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 18 of 18 for “"Flow boiling heat transfer"”.
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Investigation of Separate Effects of Surface Condition on Subcooled Flow Boiling Heat Transfer
In Pressurized Water Reactor (PWRs), heat generated by nuclear fissions is effectively transferred to the water coolant by subcooled flow boiling. The maximum reactor power is limited by the critical heat flux (CHF), at which the boiling crisis occurs. Understanding the mechanisms that trigger this …
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Enhanced flow boiling heat transfer in microchannels with structured surfaces at varied mass flow rates
This thesis investigates the role of mass flux on flow boiling heat transfer in microchannels with surface micropillar arrays. The motivation for this investigation was to determine the general trends of the optimal micropillar array geometry in terms of its heat transfer capabilities. The …
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Subcooled flow boiling heat transfer and critical heat flux in water-based nanofluids at low pressure
… in water, or other base fluids. Previous pool boiling studies have shown that nanofluids can improve the critical heat flux (CHF) by as much as 200%. In this study, subcooled flow boiling heat transfer and CHF experiments were performed with low concentrations of alumina, zinc oxide, and …
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Carbon Dioxide and R410A Flow Boiling Heat Transfer, Pressure Drop, and Flow Pattern in Horizontal Tubes at Low Temperatures
… and refrigeration systems. In this study, CO2 flow boiling heat transfer coefficients and pressure drop are measured in macro-scale (6.1 and 3.5 mm) tubes at evaporation temperatures of -15 and -30°C. The measured results show that the nucleate boiling is a main heat transfer mechanism in …
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Exploring the fundamental mechanisms of refrigerant flow boiling heat transfer enhancement on scalable micro- and nanostructured metal surfaces through the state-of-the-art borecopy method
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2025-05-01
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Boiling Heat Transfer of Freon-113 Flowing Normal to a Tube: Effect of Tube Diameter
The effect of heater diameter on the pool and flow boiling heat transfer of saturated Freon-113 was examined. The heaters were horizontal copper tubes of diameter 1.59 to 7.94 mm (pool) and 3.18 to 12.7 mm (flow), heated internally by condensing steam. The test fluid, at atmospheric pressure, …
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Investigation of heat transfer in metal-foam tubes
… attract increasing attention in making compact heat exchangers due to its advanced thermal properties. In this project, the performance of forced convection and flow boiling heat transfer in metal-foam tubes has been investigated experimentally and theoretically. Compared to those of plain …
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Flow boiling of R134a in vertical mini-diameter tubes
… term experimental project devoted to investigate flow boiling heat transfer, pressure drop and flow visualization of R134a in small to mini/micro-diameter tubes. The experimental facility was first designed and constructed by X. Huo (2005) with the contribution of L. Chen (2006). In the present …
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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
The effects of orientation angle, subcooling, heat flux, mass flux, and pressure on bubble growth and detachment in subcooled flow boiling were studied using a high-speed video camera in conjunction with a two-phase flow loop that can accommodate a wide range of flow conditions. Specifically, …
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Experimental investigation of subcooled flow boiling using synchronized high speed video, infrared thermography, and particle image velocimetry
Subcooled flow boiling of water was experimentally investigated using high-speed video (HSV), infrared (IR) thermography, and particle image velocimetry (PIV) to generate a unique database of synchronized data. HSV allowed measurement of the bubble departure diameter. IR thermography allowed …
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Experimental Investigation of Subcooled Flow Boiling and CHF at Prototypical Pressures of Light Water Reactors
Boiling crisis is an important phenomenon that affects the performance and safety of pressurized water reactors (PWRs). Accurate predictions of the boiling crisis are difficult to make because they require a clear understanding of the physical mechanisms leading to the boiling crisis combined with …
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Experimental, theoretical and computational modeling of flow boiling, flow condensation and evaporating falling films
… In this study, phase change methods like flow boiling, flow condensation and evaporative falling-films are investigated experimentally, theoretically and computationally.</p> <p>The experimental part of the study consists of an investigation of the influence of inlet subcooling and …
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Prediction and mitigation strategies for the transient thermal performance of low thermal resistance microchannel evaporators
Microchannel flow boiling heat transfer offers an effective thermal management solution for high heat flux microelectronic devices such as laser diodes. The high heat transfer rates, nearly isothermal flow conditions, high surface area-to-volume ratios, and lower required pumping powers facilitate …
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Investigation of the influence of gravitational body force effects on critical heat flux for flow boiling with subcooled and two-phase inlet
… Control Systems (TCSs) with ones that rely on flow boiling and condensation. This transition will require a thorough understanding of the influence of reduced gravity on flow boiling and condensation, and the development of predictive tools for both. The primary purpose of the present study is …
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Thermal Transport Across Nano Engineered Solid-Liquid Interfaces
… liquid molecules play a very crucial role in heat transfer from solid to liquid, especially when the system dimension shrinks to the nanoscale range. Behavior of these interfacial liquid molecules depends on the characteristics of the interface. All the interfaces have different …
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Flash gas bypass - a way to improve distribution of adiabatic two-phase refrigerant flow in headers of microchannel evaporators
… problem of distribution of two phase adiabatic flow in headers of parallel flow evaporators, of typically microchannel design. Three main issues that will be explored in this thesis are: 1) separation of vapor-liquid refrigerant immediately after an expansion device in a compact T-junction and …
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Effect of micro-fin geometry on flow and heat transfer during evaporation in round tubes
In order to understand the mechanism of heat transfer enhancement due to micro-fin geometry, this dissertation develops a novel approach to visualize the two-phase flow pattern in transparent micro-finned tubes under both adiabatic and diabatic conditions. Rather than the conventional sight-glass …