Analysis of gas‐fluidized solid systems by x‐ray absorption

Grohse, E. W.

doi:10.1002/aic.690010315

Cited by 68 publications

(30 citation statements)

References 6 publications

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“…As indicated above, a bubble-free bed may not be ideal from all points of view, since particle movement in a gas-fluidized bed does not occur in the absence of gas bubbles. (2)(3)(4) The value of some early theoretical studies of bed quality!^ >5,6) was reduced by the nonavailability to their authors of some of the more recent studies of the actual nature of gas-fluidized beds, and by acceptance 13 of Wilhelm and Kwauk's term "aggregative fluidization" to describe such beds. The most valuable contribution was that of Rice and WilhelmV^j who developed a set of equations governing the stability of bed-fluid "interfaces" (although they decided that it -was the upper surface of a bubble that was \ (7 8^ unstable).…”

Section: Quality Of Fluidizationmentioning

confidence: 99%

The Effect of Particle Size on the Properties of Gas-Fluidized Beds

Sutherland¹

1964

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Section: Quality Of Fluidizationmentioning

confidence: 99%

The Effect of Particle Size on the Properties of Gas-Fluidized Beds

Sutherland¹

1964

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“…One of the first applications of X-ray imaging for visualisation of air bubbles in gas-solid fluidised beds was performed in the 1950s and 1960s (Grohse 1955;Rowe and Partridge 1997). A variety of tomographic, or 2-D radiographic, X-ray techniques have been developed, where tomography refers to the cross-sectional imaging of a system from either transmission or reflection data collected by illumination of the flow system from many different angles (Kak and Slaney 2001), while radiography refers to single-angle collection data.…”

Section: Introductionmentioning

confidence: 99%

Application of X-ray micro-computed tomography on high-speed cavitating diesel fuel flows

et al. 2016

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efficiency of such engines. Among others, the fuel injection equipment (FIE) is a key component for improving the efficiency of environmentally friendly engines. Recent advances dictate the use of extra high injection pressures, of the order of 3000 bar and tiny flow passages (injection holes) of the order of 100-250 μm in diameter, for improved fuel atomisation and combustion efficiency. Under these circumstances, cavitation has been found to develop inside fuel injection nozzles at the early studies of Badock et al. (1999), Bergwerk (1959), Chaves et al. (1995) and Nurick (1976), followed by Arcoumanis et al. (2000), Blessing et al. (2003), Mitroglou et al. (2014) and Roth et al. (2002) in more realistic real-size nozzle geometries offering optical access; equally helpful studies performed in transparent enlarged nozzle replicas [selectively (Andriotis et al. 2008;Arcoumanis et al. 2000;Miranda et al. 2003; Mitroglou and Gavaises 2013;Powell et al. 2000)] also indicate that cavitation plays an increasingly significant role in the nozzle's internal flow structure and development. Cavitation inside an injection hole is believed to enhance spray atomisation, either directly through the implosion of cavitation bubbles or indirectly because it increases turbulence in the nozzle flow (Badock et al. 1999;Walther 2002); unfortunately, under certain circumstances induces erosion (Dular and Petkovšek 2015;Koukouvinis et al. 2016) that may lead to catastrophic failures. Moreover, cavitation inside the injection holes promotes shot-toshot spray instabilities (Mitroglou et al. 2011(Mitroglou et al. , 2012Suh and Lee 2008), which, in turn, are responsible for poor combustion efficiency and increased emissions (Hayashi et al. 2013). Two distinct macroscopic forms of cavitation have been identified, which are referred to as geometryinduced and vortex or 'string' cavitation. The former can be, partially or totally, suppressed by appropriate design of the inlet hole curvature and non-cylindrical injection hole Abstract The flow inside a purpose built enlarged singleorifice nozzle replica is quantified using time-averaged X-ray micro-computed tomography (micro-CT) and highspeed shadowgraphy. Results have been obtained at Reynolds and cavitation numbers similar to those of real-size injectors. Good agreement for the cavitation extent inside the orifice is found between the micro-CT and the corresponding temporal mean 2D cavitation image, as captured by the high-speed camera. However, the internal 3D structure of the developing cavitation cloud reveals a hollow vapour cloud ring formed at the hole entrance and extending only at the lower part of the hole due to the asymmetric flow entry. Moreover, the cavitation volume fraction exhibits a significant gradient along the orifice volume. The cavitation number and the needle valve lift seem to be the most influential operating parameters, while the Reynolds number seems to have only small effect for the range of values tested. Overall, the study demonstrates that use of micro-CT can ...

