The effect of friction and inter-particle cohesive forces on the hydrodynamics of gas–solid flow: A comparative analysis of theoretical predictions and experiments

Makkawi, Yassir; Wright, Phillip C.; Ocone, Raffaella

doi:10.1016/j.powtec.2006.01.020

Cited by 80 publications

(49 citation statements)

References 19 publications

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“…Figure 5.5 and 5.6 shows the time averaged particle volume fractions along the radial direction. High particle volume fraction near the walls due to segregation observed in experiments [95] is well predicted by current CFD simulations.…”

Section: Verification and Validationsupporting

confidence: 77%

Computational fluid dynamic modeling of fluidized-bed polymerization reactors

Rokkam

2012

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Section: Verification and Validationsupporting

confidence: 77%

Computational fluid dynamic modeling of fluidized-bed polymerization reactors

Rokkam

2012

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“…This model is referred to in MFIX documentation as the Schaeffer model. In that model, the transition between the kinetic and the plastic regimes is thus rather abrupt and could lead, according to Makkawi et al (2006), to inaccurate predictions of bubble shape and bed expansion in some specific cases (intermediate to high gas velocities). Another model proposed by Srivastava and Sundaresan (2003) is often called the Princeton model (Benyahia et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Multifluid Eulerian modeling of dense gas–solids fluidized bed hydrodynamics: Influence of the dissipation parameters

Reuge

Cadoret

Coufort-Saudejaud

et al. 2008

Chemical Engineering Science

131

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Computational fluid dynamic (CFD) models must be thoroughly validated before they can be used with confidence for designing fluidized bed reactors. In this study, validation data were collected from a fluidized bed of (Geldart's group B) alumina particles operated at different gas velocities involving two fluidization hydrodynamic regimes (bubbling and slugging). The bed expansion, height of bed fluctuations and frequency of fluctuations were measured from videos of the fluidized bed. The Eulerian-Eulerian two fluid model MFIX was used to simulate the experiments. Two different models for the particle stresses-Schaeffer [Syamlal, M., Rogers, W., O'Brien, T.J., 1993. MFIX documentation: theory guide. Technical Report DOE/METC-94/1004 (DE9400087), Morgantown Energy Technology Centre, Morgantown, West Virginia (can be downloaded from Multiphase Flow with Interphase eXchanges (MFIX) website http://www.mfix.org ); Schaeffer, D.G., 1987. Instability in the evolution equations describing incompressible granular flow. Journal of Differential Equations 66, 61-74.] and Princeton [Srivastava, A., Sundaresan, S., 2003. Analysis of a frictional-kinetic model for gas-particle flow. Powder Technology 129(1-3), 72-85.] models-and different values of the restitution coefficient and internal angle of friction were evaluated. 3-D simulations are required for getting quantitative and qualitative agreement with experimental data.The results from the Princeton model are in better agreement with data than that from the Schaeffer model. Both free slip and Johnson-Jackson boundary conditions give nearly identical results. An increase in coefficient of restitution (e) from 0.8 to 1 leads to larger bed expansions and lower heights of fluctuations in the bubbling regime, whereas it leads to unchanged bed expansion and to a massive reduction in the height of fluctuations in the slugging regime. The angle of internal friction () in the range 10-40 • does not affect the bed expansion, but its reduction significantly reduces the height of fluctuations.

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“…The viscosities obtained from the Gidaspow [24] and Benyhia [26] ϕ A possible explanation for observed plateauing or decreasing trend at higher solid volume fractions is the frictional stresses which are not included in current granular models. Work of Makkawi et al [36] clearly demonstrates importance of the frictional stresses in the whole range of solid volume fraction in a gas-FB. However, it is impossible to estimate the frictional part of granular viscosity without detailed simulation or comparison with direct measurement using viscometers, which is planned by us in the near future.…”

Section: Granular Viscositymentioning

confidence: 95%