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Wednesday, July 29, 2020 | History

3 edition of Dispersed flow film boiling found in the catalog.

Dispersed flow film boiling

Dispersed flow film boiling

an investigation of the possibility to improve the models implemented in the NRC computer codes for the reflooding phase of the LOCA

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  • 35 Currently reading

Published by Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, Available from Supt. of Docs., U.S. G.P.O., National Technical Information Service [distributor in Washington, DC, Springfield, VA .
Written in English

    Subjects:
  • Film boiling -- Computer simulation.,
  • Pressurized water reactors -- Loss of coolant -- Computer simulation.

  • Edition Notes

    Statementprepared by M. Andreani, G. Yadigaroglu.
    SeriesInternational agreement report -- NUREG/IA-0042.
    ContributionsYadigaroglu, George., U.S. Nuclear Regulatory Commission. Office of Nuclear Regulatory Research., Paul Scherrer Institut.
    The Physical Object
    FormatMicroform
    Paginationvii, 59 p.
    Number of Pages59
    ID Numbers
    Open LibraryOL14694274M

    book authored by Tryggvason, Scardovelli and Zaleski will be Flow boiling models for heat transfer in a boiling channel, including onset of nucleate boiling, subcooled Dispersed-Flow Film Boiling. Quenching. Multifield models(1 –) ee The need for multifield models. Data from two series of rod bundle heat transfer tests, low injection rate forced reflood tests, and droplet injection tests are presented in this paper to describe the effects of the spacer grids during dispersed flow film boiling.

    Download PDF: Sorry, we are unable to provide the full text but you may find it at the following location(s): (external link). Flow regime-dependent approximation for horizontal flow Flow-regime dependent two-phase correlations for inclined pipes Dispersed bubble flow Stratified flow Slug flow. 11 Flow regime determination The Beggs & Brill flow regime map The Taitel & Duckler horizontal flow model Flow regimes in vertical flow.

    Get this from a library! Dispersed flow film boiling: an investigation of the possibility to improve the models implemented in the NRC computer codes for the reflooding phase of the LOCA. [M Andreani; George Yadigaroglu; U.S. Nuclear Regulatory Commission. Office of Nuclear Regulatory Research.; Paul Scherrer Institut.]. Fan-Bill B Cheung, S. M. Bajorek and S. G. Srinivasan, , "Droplet-induced heat transfer augmentation downstream of a spacer grid during dispersed flow film boiling", Proceedings 8th International Topical Meeting on Nuclear Thermal Hydraulics, Operation and Safety (NUTHOS-8), .


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Dispersed flow film boiling Download PDF EPUB FB2

Dispersed Flow Film Boiling is the heat transfer regime that occurs at high void fractions in a heated channel. The way this heat transfer mode is modelled in the NRC computer codes (RELAP5 and TRAC) and the validity of the assumptions and empirical correlations used is discussed.

New data for dispersed flow film boiling of nitrogen are presented for Dispersed flow film boiling book following conditions: tube diameter, and in. ID; length 4 and 8 ft; mass veloc to 19, lb/hr ft 2; heat flux 0 to Btu/hr ft 2; inlet condition near saturation; exit quality 35 to previously presented analysis [12] is improved by accounting for droplet breakup due to Cited by: The dispersed flow film boiling heat transfer model of the COBRA-TF code has been modified by adding a small droplet field to the code as the fifth field.

The effect of smaller, thermally more active droplets on heat, mass and momentum transfer during DFFB has been modeled. A general correlation for heat transfer during dispersed flow film boiling is presented which is applicable to horizontal and vertical tubes.

It is based on the two-step model. It has been verified with data for 10 fluids in horizontal and vertical upflow. The fluids include refrigerants, hydrocarbons, cryogens, CO 2 and by: 4. Dispersed flow film boiling heat transfer in vertical narrow annular gaps with gap sizes ofand mm was experimentally investigated with de-ionized water as the working fluid at low mass velocities.

Comparisons of the experimental data with established correlations show that the correlations are not accurate for small by: 1. Dispersed Flow Film Boiling (DFFB) is characterized by important departures from thermal and velocity equilibrium that make it suitable for modeling with two-fluid models.

The fundamental limitations and difficulties imposed by the one-dimensional nature of these models are extensively discussed. The validity of the assumptions and empirical. A mechanistic droplet deposition model has been developed to quantify the direct contact heat transfer present in dispersed flow film boiling.

