An X-ray system for visualizing fluid flows

Heindel, Theodore J.; Gray, Joseph N.; Jensen, T.

doi:10.1016/j.flowmeasinst.2007.09.003

Cited by 128 publications

(98 citation statements)

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“…Figure 2.11 shows a schematic of this technique. The speed at which images can be acquired, the flexibility in manipulating and storing the images, good temporal and spatial resolution are some of X-ray radiography advantages (Heindel et al, 2008). Heindel et al (2008) applied X-ray radiography to visualize two different multiphase flow systems in a spouted column.…”

Section: X-ray Radiographymentioning

confidence: 99%

“…This can be accomplished by analyzing two images of an object which are taken at different positions either due to a rotation or translation of the sample (Heindel et al, 2008). Figure 2.12 shows a schematic of how X-ray stereography images are acquired.…”

Section: X-ray Stereographymentioning

confidence: 99%

“…The X-ray equipment used in this research is the same as that described by Heindel et al (2008). The equipment consists of two LORAD LPX200 portable X-ray sources.…”

Section: X-ray Equipmentmentioning

confidence: 99%

“…However, in real conditions this ideal situation does not happen and a nonuniform pixel response in the detector is common (Heindel et al, 2008). Therefore, these nonuniformities are corrected to avoid their presence in the resulting CT images which typically produce ring artifacts.…”

Section: Pixel Normalizationmentioning

confidence: 99%

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Bed height and material density effects on fluidized bed hydrodynamics

Escudero

Heindel

2011

Chemical Engineering Science

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Section: X-ray Radiographymentioning

confidence: 99%

Section: X-ray Stereographymentioning

confidence: 99%

“…The X-ray equipment used in this research is the same as that described by Heindel et al (2008). The equipment consists of two LORAD LPX200 portable X-ray sources.…”

Section: X-ray Equipmentmentioning

confidence: 99%

Section: Pixel Normalizationmentioning

confidence: 99%

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Bed height and material density effects on fluidized bed hydrodynamics

Escudero

Heindel

2011

Chemical Engineering Science

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“…Iowa State University's XFloViz facility was used to image the fluidized bed in this study and has been described in detail in the literature [25]. Consequently, only a brief outline will be presented here.…”

Section: Introductionmentioning

confidence: 99%

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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Experimental validation of CFD simulations of a lab‐scale fluidized‐bed reactor with and without side‐gas injection

et al. 2009

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Fluidized-bed reactors are widely used in the biofuel industry for combustion, pyrolysis, and gasification processes. In this work, a lab-scale fluidized-bed reactor without and with side-gas injection and filled with 500-600 lm glass beads is simulated using the computational fluid dynamics (CFD) code Fluent 6.3, and the results are compared to experimental data obtained using pressure measurements and 3D X-ray computed tomography. An initial grid-dependence CFD study is carried out using 2D simulations, and it is shown that a 4-mm grid resolution is sufficient to capture the time-and spatial-averaged local gas holdup in the lab-scale reactor. Full 3D simulations are then compared with the experimental data on 2D vertical slices through the fluidized bed. Both the experiments and CFD simulations without side-gas injection show that in the cross section of the fluidized bed there are two large off-center symmetric regions in which the gas holdup is larger than in the center of the fluidized bed. The 3D simulations using the Syamlal-O'Brien and Gidaspow drag models predict well the local gas holdup variation throughout the entire fluidized bed when compared to the experimental data. In comparison, simulations with the Wen-Yu drag model generally over predict the local gas holdup. The agreement between experiments and simulations with side-gas injection is generally good, where the side-gas injection simulates the immediate volatilization of biomass. However, the effect of the side-gas injection extends further into the fluidized bed in the experiments as compared to the simulations. Overall the simulations under predict the gas dispersion rate above the side-gas injector. V V C 2009 American Institute of Chemical Engineers AIChE J, 56: 1434AIChE J, 56: -1446AIChE J, 56: , 2010 Keywords: biofuel processing, fluidized-bed reactor, gas holdup, multiphase flow, tomography IntroductionFluidized beds are commonly used by the chemical, mineral, pharmaceutical, and energy industries because of low Correspondence concerning this article should be addressed to R. O. Fox at rofox@iastate.edu. PARTICLE TECHNOLOGY AND FLUIDIZATION pressure drops, uniform temperature distributions, and high energy-and mass-transfer rates. In the biofuel industry, fluidized-bed reactors are central components for combustion, pyrolysis, and gasification processes. The local gas holdup (or solids voidage) distribution in the fluidized bed is an extremely important parameter in practical systems, determining the uniform mass and energy distributions and gasification efficiency. Because of the rapid time scales associated with the fluidization dynamics, time-averaged (as opposed to instantaneous) data are often more meaningful than transient data in the design of commercial-scale fluidized-bed reactors.Because the bed material (solid phase) is typically opaque in gas-solid systems, it is difficult to obtain detailed local data (either instantaneous or time-averaged) for the entire bed. As fluidization is a dynamic process, invasive monitoring meth...

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An X-ray system for visualizing fluid flows

Cited by 128 publications

References 50 publications

Bed height and material density effects on fluidized bed hydrodynamics

Bed height and material density effects on fluidized bed hydrodynamics

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

Experimental validation of CFD simulations of a lab‐scale fluidized‐bed reactor with and without side‐gas injection

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