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“…The γ-ray densitometer has been used previously to measure porosities of fluidized beds (Grohse, 1955;Gidaspow, et al 1983). This technique is based on the fact that the reading of the transmitted γ-rays can be described as a linear function of the porosity of the system.…”

Section: Volume Fractions Determinationmentioning

confidence: 99%

University/NETL Student Partnership Program

Holder¹

2003

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2 methane on the coal surfaces that may otherwise stay adsorbed in the coal matrix by decreasing the partial pressure of methane in the gas mixture. In addition, experimental work conducted on enhanced coalbed methane recovery by CO 2 injection [Reznik et al, 1984] shows that CO 2 is more adsorbing on coal than methane thereby giving it the potential to efficiently displace CBM and remain sequestered in the coal-seam. Thus coal-seams are considered to offer a very attractive option for CO 2 sequestration.In this work, focus is on the final part of the sequestration process -storage. The effects of various coal properties as well as operational scenarios on the injection and storage of CO 2 into a given coal-seam are analyzed. The analyses are based on results obtained from PSU-COALCOMP, a compositional coalbed methane numerical reservoir simulator capable of modeling the primary and enhanced recovery of coalbed methane.The operational design parameters considered in this study include the type, length and orientation of the injectors/producers while the coal-seam properties studied include coal porosity, coal permeability, cleat spacing, sorption capacity, and the initial conditions of the coal-seam -the reservoir pressure, adsorbed gas composition, amount of CO 2 initially adsorbed, water saturation and free-gas composition.Based on the data, results and analyses obtained, a CO 2 sequestration performance predictor tool is developed using artificial neural network (ANN) technology. The developed network will be able to predict the values of the performance indicators of the CO 2 sequestration process for a wide range of coal-seams and various production schemes. The developed ANN would also enhance our understanding of CO 2 sequestration process. 3 CHAPTER 2 LITERATURE REVIEW Carbon Dioxide SequestrationThe amount of carbon dioxide (CO 2 ) in the atmosphere has risen from preindustrial levels and most of this increase has been in recent years as shown in the data presented graphically in Figure 2-1. The corresponding increase in temperature as CO 2 levels increase raises environmental concerns such as global warming and its effects.This increase in CO 2 levels is attributed widely to the burning of fossil fuels, and if current trends in resource utilization continue, anthropogenic CO 2 emissions will increase rapidly during the 21 st century. Figure 2-2 shows the sharp increase in global CO 2 emissions over the last 100 years.The term "CO 2 sequestration" refers to the removal of CO 2 from either manmade emissions or the atmosphere and the safe, essentially permanent storage of this CO 2 .There are two main types of sequestration: direct sequestration, where CO 2 is removed from energy systems, and indirect sequestration, where CO 2 is removed from the ambient atmosphe re by enhanced natural processes. Sequestration is one of the three options for stabilizing CO 2 concentrations in the atmosphere and until the late 1990's, was not yet in the scientific lexicon. It is less familiar to the public at large than...

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Analysis of gas‐fluidized solid systems by x‐ray absorption

Cited by 68 publications

References 6 publications

The Effect of Particle Size on the Properties of Gas-Fluidized Beds

The Effect of Particle Size on the Properties of Gas-Fluidized Beds

Application of X-ray micro-computed tomography on high-speed cavitating diesel fuel flows

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