CFD and experimental studies of solids hold-up distribution and circulation patterns in gas–solid fluidized beds

Ahuja, Gaurav; Patwardhan, Ashwin W.

doi:10.1016/j.cej.2008.03.011

Cited by 87 publications

(51 citation statements)

References 61 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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“…Computational fluid dynamics (CFD) has appeared as an effective tool in providing visualized 3 information on flow phenomena in complex geometries at both macroscopic and microscopic level [10,11]. Yamaguchi et al [11] applied CFD to simulate laminar co-flow in a microchannel with hairpin bends and the simulation results were consistent with experimental data.…”

Section: Introductionsupporting

confidence: 65%

Production of polymeric nanoparticles by micromixing in a co-flow microfluidic glass capillary device

Othman

Vladisavljević

Bandulasena

et al. 2015

Chemical Engineering Journal

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“…These results evidence a clear resemblance in the particle recirculation patterns obtained in simulation and experiments, but it appears that the simula tions over predict the modulus of the particle velocity vectors for small superficial velocities (U/U mf ¼1.65 in Lindborg et al, 2007), and that the prediction of the vertical position of the recirculation centre is not completely satisfactory (Hosseini et al, 2010). Ahuja and Patwardhan (2008), for U/U mf ¼5.6, as well as Wang and Liu (2010), this last study using FCC particles, compared their two dimensional simulation results with three dimensional experiments and found acceptable agreement in the radial pro files of velocity. Very recently, Li et al (2010) compared the experimental results from the work done by Laverman et al (2008) in a pseudo 2D fluidized bed with 2D and 3D simulations using the drag model of Gidaspow.…”

Section: Introductionmentioning

confidence: 73%

Comparison between two-fluid model simulations and particle image analysis & velocimetry (PIV) results for a two-dimensional gas–solid fluidized bed

Hernández-Jiménez

Sánchez-Delgado

Gómez-García

et al. 2011

Chemical Engineering Science

109

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a b s t r a c tThis work compares simulation and experimental results of the hydrodynamics of a two dimensional, bubbling air fluidized bed. The simulation in this study has been conducted using an Eulerian Eulerian two fluid approach based on two different and well known closure models for the gas particle interaction: the drag models due to Gidaspow and Syamlal & O'Brien. The experimental results have been obtained by means of Digital Image Analysis (DIA) and Particle Image Velocimetry (PIV) techniques applied on a real bubbling fluidized bed of 0.005 m thickness to ensure its two dimensional behaviour. Several results have been obtained in this work from both simulation and experiments and mutually compared. Previous studies in literature devoted to the comparison between two fluid models and experiments are usually focused on bubble behaviour (i.e. bubble velocity and diameter) and dense phase distribution. However, the present work examines and compares not only the bubble hydrodynamics and dense phase probability within the bed, but also the time averaged vertical and horizontal component of the dense phase velocity, the air throughflow and the instantaneous interaction between bubbles and dense phase. Besides, quantitative comparison of the time averaged dense phase probability as well as the velocity profiles at various distances from the distributor has been undertaken in this study by means of the definition of a discrepancy factor, which accounts for the quadratic difference between simulation and experiments The resulting comparison shows and acceptable resemblance between simulation and experiments for dense phase probability, and good agreement for bubble diameter and velocity in two dimensional beds, which is in harmony with other previous studies. However, regarding the time averaged velocity of the dense phase, the present study clearly reveals that simulation and experiments only agree qualitatively in the two dimensional bed tested, the vertical component of the simulated dense phase velocity being nearly an order of magnitude larger than the one obtained from the PIV experiments. This discrepancy increases with the height above the distributor of the two dimensional bed, and it is even larger for the horizontal component of the time averaged dense phase velocity. In other words, the results presented in this work indicate that the fine agreement commonly encountered between simulated and real beds on bubble hydrodynamics is not a sufficient condition to ensure that the dense phase velocity obtained with two fluid models is similar to that from experimental measurements on two dimensional beds.

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CFD and experimental studies of solids hold-up distribution and circulation patterns in gas–solid fluidized beds

Cited by 87 publications

References 61 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

Production of polymeric nanoparticles by micromixing in a co-flow microfluidic glass capillary device

Comparison between two-fluid model simulations and particle image analysis & velocimetry (PIV) results for a two-dimensional gas–solid fluidized bed

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