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 16 of 16 for “"Departure diameter"”.
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The effects of orientation angle, subcooling, heat flux, mass flux, and pressure on bubble growth and detachment in subcooled flow boiling
… of 20 microns) in the determination of bubble departure diameter. The data indicate that bubble departure diameter increases with increasing heat flux, decreasing mass flux, decreasing levels of subcooling, and decreasing pressure. Also, bubble departure diameter increases with decreasing …
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Wettability of candidate Accident Tolerant Fuel (ATF) cladding materials in LWR conditions
… determines nucleation site density, bubble departure diameter, and bubble departure frequency.
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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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Boiling on hierarchical nanoengineered surfaces
… transfer performance with focus on the bubble departure diameter and frequency. Ultrahigh critical heat fluxes (CHF) greater than 400 W/cm2 were obtained, corresponding to an enhancement of ≈245% compared to smooth copper surfaces. Our work reveals the existence of a linear relationship between …
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Synthesis of CRUD and its effects on pool and subcooled flow boiling
… heat flux (CHF), nucleation site density, bubble departure frequency, and bubble departure diameter. These heaters were tested in pool and flow boiling facilities in MIT's Reactor Hydraulics Laboratory. Synthetic CRUD was created using layer-by-layer deposition of 100 nm silica nanoparticles to …
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Comparison of water boiling models against recent experimental data, with special emphasis on the bubble ebullition cycle
… 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 proposed by M.Z. Podowski. In my …
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Investigation of the pool boiling heat transfer enhancement of nano-engineered fluids by means of high-speed infrared thermography
… nanoparticles to the working fluid. Bubble departure diameter and frequency, growth and wait times, and nucleation site density were measured for every nucleation site during nucleate pool boiling at multiple superheats. The data were compared with decades-old and poorly-validated models and …
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The coupled effect of surface roughness and nanoparticle size on the heat transfer enhancement of nanofluids for pool boiling
… for the SPIP, new correlations for bubble departure diameter and nucleation site density were implemented as a user-defined function in ANSYS Fluent. The bubble waiting time coefficient was corrected at different nucleation site density during validation study where good agreement was found …
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Experimental study of flow boiling under subatmospheric pressures in a vertical square channel
… 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, and inlet …
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Experimental study of heat flux partitioning in pressurized subcooled flow boiling
… growth and wait times, nucleation frequency, departure diameter as well as the partitioning of the wall heat flux. While established mechanistic models can capture the trends of growth time and wait time with relatively good accuracy, this work reveals current models do not accurately predict …
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Numerical study of vertical subcooled boiling flow with new wall nucleation models
… since wall nucleation parameters, such as bubble departure diameter and bubble departure frequency, partially constitute the boundary conditions of gas phase. However, in previous work, sensitivity study of wall nucleation models and validation of predicted wall nucleation parameters were not …
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Autonomous Experimentation to Accelerate Boiling Heat Transfer Research
… site density, bubble growth time, wait time, departure diameter, dry area fraction and distribution, and contact line density. To this end, a machine learning (ML) methodology was developed to accelerate the analysis of infrared data obtained during boiling heat transfer investigations. Deep …
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Experimental investigation of variability between nucleation sites in flow boiling
This Thesis was approved for publication on 2017-12-04 at 12:43.
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Enhancement of Nucleate Boiling on Rough and Dimpled Surfaces with Application to Composite Spreaders for Microprocessors Immersion Cooling
… the transient growth measurements, the bubble departure diameter and detachment frequency were determined, and used to estimate the surface average density of nucleation sites on the smooth and rough Cu surfaces. For the smooth Cu (Ra = 0.039 μm), the determined departure bubble diameter, Dd, …
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Effect of boiling on deposition of metallic colloids
… cavities is conducted. A bubble growth and departure dynamics model is developed for artificial active sites and is validated with the experimental data. The variation of bubble departure diameter with wall temperature is analyzed with experimental results and shows coherence with earlier …
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Effect of micro-fin geometry on flow and heat transfer during evaporation in round tubes
… tubes and smooth tubes with the inner diameter of 6.3 mm were conducted. The results showed that the average heat transfer enhancement factor of the axial micro-finned tube is 1.34 and the average pressure drop penalty factor is around 1.23. In the second part of this thesis, two-phase …