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Sunday, August 9, 2020 | History

2 edition of Fluid to fluid modeling of critical heat flux found in the catalog.

Fluid to fluid modeling of critical heat flux

S. Y. Ahmad

Fluid to fluid modeling of critical heat flux

a compensated distortion model

by S. Y. Ahmad

  • 391 Want to read
  • 30 Currently reading

Published by Chalk River Nuclear Laboratories in Chalk River, Ont .
Written in English

    Subjects:
  • Boiling water reactors.,
  • Criticality (Nuclear engineering) -- Mathematical models.

  • Edition Notes

    Statementby S.Y. Ahmad ; Atomic Energy of Canada Limited.
    SeriesAECL (Series) -- no. 3663
    ContributionsChalk River Nuclear Laboratories., Atomic Energy of Canada Limited.
    Classifications
    LC ClassificationsTK"9001"A4"no.3663
    The Physical Object
    Pagination1 v
    ID Numbers
    Open LibraryOL20806263M

      Computational Fluid Dynamics. Stern Laboratories employs state-of-the-art computer simulation technology to develop realistic models to better understand various engineering problems. [], two-phase flow modeling, Critical Heat Flux (CHF), Conjugate Heat Transfer (CHT), etc. Abstract. The new similarity laws for fluid-to-fluid modeling of two-phase flow critical heat flux (CHF) in horizontal helically coiled tubes were derived based on the dimensional analysis and similarity theory considering the effect of the geometrical parameters on CHF.

    boiling curve when reaching the critical heat flux. This paper not only proposes the micro- channels with anisotropic etching on the () silicon wafer, but also examine the process of fluid flow and heat transfer, especially the mechanism of bubble nucleation. Through the fluid behaviors and the thermal phenomenon discussed in this study.   Figure 3 shows the treatment conditions nanofluids Al 2 O 3-Water for the conditions given heat flux of and W/m 2 with a fraction of its volume by 1%, and for Figure 4 is nanofluids Al 2 O 3-Water with a volume fraction of 3%, and for Figure 5 shows a comparison cooling fluid that normally used in the nuclear reactor of Sub Channel Hexagonal with coolant fluid is water H 2 O.

    use of binary mixture working fluids in gravity-assisted heat pipes are shown to improve the critical heat flux (CHF) and operating performance, more so than with pure fluids. The CHF is responsible for dryout when the pumping rate of a liquid flow structure is not sufficient to provide enough fluid to . REFERENCES. Ahmed, S. Y. () Fluid-to-fluid Modeling of Critical Heat Flux: A Compensated Distortion Model, AECL Report, AECL Bertoletti, S. et al. () Heat Transfer Crisis with Steam-Water Mixtures, Energia Nucleare, 12, 3. Groeneveld, D. C. and Borodin, A. S. () The Occurrence of Slow Dryout in Forced Convective Flow, Second Multi-Phase Flow and Heat Transfer Symposium.


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Fluid to fluid modeling of critical heat flux by S. Y. Ahmad Download PDF EPUB FB2

Fluid-to-fluid modeling of critical heat flux (CHF) is to simulate the CHF behaviors for water by employing low cost modeling fluid, and the flow scaling factor is Cited by: 7.

A series of calculations of the critical heat flux (CHF) fluid to fluid modeling scaling factors were performed to obtain relative data between Ra and water for CHF modeling method.

The pressure range of Ra used in calculation was –Mpa (liquid-gas density ratio –), water-equivalent pressure range 1–: Chang-Nian Chen, Ji-Tian Han, Li Shao, Tien-Chien Jen. MEASUREMENT OF TRANSIEOT CRITICAL HEAT FLUX BY FLUID MODELING.

Iowa State University, Ph.D., Engineering, nuclear University Microfilms, A XEROX Company, Ann Arbor, Michigan THIS DISSERTATION HAS BEEN MICROFILMED EXACTLY AS RECEIVED. Measurement of transient critical heatCited by: 1.

Modeling is of practical importance in reducing the high cost of critical heat flux testing for boiling water power reac-tors. A method widely used is to replace water by a modeling fluid having Fluid to fluid modeling of critical heat flux book lower latent heat of vaporization.

In this paper a generalized technique for such fluid modeling of critical heat flux is developed from classical. "Modeling of Two-Phase Boiling Flow and Critical Heat Flux With the NEK-2P CFD Code." Proceedings of the 25th International Conference on Nuclear Engineering.

Volume 8: Computational Fluid Dynamics (CFD) and Coupled Codes; Nuclear Education, Public Acceptance and Related Issues.

