Computational fluid dynamics for dense gas-solid fluidized beds

Zhang, Kai; Brandani, Stefano; Ji-cheng, BI

doi:10.1080/10020070512330006

Cited by 20 publications

(8 citation statements)

References 18 publications

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“…The linear equation for each variable is solved by Block Stone's method in the inner iteration. To prevent particle concentration from exceeding its physical limitation, a method for the reconstruction of the excess solid concentration together with a correction to the corresponding momentum equations is employed to be compatible with CFX 4.4 soft package (Zhang, Brandani et al (2002); Zhang et al, 2005;Brandani & Zhang, 2006;Zhang & Brandani, 2004Pei et al, 2008;Pei, Zhang, Lu, & Wen, 2009). …”

Section: Numerical Simulationmentioning

confidence: 99%

“…The accuracy of the numerical prediction is strongly affected by the choice of particle-phase viscosity model. However, there is still no consensus on the particle-phase viscosity in the solid momentum equation of the Eulerian-Eulerian model (Agrawal, Loezos, Syamlal, & Sundaresan, 2001;Li et al, 2005;Patil, van Sint Annaland, & Kuipers, 2005;Zhang, Brandani, & Bi, 2005). The particle-phase viscosity is generally defined by three approaches: (i) as a constant of 1.0 based on experimental data of Grace (1970) (Gidaspow & Ettehadleh, 1983;Kuipers, 1990;Hong, Li, Cheng, & Zhang, 1996;Zhang, Zhang, Lovick, Zhang, & Zhang, 2002); (ii) as a constant value of zero (Needham & Merkin, 1983;Chen, Gibilaro, & Foscolo, 1999;Gibilaro, 2001;Chen, Gibilaro, & Jand, 2003;Wang et al, 2007;Pei, Wang, Zhang, & Wen, 2008), and (iii) as a function of the granular temperature obtained from the kinetic theory (Ding & Gidaspow, 1990;Hong, Guo, Luo, Zhang, & Ding, 2003;Hong, Ding, & Li, 2005;Patil et al, 2005).…”

Section: Introductionmentioning

confidence: 98%

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CFD simulation of a gas–solid fluidized bed with two vertical jets

et al. 2010

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Section: Numerical Simulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

CFD simulation of a gas–solid fluidized bed with two vertical jets

et al. 2010

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“…In order to use RFMBRs more effectively and understand the gas-solid flow behavior, an understanding hydrodynamics of RFMBRs via numerical modeling is necessary [9,10]. The CFD approach as an emerging technique holds great potential in providing detailed information of the complex fluid dynamics [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

A Two-Phase CFD Modeling Approach to Investigate the Flow Characteristics in Radial Flow Moving-Bed Reactors

Xiao

Luo²

2014

International Journal of Chemical Reactor Engineering

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Based on a complete CFD Eulerian-Eulerian two-fluid approach, a comprehensive three-dimensional (3D) two-phase reactor model was suggested to describe the flow behavior in radial flow moving-bed reactors (RFMBRs). A porous media model was incorporated into the reactor model in order to describe the flow resistance provided by the porous walls of the center and annular pipes. Compared with these previous reactor models, the reactor model considers the solid-phase movement instead of immobilization, which benefits for predicting the formation of cavity practically. The simulation results are agreement with the published experimental data. By employing the verified model, the flow field parameters in the reactors such as pressure drop and flow velocity were obtained. Besides, the simulations were then carried out to investigate the effect of the bed voidage on the flow behavior and to understand the phenomenon of cavity in the RFMBRs. The simulation results showed that both the centripetal and the centrifugal flow configurations have the inhomogeneous flow distribution and the phenomenon of cavity. Furthermore, the inhomogeneous distribution increases with the increase of the bed voidage, whereas the phenomenon of cavity is more obvious with the increase of gas inlet velocity. As a whole, this work provided a realistic modeling and a useful approach for the understanding of RFMBRs.

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“…van Wachem et al (2001) suggested that CFD model based on the Eulerian–Eulerian framework was the only feasible approach for performing parametric investigations and scale‐up and design studies. However, there is still no consensus on solid‐phase viscosity, solid stress modulus, and particle restitution coefficient in the above Eulerian–Eulerian models (Gibilaro, 2001; Zhang et al, 2005). It drove several researchers to develop different models for describing the hydrodynamics in fluidized beds (Gibilaro, 2001; Chen et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…Recently, Zhang and Brandani (2004) and Brandani and Zhang (2006) derived a hydrodynamic model without solid viscosity starting from the finite formulation of the two‐fluid theory and included the effect of the discrete nature of the particles when taking the limit to obtain the continuum formulation. The model has been used to investigate transient and time‐averaged gas and solid dynamics in gas–solid JFBs by Zhang et al (2005) and Wang et al (2007). The simulated results were in agreement with those reported in the literature.…”

Section: Introductionmentioning

confidence: 99%

Scale‐up strategy for the jetting fluidized bed using a CFD model based on two‐fluid theory

et al. 2009

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Based on a hydrodynamic two-fluid model [Brandani and Zhang, Powder Technol. 2006; 163(1-2): 80-87], the scaling relations developed by Glicksman et al., are modified to improve the understanding of the scale-up of jetting fluidized beds (JFBs). To estimate the ability of the proposed scaling rules to give similar results, simulations are conducted in CFX 4.4. We investigate in detail the effects of jet gas velocity on the scale-up rule. The similarities of jet evolutions and time-averaged radial viodage distributions are compared between large and small beds. The computational results confirm that the modified scaling rules are valid for JFBs when all dimensionless groups are matched between the prototype and large-scale beds.A partir d'un modèle hydrodynamiqueà deux fluides (Brandani and Zhang, 2006), les relations d'échelleélaborées par Glicksman et al. sont modifiées de façonà améliorer la compréhension de l'extrapolation des lits fluidisésà jet (JFD). Pour valider les règles de miseà l'échelle proposées, des simulations sont menées avec le code CFX 4.4. Nousétudions en détail les effets de la vitesse de gaz de jet sur la règle d'extrapolation. Les similitudes dans l'évolution de jets et les distributions de vide radiales moyennées en temps sont comparées entre les grands et les petits lits. Les résultats des calculs par ordinateur confirment que les règles de miseà l'échelle modifiées sont valides pour les JFD lorsque tous les groupes adimensionnels entre les lits prototypes et les lits de grandeéchelle sontégaux.

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Computational fluid dynamics for dense gas-solid fluidized beds

Cited by 20 publications

References 18 publications

CFD simulation of a gas–solid fluidized bed with two vertical jets

CFD simulation of a gas–solid fluidized bed with two vertical jets

A Two-Phase CFD Modeling Approach to Investigate the Flow Characteristics in Radial Flow Moving-Bed Reactors

Scale‐up strategy for the jetting fluidized bed using a CFD model based on two‐fluid theory

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