Computational fluid dynamics (CFD) modeling of spouted bed: Assessment of drag coefficient correlations

Du, Wei; Bao, Xiaojun; Xu, Jian; Wei, Weisheng

doi:10.1016/j.ces.2005.08.013

Cited by 227 publications

(144 citation statements)

References 56 publications

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“…The experimental data and 3D simulations are local time-average values along a ray that passes through the centerline of the bed and side injection port at the given z height. The variations in the experimental data are attributed to the non-uniform inlet conditions that result from the 62 discrete air inlet holes of the distributor plate, and similar discrepancies have been shown by others [36][37][38][39]. The 3D prediction compares very well with the experiment, whereas the 2D simulation significantly overpredicts the presence of gas near the lower region of the bed (Fig.…”

Section: Two-and Three-dimensional Simulationssupporting

confidence: 62%

Effects of Mixing Using Side Port Air Injection on a Biomass Fluidized Bed

Deza

Heindel

Battaglia

2011

Journal of Fluids Engineering

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Fluidized beds are being used in practice to gasify biomass to create producer gas, a flammable gas that can be used for process heating. However, recent literature has identified the need to better understand and characterize biomass fluidization hydrodynamics, and has motivated the combined experimental-numerical effort in this work. A cylindrical reactor is considered and a side port is introduced to inject air and promote mixing within the bed. Comparisons between the computational fluid dynamics (CFD) simulations with experiments indicate that three-dimensional simulations are necessary to capture the fluidization behavior of the more complex geometry. This paper considers the effects of increasing side port air flow on the homogeneity of the bed material in a 10.2 cm diameter fluidized bed filled with 500-600 μmground walnut shell particles. The use of two air injection ports diametrically opposed to each other is also modeled using CFD to determine their effects on fluidization hydrodynamics. Whenever possible, the simulations are compared to experimental data of time-average local gas holdup obtained using X-ray computed tomography. This study will show that increasing the fluidization and side port air flows contribute to a more homogeneous bed. Furthermore, the introduction of two side ports results in a more symmetric gas-solid distribution.

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Section: Two-and Three-dimensional Simulationssupporting

confidence: 62%

Effects of Mixing Using Side Port Air Injection on a Biomass Fluidized Bed

Deza

Heindel

Battaglia

2011

Journal of Fluids Engineering

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“…We note that Eq. (28) is not valid for dense transport regimes like sheet flow, in which the drag coefficient displays a strong dependence on the concentration profile of transported particles [36]. In this manner, Eq.…”

Section: Height-integrated Conservation Equationsmentioning

confidence: 99%

“…(41) requires obtaining an expression for dΩ/dV , where Ω(V ) is defined in Eq. (36). However, Ω(V ) incorporates, through the function B(V ) defined in Eq.…”

Section: A Derivationmentioning

confidence: 99%

Analytical model for flux saturation in sediment transport

et al. 2014

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The transport of sediment by a fluid along the surface is responsible for dune formation, dust entrainment and for a rich diversity of patterns on the bottom of oceans, rivers, and planetary surfaces. Most previous models of sediment transport have focused on the equilibrium (or saturated) particle flux. However, the morphodynamics of sediment landscapes emerging due to surface transport of sediment is controlled by situations out-of-equilibrium. In particular, it is controlled by the saturation length characterizing the distance it takes for the particle flux to reach a new equilibrium after a change in flow conditions. The saturation of mass density of particles entrained into transport and the relaxation of particle and fluid velocities constitute the main relevant relaxation mechanisms leading to saturation of the sediment flux. Here we present a theoretical model for sediment transport which, for the first time, accounts for both these relaxation mechanisms and for the different types of sediment entrainment prevailing under different environmental conditions. Our analytical treatment allows us to derive a closed expression for the saturation length of sediment flux, which is general and can thus be applied under different physical conditions.

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“…It is well known that in fluidized beds, particles interact strongly with the gas flow, and consequently the drag model implemented affects the predicted particle motion, as well as the CTD and RTD. In the assessment of drag models by Du W. et al (2006) based on the two-fluid model (TFM), the Gidaspow drag model (Gidaspow D., 1994) gave the best agreement with experimental observations in modeling of spouted beds. With the recent increase in computational power, it has become feasible to derive the drag model by fully solving the flow between particles (Kriebitzsch S.H.L.…”

Section: Introductionmentioning

confidence: 99%

“…Later, Gidaspow D. (1994) suggested a model based on the Ergun equation for the dense regime and the Wen-Yu correlation for the dilute regime. The modification made by Gidaspow D. was found to be the best in modeling of spouted beds (Du W. et al, 2006) and has been widely used in engineering practice (Deen N.G. et al, 2007).…”

Section: Drag Modelsmentioning

confidence: 99%

Effect of Drag Models on Residence Time Distributions of Particles in a Wurster Fluidized Bed: a DEM-CFD Study

Remmelgas

Wachem

et al. 2016

KONA

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Fluidized bed coating has been used to coat pellets or tablets with functional substances for a number of purposes. In this coating process, particle wetting, drying and film formation are coupled to particle motion. It is therefore of interest to study particle motion in such fluidized beds and to use the results to develop a model for predicting the quality of the final product. In this paper, we present results from DEM-CFD simulations, i.e. discrete element method and computational fluid dynamics simulations of particle motion in a laboratory-scale Wurster fluidized bed that was also employed in positron emission particle tracking (PEPT) experiments. As the drag force is the dominant interaction between the gas flow and the particle motion in this type of fluidized bed, the effect of drag models on the particle motion is investigated. More specifically, the particle velocity and residence time distributions of particles in different regions calculated from five different drag models are presented. It is found that the Gidaspow and Tang drag models predict both particle cycle and residence times well. The HKL and Beetstra drag models somewhat overestimate the particle velocity in the Wurster tube and therefore predict a reduced number of recirculations and a significantly shorter cycle time.

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Computational fluid dynamics (CFD) modeling of spouted bed: Assessment of drag coefficient correlations

Cited by 227 publications

References 56 publications

Effects of Mixing Using Side Port Air Injection on a Biomass Fluidized Bed

Effects of Mixing Using Side Port Air Injection on a Biomass Fluidized Bed

Analytical model for flux saturation in sediment transport

Effect of Drag Models on Residence Time Distributions of Particles in a Wurster Fluidized Bed: a DEM-CFD Study

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