Shanghai, China. July 2–6, VT09A : Adrian Tentner, Prasad Vegendla, Ananias Tomboulides, Aleks Obabko, Elia Merzari, Dillon Shaver. The new similarity laws for fluid-to-fluid modeling of critical heat flux (CHF) in horizontal helically-coiled tubes were derived based on the dimensional analysis and similarity theory considering the effect of the geometrical parameters on CHF.

One of the possible solutions is the application of model fluids, which have much lower critical pressure and critical temperature. Model fluid technique has been widely applied in the thermal-hydraulic studies of nuclear engineering.

In spite of growing activities of heat transfer at supercritical conditions using model fluids, there does. In this work, both dimensional analyses using Buckingham Pi-theorem and scaling of the energy equation have been applied successfully in fluid to fluid modeling for post dry out to model the Freon (Ra) data available in the literature and convert it to water equivalent data.

Also the results are compared with the available data in the literature for water. Tentner, Adrian, Merzari, Elia, and Vegendla, Prasad. "Computational Fluid Dynamics Modeling of Two-Phase Boiling Flow and Critical Heat Flux." Proceedings of the 22nd International Conference on Nuclear Engineering.

Magnetohydrodynamics fluid is considered. Concept of Modeling and analysis of megneto-Carreau fluid with radiative heat flux: Dual solutions about critical point - Habib Ullah, M.

Critical Heat Flux. As was written, in nuclear reactors, limitations of the local heat flux is of the highest importance for reactor safety. For pressurized water reactors and also for boiling water reactors, there are thermal-hydraulic phenomena, which cause a sudden decrease in the efficiency of heat transfer (more precisely in the heat transfer coefficient).

Modeling is of practical importance in reducing the high cost of critical heat flux testing for boiling water power reactors. A method widely used is to replace water by a modeling fluid having a.

Critical heat flux (CHF) describes the thermal limit of a phenomenon where a phase change occurs during heating (such as bubbles forming on a metal surface used to heat water), which suddenly decreases the efficiency of heat transfer, thus causing localised overheating of the heating surface.

The critical heat flux for ignition is the lowest thermal load per unit area capable of initiating a. This paper describes the derivation of a critical heat flux (CHF) lookup table, which may be used for predicting CHF for water over a very wide range of conditions.

The CHF table is based on the Chalk River Nuclear Laboratories' CHF data bank, which contains more. Figure 1. Schematics of a) two fluid flows with different densities in a 2D channel, b) a circular gas jets into a liquid Hydrodynamic theory model The model developed by Zuber[5] was the most widely used to predict the critical heat flux(CHF).

An experimental study on critical heat flux (CHF) in a helically-coiled tube cooled with Ra has been completed in order to assess present fluid-to-fluid modeling approaches. The investigated range of flow parameters for Ra was: pressure from to MPa, mass flux values from 50 to kg m-2 s-1 and inlet quality from to In this article, we aim to analyze the dual solutions for the flow of non-Newtonian material (Carreau fluid) over a radially shrinking surface.

Magnetohydrodyna. describing the wall heat transfer to the vapor. Radiative heat transfer from the wall to the fluid is neglected. The model was compared to data ( points) with a standard deviation of 16%.

The calculated heat flux value for transition boiling is applied to post-CHF heat transfer if it is larger than the value for film boiling. Film Boiling. Dear sir, I have doubts about interfacial constitutive correlations in two-fluid model. Can we use the empirical correlations those are used in lumped analysis (porous media approximation, subchannel level analysis of reactor flow channel) as such into CFD code?For ex.

interfacial area concentration in lumped analysis codes consider as: (4*(vapor fraction)^)/Dh Dh hydraulic diameter. Boiling heat transfer and critical heat flux in liquid films falling on vertically-mounted heat sources also increase, ejecting droplets further downstream on the surface.

CHF occurs when most of the droplets are ejected beyond the downstream edge of the heater. Katto [. CRITICAL HEAT FLUX MODEL IMPROVEMENT IN CTF FOR NATURAL CIRCULATION TYPE REACTORS A Thesis in Nuclear Engineering by Caleb Jernigan © Caleb Jernigan Submitted in Partial Fulfillment regime of the working fluid.

Heat transfer at the rod surface is. Nanofluids (suspensions of nanometer-sized particles in base fluids) have recently been shown to have nucleate boiling critical heat flux (CHF) far superior to that of the pure base fluid. Over the past decade, numerous experimental and analytical studies on the nucleate boiling CHF of nanofluids have been conducted.

The purpose of this article is to provide an exhaustive review of these studies.2 “CRITICAL HEAT FLUX” AND ITS PREDICTION The meaning, and regions of operation of CHF At low to medium heat fluxes, boiling heat transfer is an efficient means of transferring heat from a surface to a fluid flowing over it.

The fluid can either be a sub-cooled liquid (in which.