Lagrangian subscale trajectory calculations utilizing realistic velocity and temperature distributions in the momentum boundary layer are used to determine the number of dispersed droplets able to.

Dispersed flow consists of small liquid droplets entrained in a flowing vapor. This flow regime can occur in cryogenic equipment, in steam generators, and during nuclear reactor loss of coolant accidents.

A theoretical analysis of dispersed flow film boiling has been performed using mass, momentum and energy conservation equations for both phases.

Direct-Contact Heat Transfer Model for Dispersed-Flow Film Boiling Stephen M. Bajorek Kansas State University Department of Mechanical and Nuclear Engineering, Manhattan, Kansas & Michael Y.

Young Westinghouse Electric Company Nuclear Fuel Division. Dispersed flow film boiling is a regime of two phase heat trans-fer occurring in such applications as once-through steam generators, cryogenic machinery, and in the hypothetical loss-of-coolant accident (LOCA) in nuclear reactors.

It is characterized by a dispersion of liquid-phase droplets entrained in a continuous vapor-phase flow. A general correlation for heat transfer during film boiling in tubes is presented. It is based on the two-step model. It has been verified with data for nine fluids flowing up in tubes.

Dispersed-flow film boiling data were obtained in a large rod bundle (8 × 8) under steady-state and transient conditions with upward flowing high-pressure, high-temperature water.

The bundle is equipped with detailed thermometry, and has geometry typical of later generation pressurized water reactors with 17 × 17 fuel assemblies. NOTES ON TWO‐PHASE FLOW, BOILING HEAT TRANSFER, AND BOILING CRISES IN PWRs AND BWRs limited conditions (e.g.

dispersed bubbly flow, mist flow). In general, a significant slip between the two to film boiling. This sudden transition is called Departure from Nucleate Boiling (DNB), or.

Dispersed Flow Film Boiling > Film Boiling Correlations * Generally derived based on simplified experiments * Use beyond derivation space requires additional validation * Framatome has validated the application of these correlations In S-RELAP5 within the LBLOCA-space using data from a variety of testing programs, including.

A droplet model was used for the analysis of the fluid flow and heat transfer in the dispersed flow film boiling regime during reflooding of a tubular channel. Comparisons were made of the predicted wall heat fluxes, vapor temperatures, qualities, and droplet diameters and the experimental data.

The heat transfer predictions are in agreement with the data at locations away from the quench. @article{osti_, title = {Dispersed-flow film boiling in rod-bundle geometry: steady-state heat-transfer data and correlation comparisons. [PWR; BWR]}, author = {Yoder, G. and Morris, D. and Mullins, C.

and Ott, L. and Reed, D. A.}, abstractNote = {Assessment of six film boiling correlations and one single-phase vapor correlation has been made using data from 22 steady state. The void fraction is obtained from drift flux models.

For heat transfer calculations, the channel is divided into regions of single-phase-liquid heat transfer, nucleate boiling and forced-convection vaporization, inverted-annular film boiling, and dispersed-flow film boiling.

One of the significant features of established dispersed-flow film boiling is the existence of superheat in the vapor well below % equilibrium quality, and the presence of liquid droplets downstream of the % quality point [1–3].

It is clear that dispersed-flow film boiling is not a particularly efficient heat-transfer process. Annular flow is a flow regime of two-phase gas-liquid flow (see gas-liquid flow).

It is characterized by the presence of a liquid film flowing on the channel wall (in a round channel this film is annulus-shaped which gives the name to this type of flow) and with the gas flowing in the gas core. The flow core can contain entrained liquid droplets.

In the present work, a numerical model is developed to analyze the riser-downcomer system of a natural circulation steam generator. The design and operation of the riser-downcomer. The dispersed flow film boiling (DFFB) heat transfer regime is important to several applications including cryogenics, rocket engines, steam generators, and in the safety analysis of nuclear reactors.

Most notably, DFFB is responsible for the heat transfer during the blowdown and reflood portions of the postulated loss-of-coolant-accident (LOCA).“A General Correlation for Heat Transfer During Dispersed Flow Film Boiling in Vertical Tubes,” Proc. 14 th National Heat and Mass Transfer Conf., Kanpur, India, “A General Correlation for Heat Transfer During Dispersed Flow Film Boiling in Tubes,” .This report presents the latest results of an investigation of the characteristics of dispersed flow film boiling.

Heat transfer data are presented for vertical upflow of nitrogen in an electrically heated tube, in. I.D. and 8 ft long. Heat fluxes up to 18, Btu/ft 2-hr .