A comparative study on the influence of the gas flow rate on the hydrodynamics of a gas-solid spouted fluidized bed using Euler-Euler and Euler-Lagrange/DEM models
Publication date
2014-01
Document type
Research article
Author
Organisational unit
Scopus ID
Publisher
Elsevier
Series or journal
Powder Technology
ISSN
Periodical volume
264
First page
343
Last page
364
Part of the university bibliography
✅
Language
English
Abstract
In this work, different modeling approaches are used to study the hydrodynamics of gas-solid flows in a three-dimensional, lab-scale spouted fluidized bed. In particular, the simulation results obtained by the two-fluid model are compared with those of coupled CFD/DEM simulations. To explore the effects of the gas mass flow rate on the ability of the used simulation techniques to predict the flow behavior in the simulated test case, two different fluidization conditions are considered while maintaining the same computational set-up. The spouted fluidized bed has been evaluated by means of high-speed imaging for validating the simulation results. A comparative study of the two modeling approaches with experimental observations for bubble size in terms of the representative bubble diameter and the bed height has been carried out under both operating conditions. To identify significant simulation settings for the two-fluid model, a parameter study is carried out. The investigated input parameters include the gas-particle drag models, the granular temperature approach, the solid-phase wall boundary conditions in terms of specularity coefficient and the particle-particle restitution coefficient. At a gas mass flow rate of 0.005. kg/s, the predicted characteristics of the bubble formation and the bed expansion using both techniques are in very good agreement with experimental observations. Using the same validated settings, the two-fluid model shows some notable discrepancies when the gas mass flow rate is increased to 0.006. kg/s, while the DEM is more successful than the two-fluid model in reproducing realistic flow patterns. Although both techniques predict the right fluidization regimes and trends in bubble sizes and bed expansion, their results deviate significantly from the experimental data during the final stage of the bubble formation. The most important reasons for the differences in predicting the bed dynamics along with the advantages and limitations of the two approaches are discussed. © 2014 Elsevier B.V.
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