Novel Approach to Characterize Fluidized Bed Dynamics Combining Particle Image Velocimetry and Finite Element Method

Almendros-Ibáñez, J.A.; Pallarès, David; Johnsson, Filip; Santana, D.

doi:10.1021/ie801720g

Cited by 5 publications

(4 citation statements)

References 33 publications

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“…Having the Davidson's model as basis, Almendros Ibáñez et al [35] obtained a flow crossing the bubble of q b =4 · U 0 · R b , agreeing with the analytical result obtained by Davidson [2]. Fig.…”

Section: Influence Of Voidage Variation On the Gas Flow Through A Bubblesupporting

confidence: 78%

“…The numerical scheme was verified against the simplest case of an isolated circular bubble, which was analysed previously by Almendros Ibáñez et al [35]. Having the Davidson's model as basis, Almendros Ibáñez et al [35] obtained a flow crossing the bubble of q b =4 · U 0 · R b , agreeing with the analytical result obtained by Davidson [2].…”

Section: Influence Of Voidage Variation On the Gas Flow Through A Bubblesupporting

confidence: 74%

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Voidage distribution around bubbles in a fluidized bed: Influence on throughflow

et al. 2010

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a b s t r a c tIn this work, a new method for measuring void fraction distribution around endogenous bubbles in a 2D fluidized bed is presented. The technique is based on illuminating a transparent wall 2 dimensional bed with diffuse light from the rear and recording the distribution of light that penetrates the bed. The recording is made with a high speed video camera, which gives frames with grey level corresponding to the light penetration and from which the voidage distribution around the bubbles can be determined. In this way, voidage distribution in the region very close to the bubble contour (r/R b ≲ 1.2) is obtained, which was not possible in previous studies due to limitations in spatial resolution. A correlation is proposed for the voidage at the contour of the bubble, with the voidage depending on the radial position and the polar angle ε(r, θ). In addition, the effect of the voidage distribution on the throughflow crossing the bubbles was studied and an increase of 20% was determined for the average bubble geometry of the more than 100 bubbles analysed.

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Section: Influence Of Voidage Variation On the Gas Flow Through A Bubblesupporting

confidence: 78%

Section: Influence Of Voidage Variation On the Gas Flow Through A Bubblesupporting

confidence: 74%

Voidage distribution around bubbles in a fluidized bed: Influence on throughflow

et al. 2010

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“…In addition, Shen et al [14] and Busciglio et al [15] measured the size and velocity of bubbles along the height of the bed, and Santana et al [16], Müller et al [17] and Almendros Ibáñez et al [18] applied Particle Image Velocimetry (PIV) to obtain the instantaneous particle velocity around erupting bubbles in 2D fluidized beds. Similarly, Almendros Ibáñez et al [19] combined PIV techniques with numerical calculations to characterize particle fluid motion around bubbles, and Link et al [20] and Busciglio et al [21] compared the experimental results obtained in 2D fluidized beds to those of numerical simulations.…”

Section: Introductionmentioning

confidence: 99%

On the minimum fluidization velocity in 2D fluidized beds

et al. 2011

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a b s t r a c tIn the present study, a new correlation for the determination of the minimum fluidization velocity in 2D fluidized beds was developed. The proposed correlation was based on the experimental results obtained in 2D fluidized beds with different particle sizes, bed thicknesses and bed heights. Thus, the proposed correlation depends only on the nondimensional variable t/d p , where t is the bed thickness and d p is the particle size. The proposed correlation was compared with other experimental results that can be found in the literature, and two different trends were observed. Namely, one set of experimental results was in accordance with the proposed correlation, while the other set deviated from the theoretical results. In particular, the minimum fluidization velocities of the experimental results were greater than the predicted values of the proposed correlation. In view of the differences in the experimental conditions, the observed discrepancies may be attributed to the effects of electrostatic charge and particle shape. In addition, the experimental fluidization defluidization curves were compared to the theoretical results of Jackson's model, and the parameters were fitted to the experimental data. However, Jackson's model is based on a 1D bed; thus, general parameters could not be obtained for a bed with a fixed particle size and thickness due to the two dimensional voidage distribution in the bed and bed cohesion effects, which are a result of electrostatic forces and are not considered in Jackson's model.

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“…The velocity vector of the bubble centroid forms an angle Â b with the positive vertical direction [25]. In this work the angle Â b shall be termed the direction of bubble rise.…”

Section: Theoretical Models For Particle Ejectionmentioning

confidence: 99%

Comparison of bubble eruption models with two-fluid simulations in a 2D gas-fluidized bed

Hernández-Jiménez

Third

Acosta-Iborra

et al. 2011

Chemical Engineering Journal

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a b s t r a c tTwo-fluid simulations of gas-solid fluidized beds are performed in this work with a threefold aim: (1) explore the capabilities of two-fluid modelling to reproduce realistically bubble eruption patterns in two-dimensional fluidized beds; (2) compare the results obtained from the two-fluid simulations with particle ejection models; and (3) provide information about the mutual interaction of the gas and particle flows during bubble eruption. To fulfil these aims, results from two-fluid simulations concerning the vertical and horizontal velocities of particles in bubble domes, prior to and during bubble eruption, are reported and compared with previously published experimental data taken from a bed of comparable geometry and operating conditions. The comparison shows excellent quantitative agreement. Particle ejection velocities estimated through semi-empirical and theoretical models proposed in the literature are compared with the particle behaviour in the bubble dome obtained from the two-fluid simulations. The results obtained here indicate that the theory based on the potential flow around a cylinder provides a more accurate prediction for the particle velocities in erupting bubbles than semi-empirical relations. For the data reported here it has been found that the velocity of particles in the bubble dome forms an angle with the vertical direction that is twice the angle formed by the radial direction. This observation is contrary to standard models of 2D bubbles, which assume that the particles are ejected radially outwards from the dome.

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Novel Approach to Characterize Fluidized Bed Dynamics Combining Particle Image Velocimetry and Finite Element Method

Cited by 5 publications

References 33 publications

Voidage distribution around bubbles in a fluidized bed: Influence on throughflow

Voidage distribution around bubbles in a fluidized bed: Influence on throughflow

On the minimum fluidization velocity in 2D fluidized beds

Comparison of bubble eruption models with two-fluid simulations in a 2D gas-fluidized bed

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