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Showing 1 to 20 of 22 for “"Subcooled Flow"”.
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An Investigatio of Subcooled flow Boiling with Emphasis o nits Initiation
Made available in DSpace on 2017-07-06T18:55:40Z (GMT). No. of bitstreams: 2 Nourmohammadi_Khosrow_MS.pdf: 44965532 bytes, checksum: e061f1448c007bf887afc3534ab2da4a (MD5) license.txt: 4813 bytes, checksum: 715c4321821a960fa1a1e91d2ac7ebce (MD5) Previous issue date: 1980
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Bubble behavior in subcooled flow boiling on surfaces of variable wettability
Flow boiling is important in energy conversion and thermal management due to its potential for very high heat fluxes. By improving understanding of the conditions leading to bubble departure, surfaces can be designed that increase heat transfer coefficients in flow boiling. Bubbles were visualized …
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Experimental study of heat flux partitioning in pressurized subcooled flow boiling
Understanding of subcooled flow boiling and the critical heat flux (CHF) is of the utmost importance for both safety and profitability of pressurized water nuclear reactors since they are major factors in the determination of the reactor power rating. Motivated by the emergence of a new wall …
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Synthesis of CRUD and its effects on pool and subcooled flow boiling
… (Chalk River Unidentified Deposits) on pool and subcooled flow boiling parameters. Previous pool boiling studies have demonstrated the potential of porous, hydrophilic surfaces to lead to more efficient boiling. CRUD is a naturally occurring porous, hydrophilic layer that forms on fuel rods …
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Experimental study on subcooled flow boiling on heating surfaces with different thermal conductivities
Subcooled flow boiling is generally characterized by high heat transfer capacity and low wall superheat, which is essential for cooling applications requiring high heat transfer rate, such as nuclear reactors and fossil boilers. In this study, subcooled flow boiling on copper and stainless steel …
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Investigation of Separate Effects of Surface Condition on Subcooled Flow Boiling Heat Transfer
… 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 boiling crisis and predicting the CHF limit is key to the safety and …
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An Experimental Study of Subcooled Flow Boiling at Elevated Pressure in an Annular Flow Channel
… setup was developed to study the region of subcooled flow boiling. Multiple studies were carried out to investigate the effects of liquid velocity, pressure, and temperature on the boiling heat transfer of subcooled fluid flowing through a heated annular channel. Water was used as the …
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Experimental Investigation of Subcooled Flow Boiling and CHF at Prototypical Pressures of Light Water Reactors
… crisis combined with accurate models of nucleate flow boiling heat transfer. High-resolution, in situ experiments performed at prototypical pressures of light water reactors (LWRs) are needed in order to elucidate the phenomenon of the boiling crisis and to inform the development of boiling models …
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Subcooled flow boiling heat transfer and critical heat flux in water-based nanofluids at low pressure
… 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 diamond nanoparticles in water (< 0.1 % by volume) at atmospheric pressure. It was found that for comparable test conditions …
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Development and assessment of a physics-based model for subcooled flow boiling with application to CFD
… provides an enhanced physical description of flow boiling.
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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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The effects of orientation angle, subcooling, heat flux, mass flux, and pressure on bubble growth and detachment in subcooled flow boiling
… 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, orientation angles of 0' (downward-facing horizontal), 30°, 45°, 60°, …
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Water evaporation in vertical tubes: an analytical approach for the subcooled flow boiling region and development of a method for evaluation and sizing evaporators = Evaporación de agua en tubos verticales: análisis de la región de ebullición subenfriada y desarrollo de un método de evaluación y Dimensionado de evaporadores
… of water evaporation for convective upward flows in vertical tubes, used in industrial applications. Both, the heat transfer process and the pressure drop mechanism, are considered. However, special attention has been put on the heat transfer process in the transition from pure liquid to …
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Infrared Thermometry Analysis of Surface Effects in Subcooled and Saturated Boiling of Water
In this work, the dynamics of subcooled and saturated flow boiling are studied, focusing on the influence of surface characteristics, visualized through advanced diagnostics capturing micro-scale phenomena. Utilizing specially crafted thin-film infrared heaters, we measured bubble dynamics …
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Advancing State-of-the-art Multiphase CFD Modeling for PWR Applications
… represent the relevant physical phenomena in flow boiling. However, the still incomplete understanding of the ability of these closures to accurately capture the underlying physics limits the adoption of M-CFD in reactor development and design optimization. Due to the interaction of complex …
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Development of a general purpose subgrid wall boiling model from improved physical understanding for use in computational fluid dynamics
… capabilities were developed for application to subcooled flow boiling through this work. The target was to introduce, and demonstrate, all necessary mechanisms required to accurately predict the temperature and heat flux for subcooled flow boiling in CFD simulations. The model was developed …
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Geometric and numerical optimisation of single- and two-phase convective heat transfer in microchannel heat sinks
… square microchannels (micro passages for liquid flow in the heat sinks) were studied to enable electronic chip manufacturers to produce more powerful and durable integrated circuits at temperatures well below the recommended highest operating temperature. There is the need to optimise different …
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Experimental Investigation of Critical Heat Flux Enhancement on Engineered Surfaces with Infrared Thermometry
… light on the phenomena involved in the pool and subcooled flow boiling of water on these surfaces, including above-atmospheric pressure conditions (4 bar). We show that the presence of an intra-pillar liquid layer is the primary reason for CHF enhancement on surfaces with engineered micro-pillars …
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Modeling and simulation of liquid microlayer formation and evaporation in nucleate boiling using computational fluid dynamics
… heat fluxes. In Pressurized Water Reactors (PWR) subcooled flow boiling can occur in hot sub-channels. As a bubble grows outside of a surface imperfection during nucleate boiling, viscous stresses at the wall can be strong enough to impede liquid motion and trap a thin liquid layer - referred to …
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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
… 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 of the liquid motion to the heat …
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