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 21 for “"Bubble Nucleation"”.
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Molecular Interfaces and Heterogeneous Bubble Nucleation From Heated Surfaces At Nanoscale
… liquid. Therefore, it is important to understand bubble formation, its onset, and behavior over time to advance thermal management applications utilizing nanoscale characteristics. This work aims to investigate bubble nucleation and growth on heated surfaces and understand heat transfer at …
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Bubble nucleation in finite-density gauge theory using the AdS/CFT correspondence
… of with a discussion about phase transitions and bubble nucleation. We then move on to talk about subjects such as quantum field theory, string theory and the anti de-Sitter/conformal field theory (AdS/CFT) correspondence. Lastly, we look at the rotating black brane solution and the results for …
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Coupling electrolysis and surface patterning to improve onset of nucleate boiling and bubble departure in pool boiling heat transfer
… combined effects of electrolytic activation of bubble nucleation (via the hydrogen evolution reaction, HER) and engineering gold thin-strip microstructures fabricated on silicon substrates. The central hypothesis is that electrochemically generated hydrogen bubbles near the heating surface can …
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Enhancement of nucleate boiling heat transfer by surface modification in a cold plate evaporator
… surface area and thus allow for more efficient bubble nucleation. Heat transfer coefficients were calculated with both baseline and modified cold plates for varied heat and mass flux loadings to compare how effective the nanostructures are at improving heat transfer. Longevity of the coating in …
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A New Dynamic Fluid Flow Method for Studying the Phase Changes of the Light/Heavy Crude Oil-Solvent Systems
… as long as the outlet pressure was above the bubble-point pressure of the light crude oil‒CO2 system. However, the pressure gradient was suddenly increased once the outlet pressure was below the bubble-point pressure because the light crude oil‒CO2 system changed from one liquid phase into …
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Comparison of water boiling models against recent experimental data, with special emphasis on the bubble ebullition cycle
… with state-of-the-art techniques, models for nucleation site density, bubble departure diameter, and nucleation frequency were compared against the acquired data. The particular focus of this work is on the ebullition cycle and associated bubble nucleation frequency, looking at the models …
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The fundamentals of two-phase flow in wet domestic central heating systems
… a number of experiments to investigate typical bubble sizes, volumetric void fractions, bubble distributions and nucleation and dissolution rates and (5) the correlation of the data gathered as part of the present study with existing bubble size, nucleation and dissolution prediction models. …
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Physicochernical mechanics of surfactant-enhanced boiling heat transfer
… are known to enhance boiling by changing the way bubbles nucleate on the surface, grow, and depart from the surface. This thesis provides a mechanistic understanding of surfactant enhanced boiling from molecular and macroscopic perspectives with theory and experiments. First, a statistical …
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Effects of surface parameters on boiling heat transfer phenomena
… destabilizes the vapor film via heterogeneous bubble nucleation, and the micro posts provides intermittent liquid-surface contacts; both mechanisms increase LFP. In the last part, separate effect of nanoporosity and surface roughness on pool boiling CHF of a well-wetting fluid, FC-72, was …
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Thermal Management Using Liquid-vapor Phase Change in Nanochannels
… fluxes up to ∼77 W/cm2 at temperatures below nucleation, thus highlighting the thermal management potential of the fabricated geometry. Next, the porous nanochannels device capable to dissipate high heat flux is employed to regulate the temperature of a commercial PV panel by numerically …
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Experimental investigation of subcooled flow boiling using synchronized high speed video, infrared thermography, and particle image velocimetry
… data. HSV allowed measurement of the bubble departure diameter. IR thermography allowed measurement of wall superheat (local distribution and surface-averaged values), heat transfer coefficient, nucleation site density, and bubble frequency. Particle image velocimetry allowed for the …
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Liquid manipulation using engineered carbon nanotube surfaces
… Via in situ infrared imaging, faster bubble nucleation and departure are observed on the nanoporous microstructures; the additional imbibed volume contributes to the liquid supply for vaporization and delays the boiling crisis. Further enhancement could be achieved by optimizing the …
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Enhanced Extended-Surfaces for Two-Phase Pump-Less Cooling Loops
… to provide a very high density of potential bubble nucleation sites. A coating of copper fine wire screen is bonded to an extended surface (fin). The coating thickness ranged from 0.21mm to 1.3mm. The porosity of the coatings is held constant at 0.43 and the pore hydraulic diameter of the …
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Microfluidic investigation of cyclic solvent injection: from reservoir-on-the-chip to large scale
… platforms, examining the mechanisms involved in bubble evolution. Based on the visualization studies conducted on the microfluidic systems, it was found that solvent type, pressure depletion rate, and reservoir characteristics had a significant influence on the extension of foamy oil flow. …
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Experimental and mathematical modeling of foamy-oil evolution and flow in the primary production and CO₂-based cyclic solvent injection
… than that in the bulk fluids. In addition, the nucleation of CH4 bubbles was found to be more instantaneous than that of CO2/C3H8 bubbles. Numerically, a robust kinetic reaction model in the commercial CMG-STARS module was utilized to simulate the solvent exsolution and liberation processes in …
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Phase transitions in soft matter: From colloidal suspensions to biomolecular condensate regulation
… free energy differences can dictate the nucleation behaviour of these colloidal systems. Continuing with different colloidal systems, we investigate the crystallization of oppositely charged colloids, where multiple polymorphs compete in the nucleation and crystal growth stages. By …
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Linking Thermophysical Transitions and Rheological Properties to Polymer Foaming Outcomes with Carbon Dioxide
… and then impose a pressure reduction to initiate bubble nucleation and growth. The outcomes depend on the thermophysical and rheological properties of the polymer under the prevailing process conditions in the fluid. The present dissertation explores the high-pressure characterization and foaming …
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Scalable fabrication and characterization techniques of nano-engineered stainless-steel surfaces for boiling heat transfer
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-05-01
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Long-Pulsed Laser-Induced Cavitation: Laser-Fluid Coupling, Phase Transition, and Bubble Dynamics
… mechanism behind the formation of non-spherical bubbles induced by long-pulsed lasers. The proposed computational method accounts for the laser emission and absorption, phase transition, and the dynamics and thermodynamics of a two-phase fluid flow. In this new method, the model combines the …
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Production of Multi-layer and Cell-Containing Collagen Membranes Using Direct Electrophoretic Deposition
… from adhesion effects at the electrode and bubbles from electrolysis. A dialysed sacrificial layer of gelatin was used circumvent these issues and effects were tested for samples deposited at 30 V for 10 minutes. Dialysis decreased the conductivity of the gelatin and reduced the current …
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