Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 30 for “"Gas Holdup"”.
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Gas holdup in a gas-liquid-fiber semi-batch bubble column
… connected to one of three perforated plate gas distributors with open area ratios A = 0.57%, 0.99%, and 2.14% is employed to study gas holdup and flow regime in Rayon and Nylon fiber suspensions. This study determines the effect of superficial gas velocity, fiber type, fiber mass fraction, …
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Hydrodynamics and gas holdup in a cocurrent air-water-fiber bubble column
<p>Gas-liquid-fiber flows are widely found in various unit operations in the pulp and paper industry and similar flow conditions may be found in other industrials, such as wastewater treatment, food processing, biological organism production, and pharmaceutical manufacturing;Flocculated fiber …
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The Effect of Operating Conditions on Gas Holdup and Mixing in Tower Fermenters
… conditions applicable to fermentation processes. Gas holdup was investigated thoroughly under different operating conditions in air-water systems. A number of fermentation media were also used as the liquid phase. It was found that apart from superficial gas velocity which is the governing factor …
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The effects of low aspect ratio and heat exchanging internals on the bubble properties and flow regime in a pilot-plant bubble/slurry bubble column for Fischer-Tropsch synthesis
… (F-T) is a process utilized to convert the syngas mixture of CO and H<sub>2</sub> to synthetic fuel and chemicals that executed commercially by using the bubble/slurry bubble column reactor. The experimental results reveal that the investigated parameters, in terms the presence of internals, …
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Numerical Modeling of Air-Water Flows in Bubble Columns and Airlift Reactors
… by varying the column diameter and the inlet gas velocity using two-dimensional simulations. The typical characteristics of a homogeneous, slug, and heterogeneous flow were shown by examining gas holdup. The flow field predicted using two-dimensional simulations of the airlift reactor showed a …
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Mass transfer in bubble column contractors
Gas holdup and overall volumetric mass transfer coefficients in bubble column contactors have been investigated for water and aqueous electrolyte solutions. Two methods were used to obtain experimental data on volumetric mass transfer coefficients: the steady state oxidation technique and a …
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Viscous liquids in bubble columns
… studied in an 8.8cm diameter column, and the gas holdup, resulting from continuous bubbling of gas into this column, was also measured. Agreement between holdup predicted by the equation of Nicklin et al (1962), and experimental data in the present work and that of other workers is good. The …
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CFD simulation of the dynamic flow behavior in a bubble column reactor
… to predict the bubbly flow parameter such as gas holdup, contact surface area, air volume fraction, pressure drop, and velocity magnitude to understanding the hydrodynamic flow behaviors. Three types of gas distributor design are tested on the 1.5 m height and 0.15 m diameter bubble column …
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Heat transfer and bubble dynamics in bubble and slurry bubble columns with internals for Fischer-Tropsch synthesis of clean alternative fuels and chemicals
"Synthesis gas, a mixture of CO and H₂ obtained from coal, natural gas and biomass are increasingly becoming reliable sources of clean synthetic fuels and chemicals and via Fischer-Tropsch (F-T) synthesis process. Slurry bubble column reactor is the reactor of choice for the commercialization of …
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Biological Aerated Filters: Oxygen Transfer and Possible Biological Enhancement
… were initially determined over a wide range of gas and liquid flow rates without the presence of bacteria. The mass-transfer coefficients (KLa(T)) were measured using a nitrogen gas stripping method and were found to increase as both gas and liquid superficial velocities increase, with values …
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Process intensification for the iron-catalysed slurry-phase Fischer-Tropsch Reactor System
… publication, this requires operation at higher gas velocity, higher catalyst concentration and at higher temperature and/or pressure. The closest prior art proposal was published by Van der Laan et al. (1999) and a target was set to improve the reactor productivity by at least 50 %, relative to …
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Visualizing fluidized beds with X-rays
… of flow conditions. 3-D local, time-averaged gas holdup is calculated from CT data, while dynamic features are captured by X-ray stereography. The results show that CT is most effective on glass bead fluidized beds. Due to high X-ray attenuation, glass bead CT data has higher resolution than …
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Oxygen Mass-Transfer in Tower Fermenters
… of unsteady-state experiments. The effects of gas flow-rate, nutrient concentration, antifoams and microbial concentration on mass—transfer have been studied in detail: superficial air velocity and the presence of anti-foams are shown to be the most important factors. Measurements with the …
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Fluid Dynamics And Scale-Up Of Bubble Columns With Internals
… of the phenomena associated with the local gas holdup and the bubble dynamics: specific interfacial area, frequency, velocity, and chord length) and their radial profiles via detailed experimentations by means of the four-point optical fiber probe as a measuring technique. In addition, the …
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Analysis of the thermal hydraulics of a multiphase oxygen production reactor in the Cu-Cl cycle
… water splitting process by Cu-Cl cycle, oxygen gas is produced by an endothermic thermolysis process in a three-phase reactor. In this thesis, the required heat for the thermolysis process is provided by adopting the idea of heating some of the stoichiometric oxygen gas by using a nuclear …
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Hydrodynamic Characterization of 3D Fluidized Beds Using Noninvasive Techniques
… rates occur through the action of vertical gas injection into a column of solid particles. Although these properties give fluidized beds great advantages over other processing systems, the hydrodynamic characterization of fluidized beds is important for the efficient processing of many …
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Scaleup and hydrodynamics study of gas-solid spouted beds
… understanding of the complex flow structure of gas-solid spouted bed is crucial for design, scale-up and performance. Advanced gas-solid optical probes were developed and used to evaluate different hydrodynamic parameters of spouted beds. These optical probes measure solids concentration, …
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Scale-up investigation and hydrodynamics study of gas-solid fluidized bed reactor using advanced non-invasive measurement techniques
… methodology for hydrodynamics similarity of gas-solid fluidized bed reactors (FBRs) by implementing our advanced non-invasive measurement techniques which are gamma ray computed tomography (CT) and radioactive particle tracking (RPT) that measure local hydrodynamic parameters. Experiments …
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Evaluating of scale-up methodologies of gas-solid spouted beds for coating triso nuclear fuel particles using advanced measurement techniques
… to evaluate the scale-up methodology of gas-solid spouted beds for hydrodynamics similarity that has been reported in the literature based on matching dimensionless groups and the new mechanistic scale up methodology that has been developed in our laboratory based on matching the radial …
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Application of oxygen microbubbles for groundwater oxygenation to enhance biodegradation of hydrocarbons in soil systems
… Also, after injection of microbubbles gas retentions over 70 percent were achieved. Oxygen Transfer Coefficients, KLa(s), were higher in layered soil in VSTC compared to non-layered soil when the same amounts of microbubbles were injected in the cell. The effect of cell layering, …
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