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Measurements of Film Flow Rate in Heated Tubes with Various Axial Power Distributions
KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
2006 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

Measurements of film mass flow rate for annular, diabatic steam-water flow in tubes are presented. The measurements were carried out with four axial power distributions and at several axial positions at conditions typical for boiling water reactors, i.e. 7 MPa pressure and total mass flux in a range from 750 to 1750 kg/m2s. The results show that the influence of the axial power distribution on the dryout power corresponds to a consistent tendency in the film flow rate and that the film tends to zero when dryout is approached. Furthermore it is demonstrated that two selected phenomenological models of annular flow well predict the present data. A model for additional entrainment due to boiling is shown to degrade the predictions.

Place, publisher, year, edition, pages
Stockholm: Fysik , 2006. , vi, 27 p.
Keyword [en]
film flow, film thickness, dryout, power distribution, annular flow
National Category
Atom and Molecular Physics and Optics
Identifiers
URN: urn:nbn:se:kth:diva-3881ISBN: 91-7178-279-6 (print)OAI: oai:DiVA.org:kth-3881DiVA: diva2:9855
Presentation
2006-03-13, sem.rum 112:028, AlbaNova, Roslagstullbacken 11, Stockholm, 10:10
Opponent
Supervisors
Note
QC 20101108Available from: 2006-03-15 Created: 2006-03-15 Last updated: 2010-11-08Bibliographically approved
List of papers
1. Measurements of the Liquid Film Flow Rate in High Pressure Annular Flow with Various Axial Power Distributions
Open this publication in new window or tab >>Measurements of the Liquid Film Flow Rate in High Pressure Annular Flow with Various Axial Power Distributions
2005 (English)In: HEAT 2005, Gdansk, Poland, June 26–30, 2005, 2005Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents film flow measurement technique and the results with uniform power distribution. Based on these measurements it is possible to estimate the critical film thickness. The measured film thickness was plotted versus steam quality and slightlyextrapolated up to the measured critical steam quality. The conclusions werein line with Hewitt et al. (1965), i.e. that the critical film thickness is insignificantly small. This does not contradict e.g. Ueda & Isayama (1981) since the conditions were not the same, but for the flow conditions and heat fluxes that are typical for BWR operation it was concluded that the critical film thickness is, for practical purposes, zero.

Keyword
Film flow analysis, