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 61 for “"Gas bubbles"”.
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Modelling the flow behaviour of gas bubbles in a bubble column
… framework that does predict the flow of multiple bubbles in the whole column. The non-linear Navier-Stokes (NVS) equations are used to model fluid flow around the bubble. This study focusses on the Reynolds number range where the linear Stokes equations can be used to accurately predict the flow …
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Measurement of gas bubbles in a vertical water column using optical tomography.
… to a tomographic imaging system for use with gas/water mixtures. Several sensing techniques for measurement of two component flow using non-intrusive techniques are discussed and their relevance to tomographic applications considered. Optical systems are shown to be worthy of investigation. …
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Numerical Simulations of Interactions of Solid Particles and Deformable Gas Bubbles in Viscous Liquids
… interactions of solid particles and deformable gas<br />bubbles in viscous liquids is very important in many applications,<br />especially in mining and chemical industries. These interactions<br />involve liquid-solid-air multiphase flows and an<br />arbitrary-Lagrangian-Eulerican (ALE) …
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Heat Transfer From a Liquid to Gas Bubbles During Formation and Translation of the Bubbles Through the Liquid.
… amount of heat transfer does occur when gas bubbles form and translate through a relatively warm liquid. Therefore, a more detailed experiment was conducted to investigate this heat-transfer phenomenon.A heat exchanger was constructed which used warm tap water as the liquid and cool …
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Mass transfer from spherical gas bubbles and liquid droplets moving through power-law fluids in the laminar flow regime
"Continuous phase mass transfer coefficients are presented for internally circulating spheres of a Newtonian fluid traveling through a power-law type continuous phase in to so-called creeping-flow region. The Nakano and Tien stream functions allow the Sherwood number to be determined as a function …
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A study of the removal of metal ions from aqueous solution by adsorptive bubble separation methods
… and their subsequent flotation by small gas bUbbles' which are produced by the release, under shear, of pressurized air-saturated water into the solution at atmospheric pressure. Optimum conditions for the removal of copper (II) and zinc (II) in the concentration range 10.0 ppm to 50.0 …
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Bubble dynamics in polymeric foams
… of fluid viscoelasticity on the expansion of gas bubbles in polymer foams for both non-reactive and reactive polymers are investigated. Polymer foams are used extensively in consumer products, from car parts to upholstery. They are produced either by injection moulding (of non-reactive …
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Determination of UO2 thin films mechanical properties under heavy ion irradiation using nanoindentation and finite element modeling
… were deposited on YSZ substrates using reactive-gas magnetron sputtering. Nanoindentation was used to measure the mechanical properties of the as-grown and irradiated films. Finite element modeling was used to account for the substrate effect on the measurements. Two sets of experiments were …
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Physicochemical Interactions at Interfaces: Mass and Charge Transfer at Chemically Reacting Interfaces
… the impacts that microscale texture have for gas evolving electrochemical electrodes is investigated to highlight the unique design considerations that exist for gas evolving electrochemical electrodes that are distinctly different than non-gas evolving electrochemical systems. Next, the …
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Use of computational fluid dynamics in the design of bubble column reactors
… that depict the transport of discrete phases (gas bubbles or solid particles) and model biochemical reactions in a bubble column reactor are discussed here. The mixture model was used to calculate gas-liquid, solid-liquid and gasliquid-solid interactions. Multiphase flow is a difficult …
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Cavitation methods in therapeutic ultrasound : techniques, mechanisms, and system design
… means, cavitation, the formation and collapse of gas bubbles, can occur. These bubbles can be unpredictable in their timing and location and often interfere with thermal therapies. Therefore, focused ultrasound techniques have tried to avoid bubbles and their effects. However, gas bubbles in vivo …
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Effects of Dissolved Gas Supersaturation and Bubble Formation on Water Treatment Plant Performance
Gas bubbles that form within water treatment plants can disrupt drinking water treatment processes. Bubbles may form whenever the total dissolved gas pressure exceeds the local solution pressure, a condition termed dissolved gas "supersaturation." This project investigated how bubble formation …
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Characterization of penicillin production by an immobilized biofilm of Penicillium chrysogenum
… oriented so that the liquid media and sparged gas bubbles flow uniformly over the two slab faces. The conditions necessary for definite oxygen and sugar limitations were found by operating under various bulk nutrient concentrations. The periodic determination of total biofilm volume (rate of …
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Multiphase flows in polymer microfluidic systems
… of surfactants and operating conditions. For gas-liquid two-phase flow, dry air and deionized water were driven into hot embossed PMMA microchannels with 200 μm square test microchannels. Flow regimes, flow maps and the lengths of the gas bubbles and liquid plugs in terms of the liquid …
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Oxidation kinetics of molten copper sulphide
… measurements and qualitative observations. Off-gas analyses for SO2 and 02 were conducted to determine the oxidation rates of approximately 200-gram samples, ofmolten 99.5% Cu2S. The molten sulphide was held in alumina crucibles (approximately 44 mm diameter and 75 mm height), and top-lanced …
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Atomistic Simulation Of Plasma Interaction With Plasma Facing Components In Fusion Reactors
… prior to deuterium cluster formation, and gas bubbles were observed. The formation of gas bubbles were caused by the near surface deuterium super-saturation region and the subsequent plastic deformation induced by the local high gas pressure.</p> <p>Tungsten irradiated by carbon and …
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Numerical modeling of multiphase fluid flow through the electrolytic cell
… (NaCl + H2O → NaOCl + H2) produces hydrogen gas bubbles near the cathode's surface inside a continuous liquid phase. In time, solid particles of calcium carbonate appear on the cell's anode due to the cell operation. Thus, the fluid flow process in the cell, in general, is a three-phase …
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A transmission electron microscopy study of inert gases in silicon and iron
This thesis presents a study of inert gas inclusion in iron and silicon, as a result of ionimplantation. The effect of ion implantation conditions on the formation anddevelopment of inert gas bubbles within these solids has been explored, and the mobilityof these nanoscale bubbles during heating …
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Sonoelectrochemical (20 khz) production of hydrogen from aqueous solutions
… any electrolytic system and mechanically removes gas bubbles on the electrode surface. This work takes this previous research further by quantifying actual hydrogen gas output. The hydrogen evolution reaction was then directly compared with that calculated using the Ideal Gas Equation to quantify …
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Predispersed solvent extraction
… flotation of the aphrons on specially prepared gas bubbles, which are somewhat larger than aphrons and are called colloidal gas aphrons (CGA). Copper, uranium and chromium ions, and alizarin yellow were extracted from very dilute aqueous solutions using PDSE. Tests were performed in a vertical …
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