

Dixon

Partopour

2020

Annu. Rev. Chem. Biomol. Eng.

125

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“…These methods have allowed relatively rapid production of a large number of packed tubes at very fine increments of N, which has led to a detailed examination of the void fraction ε and the pressure drop ΔP/L. Packing defects that may lead to the formation of local hot spots have been analyzed, 13 while the importance of the relationship between fluid flow and the structural properties of the bed has been emphasized 14 for the description of flow through the interstitial spaces.…”

Section: Local Fixed-bed Structurementioning

confidence: 99%

Local Structure Effects on Heat Transfer in Very Low Tube-to-Particle Diameter Ratio Fixed Beds of Spheres

Dixon

2021

Ind. Eng. Chem. Res.

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New fixed-bed radial heat transfer experimental data are reported for beds of perfect spheres for tube-to-particle diameter ratio (N) in the range of 1.38–6.29. These results are combined with a re-analyzed smaller data set for spheres in the range 1.13 ≤ N ≤ 6.4 from an earlier publication. Very strong local bed structure effects were found for the estimates of effective radial thermal conductivity and apparent wall heat transfer coefficient, giving maximum and minimum values at particular N, which departed from the overall trend. The extreme values often corresponded with fluctuations of the void fraction ε, but they could not be explained by the bulk void fraction alone. Local bed structures resulted in changes in the flow pattern. Standard correlations can predict only average changes and trends, due to their neglect of local structure, and may be considerably in error for any particular N.

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