Particle shape effect on bubble dynamics in central air jet pseudo-2D fluidized beds: A CFD-DEM study
Autor: | Siddhartha Shrestha, Aibing Yu, Shibo Kuang, Zongyan Zhou |
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Rok vydání: | 2019 |
Předmět: |
Coalescence (physics)
Materials science Applied Mathematics General Chemical Engineering Bubble 02 engineering and technology General Chemistry Mechanics 021001 nanoscience & nanotechnology Industrial and Manufacturing Engineering Physics::Fluid Dynamics 020401 chemical engineering Fluidized bed SPHERES Fluidization Liquid bubble Particle velocity 0204 chemical engineering 0210 nano-technology CFD-DEM |
Zdroj: | Chemical Engineering Science. 201:448-466 |
ISSN: | 0009-2509 |
Popis: | Bubbles considerably influence the characteristics of gas-solid fluidized bed, hence play an important role in determining process performance. This paper presents a CFD-DEM study on the effect of particle shape on the bed microstructure and bubble properties in a pseudo-2D bubbling gas-solid fluidized bed, operated with a continuous central jet. The bubble formation process is successfully generated, where bubbles rise through the bed and burst at the top of the bed. The numerical results show that ellipsoids have slightly different flow patterns from those of spheres. However, the mechanisms of bubble splitting and coalescence are found strongly dependent on particle shape. For spheres, the bubble trajectories mainly follow the bed centreline, whereas the bubbles for ellipsoids are widely distributed on both sides of the bed centreline. This result suggests that the lateral drift of bubbles is high for ellipsoids because such particles prefer to orient their longest major axis in the direction of the fluid flow. At the lower part of the bed, both gas and particle velocity profiles are found axially similar to a Gaussian distribution. In contrast, at the upper part of the bed, their peaks become flatter and broader for ellipsoids. Additionally, the bubble equivalent diameters are higher for ellipsoids while bubbles become more circular for spheres. Both bubble frequency and bubble velocity for ellipsoids are lower than spheres. The results obtained from this study can improve the understanding of bubble dynamics in the fluidization of non-spherical particles. |
Databáze: | OpenAIRE |
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