Interparticle stress, fluid pressure, and bubble motion in gas-fluidised beds

Clift, Roland; Rafailidis, S.V.

doi:10.1016/0009-2509(93)80117-9

Cited by 16 publications

(4 citation statements)

References 26 publications

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“…Figure 6 shows that the spherical cap together with its wake is nearly a complete sphere, which justifies our method of determining the wake fraction. It is a question whether the toroidal flow pattern seen in the wake also reflects the actual dynamics precisely (see Clift and Rafailidis (1993)).…”

Section: Resultsmentioning

confidence: 99%

“…Grace (1970) investigated the rheology of the dense phase of fluidized beds on the basis of the shape of fluidization bubbles and Murray (1967) and on the basis of terminal velocities. The nature of fluidized particles and fluidization bubbles has been discussed extensively in the scientific literature (see, for instance, Collins (1965Collins ( , 1989 and Clift and Rafailidis (1993).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Numerical Model of the Flow Past a Spherical-Cap Bubble Rising in a Fluidized Bed

Hoogstraten¹,

Rass²,

Hartholt³

et al. 1998

Ind. Eng. Chem. Res.

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The shape and motion of gas bubbles in a fluidized bed are investigated by considering a single spherical-cap bubble rising vertically with free slip at its surface in an incompressible Newtonian fluid. The bubble shape, its terminal rise velocity, and the flow pattern around the bubble have been computed numerically by use of a finite element package solving the Navier-Stokes flow equations. Comparison with experimental findings shows that the bubble shape and the wake fraction can be predicted satisfactorily for a range of bubble sizes by assuming that the fluidized bed behaves as a Newtonian fluid. However, a clear-cut discrepancy was found in the terminal rise velocity. The results indicate that this discrepancy cannot be fully explained from the a priori assumption of the spherical-cap bubble shape, but that, most probably, some nonNewtonian fluid behavior must be invoked.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Numerical Model of the Flow Past a Spherical-Cap Bubble Rising in a Fluidized Bed

Hoogstraten¹,

Rass²,

Hartholt³

et al. 1998

Ind. Eng. Chem. Res.

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“…The bubble wakes impact on these horizontal disks (Clift & Rafailidis 1993). Thus, the wakes of rising bubbles lose their wake particles and thereafter new wakes form above the disk=baffle.…”

Section: Artificial Neural Network Approach To Segregation 583mentioning

confidence: 99%

Artificial Neural Network Approach to Segregation Characteristic of Binary Heterogeneous Mixtures in Promoted Gas-Solid Fluidized Beds

Sahoo¹,

Roy²

2008

Particulate Science and Technology

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Binary mixtures of particles of the same size but of different densities are fluidized in a 15 cm diameter column with a perforated plate distributor and two coaxial promoters. In the present work an attempt has been made to study the fluidization and the segregation characteristic of density-variant solids of the same size in terms of segregation distance. The dimensionless segregation distance has been correlated with other dimensionless groups relating to various system parameters: ratio of the density of jetsam particles to that of flotsam, initial static bed height, height of layer of particles above the bottom grid, superficial gas velocity, and average density of the mixture on the basis of the dimensional analysis approach for both un-promoted and promoted beds. Correlations have also been developed with the above system parameters by using an artificial neural network approach for different types of fluidized beds, and the findings with respect to both approaches have been compared with each other. The values of segregation distance for promoted beds have also been compared with those for the un-promoted bed in this work.

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“…However, this research involving moving granular filter beds neglected the effect of the interstitial fluid flow relative to the granules. A variety of theoretical, numerical and experimental methods have been implemented to explore the behavior of gas-solid flows in dense-phase fluidized beds [11][12][13][14][15][16][17][18][19][20], circulating fluidized beds [21][22][23][24][25][26], and pneumatic conveying [1,[27][28][29][30][31][32][33][34][35][36][37]. However, little attention has been paid to the effect of inlet gas velocity on the flow behavior of granular material in a moving granular filter bed with a symmetric louvered-wall.…”

Section: Introductionmentioning

confidence: 99%

Gas‐Solid Flow in a Two‐Dimensional Cross‐Flow Moving Granular Filter Bed with a Symmetric Boundary

Chou

Lee

Yeh

2007

Part & Part Syst Charact

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This study investigates how the inlet gas velocity and the louver angle affect the granular flow of spherical particles in two-dimensional moving (and fixed) granular filter beds with a symmetric louvered-wall. The methodology of Tsuji et al. [1] was extended to facilitate this gas-solid flow field calculation. The calculation procedures were as follows: (1) determination of the coordinates of each spherical particle and calculation of the void fraction of the granular bed; (2) calculation of the updated two-dimensional gas velocity field using the SIMPLE method [2]; (3) determination of the drag force acting on the particle using the equation of Fan and Zhu [3], and (4) obtaining the contact force, velocity and displacement of each particle using the DEM model devised by Cundall and Starck [4]. In addition, a digital camcorder was used to record the flow pattern histories of the spherical particles in cross-flow moving (and fixed) granular filter beds with a symmetric louveredwall. The numerical predictions were compared with the experimental results in a qualitative manner. In a fixed granular bed, the bubble area obtained, which is based on numerical predictions agrees with that obtained experimentally, and increases with louver angle. However, in a moving granular bed, the bubble area obtained by numerical modeling increases with louver angle, but the bubble area obtained experimentally decreases with increasing louver angle. Additionally, this investigation demonstrates both numerically and experimentally that the bubble area increases with air inlet velocity in both fixed and moving granular beds.

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Interparticle stress, fluid pressure, and bubble motion in gas-fluidised beds

Cited by 16 publications

References 26 publications

A Numerical Model of the Flow Past a Spherical-Cap Bubble Rising in a Fluidized Bed

A Numerical Model of the Flow Past a Spherical-Cap Bubble Rising in a Fluidized Bed

Artificial Neural Network Approach to Segregation Characteristic of Binary Heterogeneous Mixtures in Promoted Gas-Solid Fluidized Beds

Gas‐Solid Flow in a Two‐Dimensional Cross‐Flow Moving Granular Filter Bed with a Symmetric Boundary

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