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 27 for “"bubble diameter"”.
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Bubble Dynamics and Dense Phase Composition in 2-D Binary Gas-Solid Fluidized Bed
… (2D) fluidized bed was used to study bubble dynamics and dense phase composition distribution in order to gain some fundamental understanding of this system. Digital image analysis (DIA) was employed to measure bubble diameter, bubble rise velocity, bed expansion and particle …
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The development of frother optimisation techniques in full scale flotation plants
… scale plant using the Anglo American Platinum Bubble Sizer (AAPBS) which is a commonly used tool by the plant metallurgist. The techniques developed have been based on the application of fundamental research of frothers in literature. This thesis consists of three main focus areas: 1) …
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Computational Modeling and Simulations of Hydrodynamics for Air-Water External Loop Airlift Reactors
… investigated. The gas-liquid flow dynamics in a bubble column were simulated using a FORTRAN code developed by Los Alamos National Laboratory, CFDLib, which employs an Eulerian-Eulerian ensemble averaged method. A two-dimensional Cartesian coordinate system was used to conduct an extensive grid …
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Experimental investigation of local properties in two-phase fluid-flow hydrodynamics
… of gas void fraction, gas velocity, gas bubble diameter, and bubble passage frequency were made in a concurrent-flow, vertical rectangular channel (15.0 x 1.25 cm) having an aspect ratio of 12:1. Twenty (20) flows were analyzed with superficial gas and liquid velocities ranging from 0.04 …
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Biofilm Removal Using Bubbles and Sound
… It has been found that the passage of a bubble across a surface to which bacteria has adhered can remove the bacteria from the surface. Biofilms of Streptococcus mutans were grown on glass coverslips as a simple model for oral plaque. The coverslips were mounted in a Plexiglas chamber …
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A Numerical Study of the Flow and Heat Transfer in the Near Field of a Cylindrical Bubble Moving in a Narrow Channel
… simulation is performed of a cylindrical bubble moving in a pressure-driven flow of Novec-649 in a heated channel. The upper wall is an electrically heated metal foil, and the bubble diameter is on the order of the channel spacing. Phase change is not included to isolate the contribution …
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Generating Gaseous Emboli Mimics in an ECMO Flow Phantom
… masses of solid blood clots and gaseous air bubbles have the potential to occlude blood vessels and lead to complications such as neurological damage. Existing ultrasound methods for detecting and characterizing them are designed and tested on data sets that often are small, are not …
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Characterization and scale-up of microbubble generation in column flotation
… hydrodynamic studies suggest that small air bubbles can be used to improve the performance of column flotation. Tests carried out at Virginia Tech during the past several years have shown that various types of inline motionless (or static) mixers can successfully produce microbubbles for …
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Design and Testing of a Bubble Generator for Molten Salt Surrogate Fluid
… explores the design, testing, and modeling of a bubble injector intended for use in studying bubble dynamics in molten salt reactors using a room temperature surrogate fluid by matching the Reynolds number, Eötvös number, and Morton number defined by the properties of the helium bubbles in the …
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Bubble scavenging in Hele-Shaw cell
When a bubble rises in a suspension of microscopic particles, the particles that collide with the bubble can stick to it and be brought to the surface, a process used to separate microparticles in a variety of industrial processes ranging from wastewater recovery to mineral flotation. Previous …
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Measurement of near-surface void fraction and macrolayer thickness in boiling water and silica-based nanofluid
… have an error of 11.9% and 10.4% for measuring bubble diameter in water and R-123, respectively, and an error of 5.2% and 7.1% for measuring velocity in water and R-123. The macrolayer dryout theory of CHF was tested by investigating the change in macrolayer thickness for different heat fluxes …
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Numerical Analysis of Multiphase Flow in Bubble Columns and Applications for Microbial Fuel Cells
… predict the hydrodynamics of a column reactor. Bubble columns have applications across many engineering disciplines and improved modeling techniques help to increase the accuracy of numerical predictions. An Eulerian-Eulerian multi-fluid model was used to simulate fluidization and to capture the …
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Modelling and simulation of all-vanadium redox flow batteries
… then incorporated into the modelling frame work. Bubble formation as a result of evolution at the negative/positive electrode is included in the model, taking into account the attendant reduction in the liquid volume and the transfer of momentum between the gas and liquid phases, using a modified …
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Development of a multi-stage bubble column dehumidifier for application in a hymidification dehumidification desalination system
… rates. The proposed solution is to create a bubble column for improved condensation. The condensing coil will be submerged in a body of water while humid air is sent through a sieve plate to create bubbles in this body of water where it will condense directly. Firstly, a single stage bubble …
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Experimental study of flow boiling under subatmospheric pressures in a vertical square channel
… Boiling number, Jakob number, and density ratio. Bubble departure diameters and departure frequencies are measured via high-speed photography and compared to existing models. CHF data are presented as a parametric study of pressure from 20 kPa to 108 kPa, mass flux from 45 kg/m2s to 190 kg/m2s, …
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Integrated Liquid/Steam Multiphase Flow Sensors for Geothermal Applications
… optic sensors will be externally mounted to a bubble column along with a digital camera. Data collected from both methods such as bubble diameter, velocity, and volume (air percentage) will be compared. The camera serves as a rudimentary calibration method. Three flow conditions are chosen for …
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LARGE-EDDY SIMULATION OF DEEP-WATER HYDROCARBON PLUME DYNAMICS
… and hydration process that weakens the bubble-induced buoyancy for driving the plume. In this study, a new modeling strategy is developed to efficiently incorporate the gas dissolution and hydration effects into a fast Eulerian-Eulerian large-eddy simulation (LES) model. By …
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Solids mixing and segregation in a gas spout-fluid bed-effect of the distributor design
… fluidised bed and of variation of the gas inlet diameter in a spouted bed were also briefly investigated for purpose of comparison. Large particles were selected for study because they are becoming increasingly important in industrial fluidised beds but have not been thoroughly investigated. The …
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The effect of gas on multi-stage mixed-flow centrifugal pumps
… literature shows that the size of the gas bubbles present in the fluid is critical to the pump performance. A transparent, full-scale pump was built in order to explore the flow features in single and multiphase flows. Laser Doppler Velocimetry and high speed imaging in single phase flow …
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The Physical Mechanism of Blood-Brain Barrier Opening Using Focused Ultrasound and Microbubbles
… ultrasound (FUS) in conjunction with microbubbles. The physical mechanism behind the opening, however, has not been identified. Insight into the mechanism can be critical for delineating the safety profile for in both small and large animals alike. Therefore the purpose of this dissertation …
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