Design and Construction of a Subcooled Boiling Flow Loop with an Internally Heated Vertical Annulus for Use in Testing Departure from Nucleate Boiling (DNB) PDF Download
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Author: Joseph Kreynin Publisher: ISBN: Category : Languages : en Pages : 56
Book Description
The design and testing of an apparatus to use in subcooled boiling flow experiments. A vertical annulus flow loop was design to mimic a rod used in a reactor boiler. The system was tested at different velocities and temperatures to verify it could be used in a range of experiments to try and match real world conditions. The system managed to produce the desired outcome of bubble growth in a desired location as well as run with the PIV system showing good prospect in the intended use of the experimental set up.
Author: Joseph Kreynin Publisher: ISBN: Category : Languages : en Pages : 56
Book Description
The design and testing of an apparatus to use in subcooled boiling flow experiments. A vertical annulus flow loop was design to mimic a rod used in a reactor boiler. The system was tested at different velocities and temperatures to verify it could be used in a range of experiments to try and match real world conditions. The system managed to produce the desired outcome of bubble growth in a desired location as well as run with the PIV system showing good prospect in the intended use of the experimental set up.
Author: R. J. Weatherhead Publisher: ISBN: Category : Cooling Languages : en Pages : 40
Book Description
Experimental data obtained at CISE on two-phase adiabatic flow are presented. The measured quantities are pressure drop and liquid film thickness on the inner and the outer wall of the conduit. The pressure loss and film flow rate are evaluated. The experimental data are discussed and the effects of various physical and geometrical parameters are investigated. A simple relation for the pressure loss in adiabatic dispersed regime is given.
Author: Rosemary M. Sugrue Publisher: ISBN: Category : Languages : en Pages : 122
Book Description
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, orientation angles of 0' (downward-facing horizontal), 30°, 45°, 60°, and 90° (vertical); mass flux values of 250, 300, 350, and 400 kg/m2s, with corresponding Froude numbers in the range of 0.42 to 1.06; pressures of 101 (atmospheric), 202, and 505 kPa; two values of subcooling (10°C to 20°C); and two heat fluxes (0.05 to 0.10 MW/m2) were explored. The combination of the test section design, high-speed video camera, and LED lighting results in high accuracy (order 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 orientation angle, i.e. the largest bubbles are found to detach from a downward-facing horizontal surface. The mechanistic bubble departure model of Klausner et al. and its recent modification by Yun et al. were found to correctly predict all the observed parametric trends, but with large average errors and standard deviation: 35.7+/-24.3% for Klausner's and 16.6±11.6% for Yun's. Since the cube of the bubble departure diameter is used in subcooled flow boiling heat transfer models, such large errors are clearly unacceptable, and underscore the need for more accurate bubble departure diameter models to be used in CFD.
Author: G. H. Yeoh Publisher: ISBN: Category : Change of state (Physics) Languages : en Pages : 27
Book Description
An improved wall heat flux partitioning model at the heated surface was developed by Yeoh et al. This model, coupled with a three-dimensional two-fluid model and Multiple Size Group model, has led to satisfactory agreement being achieved between the model predictions and experimental measurements. Nevertheless, one shortcoming is the reliance on empirical correlations for the active nucleation site density in the wall heat flux partitioning model. This discrepancy brings about uncertainties, especially in appropriately evaluating the vapor generation rate, which greatly influences the model prediction on the axial and radial void fraction profiles within the bulk fluid flow. By considering the fractal model with the aforementioned subcooled boiling flow model in the absence of empirical correlations for the active nucleation site density, a comprehensive mechanistic model to predict vertically oriented subcooled boiling flows is developed. The proposed model is assessed against the experimental data of axial measurements of Zeitoun and Shoukri and the radial measurements of Yun et al. and Lee et al. for vertical subcooled boiling flows within annular channels. Improved model predictions are obtained when the model is compared against typically applied empirical correlations for active nucleation site density. Discussions on the agreement of other two-phase flow parameters are also presented.
Author: Francesco D'Auria Publisher: Woodhead Publishing ISBN: 0081006799 Category : Technology & Engineering Languages : en Pages : 1200
Book Description
Thermal Hydraulics of Water-Cooled Nuclear Reactors reviews flow and heat transfer phenomena in nuclear systems and examines the critical contribution of this analysis to nuclear technology development. With a strong focus on system thermal hydraulics (SYS TH), the book provides a detailed, yet approachable, presentation of current approaches to reactor thermal hydraulic analysis, also considering the importance of this discipline for the design and operation of safe and efficient water-cooled and moderated reactors. Part One presents the background to nuclear thermal hydraulics, starting with a historical perspective, defining key terms, and considering thermal hydraulics requirements in nuclear technology. Part Two addresses the principles of thermodynamics and relevant target phenomena in nuclear systems. Next, the book focuses on nuclear thermal hydraulics modeling, covering the key areas of heat transfer and pressure drops, then moving on to an introduction to SYS TH and computational fluid dynamics codes. The final part of the book reviews the application of thermal hydraulics in nuclear technology, with chapters on V&V and uncertainty in SYS TH codes, the BEPU approach, and applications to new reactor design, plant lifetime extension, and accident analysis. This book is a valuable resource for academics, graduate students, and professionals studying the thermal hydraulic analysis of nuclear power plants and using SYS TH to demonstrate their safety and acceptability. Contains a systematic and comprehensive review of current approaches to the thermal-hydraulic analysis of water-cooled and moderated nuclear reactors Clearly presents the relationship between system level (top-down analysis) and component level phenomenology (bottom-up analysis) Provides a strong focus on nuclear system thermal hydraulic (SYS TH) codes Presents detailed coverage of the applications of thermal-hydraulics to demonstrate the safety and acceptability of nuclear power plants
Author: Publisher: ISBN: Category : Languages : en Pages : 19
Book Description
When evaluating a heated flow passage for vulnerability to static flow excursions, special note should be taken of flow restrictions which might allow premature vapor generation. In this study, measurements of steady state pressure drop were made for the downward flow of water in a vertical annulus. The outer wall was uniformly heated to allow subcooled boiling. Minima in the pressure drop characteristics were compared for test sections with and without longitudinal spacer ribs. For a given power and inlet temperature, the minimum occurred at a higher flow rate in the ribbed test section. This is attributed to vapor generation at the ribs. The work cited in this document show how a restriction in a heated channel can produce vapor which would not be observed in the absence of the restriction. In the present study, the effect of a flow restriction on the tendency to flow excursion is explored by finding demand curves for a heated annulus in subcooled boiling flow. The annulus is heated from the outside, and alternately equipped with and without longitudinal spacer ribs. These ribs separate the heated and unheated walls; in pressing against the heated wall they provide a means for premature vapor production.
Author: Joseph Kreynin
Author: Joseph Kreynin
Author: Longcong Wang
Author: Altaf Hasan
Author: R. J. Weatherhead
Author: Rosemary M. Sugrue
Author: G. H. Yeoh
Author: Paul Wei-ming Ing
Author: Reiner Schmidt
Author: Francesco D'Auria
Author: