Abstract
The macro-scale flow behaviour of granular materials in gas fluidization is governed by particle-particle and gas-particle interactions, which are affected significantly by particle size and shape. Understanding the micro-scale flow structure of fine non-spherical particles is essential for process design, optimisation and control. In this work, the combined approach of computational fluid dynamics for gas phase and discrete element method for particles is used to study flow and force structures of fine ellipsoids in gas fluidization. The results reveal that fine particles have vortex flow structure in fluidized beds, and the vortex flow becomes more significant particularly for oblate particles. The microscopic structure analysis demonstrates that when aspect ratio deviates from 1.0, the packed beds could experience compaction, and in expanded beds, the bed expansion ratio increases. The effect of particle size is investigated, showing that with the decrease of particle size, the mean coordination number decreases due to more significant role of van der Waals force. Ellipsoids exhibit higher orientation order which varies greatly with gas velocity and particle size. In fluidized beds, ellipsoids tend to flow in small projected area to the fluid flow direction to reduce the flow resistance. The bed expansion criteria established in the literature are confirmed still valid for ellipsoids, but the gas velocity range for expanded bed interval is much wider than spheres.
| Original language | English |
|---|---|
| Pages (from-to) | 11-26 |
| Number of pages | 16 |
| Journal | Chemical Engineering Science |
| Volume | 163 |
| DOIs | |
| Publication status | Published - 18 May 2017 |
Keywords
- CFD-DEM
- Flow structure
- Fluidization
- Fine ellipsoids
- Interparticle forces
- Orientation
Cite this
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Micromechanical analysis of flow behaviour of fine ellipsoids in gas fluidization. / Gan, J. Q.; Zhou, Z. Y.; Yu, A. B.
In: Chemical Engineering Science, Vol. 163, 18.05.2017, p. 11-26.Research output: Contribution to journal › Article › Research › peer-review
TY - JOUR
T1 - Micromechanical analysis of flow behaviour of fine ellipsoids in gas fluidization
AU - Gan, J. Q.
AU - Zhou, Z. Y.
AU - Yu, A. B.
PY - 2017/5/18
Y1 - 2017/5/18
N2 - The macro-scale flow behaviour of granular materials in gas fluidization is governed by particle-particle and gas-particle interactions, which are affected significantly by particle size and shape. Understanding the micro-scale flow structure of fine non-spherical particles is essential for process design, optimisation and control. In this work, the combined approach of computational fluid dynamics for gas phase and discrete element method for particles is used to study flow and force structures of fine ellipsoids in gas fluidization. The results reveal that fine particles have vortex flow structure in fluidized beds, and the vortex flow becomes more significant particularly for oblate particles. The microscopic structure analysis demonstrates that when aspect ratio deviates from 1.0, the packed beds could experience compaction, and in expanded beds, the bed expansion ratio increases. The effect of particle size is investigated, showing that with the decrease of particle size, the mean coordination number decreases due to more significant role of van der Waals force. Ellipsoids exhibit higher orientation order which varies greatly with gas velocity and particle size. In fluidized beds, ellipsoids tend to flow in small projected area to the fluid flow direction to reduce the flow resistance. The bed expansion criteria established in the literature are confirmed still valid for ellipsoids, but the gas velocity range for expanded bed interval is much wider than spheres.
AB - The macro-scale flow behaviour of granular materials in gas fluidization is governed by particle-particle and gas-particle interactions, which are affected significantly by particle size and shape. Understanding the micro-scale flow structure of fine non-spherical particles is essential for process design, optimisation and control. In this work, the combined approach of computational fluid dynamics for gas phase and discrete element method for particles is used to study flow and force structures of fine ellipsoids in gas fluidization. The results reveal that fine particles have vortex flow structure in fluidized beds, and the vortex flow becomes more significant particularly for oblate particles. The microscopic structure analysis demonstrates that when aspect ratio deviates from 1.0, the packed beds could experience compaction, and in expanded beds, the bed expansion ratio increases. The effect of particle size is investigated, showing that with the decrease of particle size, the mean coordination number decreases due to more significant role of van der Waals force. Ellipsoids exhibit higher orientation order which varies greatly with gas velocity and particle size. In fluidized beds, ellipsoids tend to flow in small projected area to the fluid flow direction to reduce the flow resistance. The bed expansion criteria established in the literature are confirmed still valid for ellipsoids, but the gas velocity range for expanded bed interval is much wider than spheres.
KW - CFD-DEM
KW - Flow structure
KW - Fluidization
KW - Fine ellipsoids
KW - Interparticle forces
KW - Orientation
UR - http://www.scopus.com/inward/record.url?scp=85009872802&partnerID=8YFLogxK
U2 - 10.1016/j.ces.2017.01.020
DO - 10.1016/j.ces.2017.01.020
M3 - Article
VL - 163
SP - 11
EP - 26
JO - Chemical Engineering Science
JF - Chemical Engineering Science
SN - 0009-2509
ER -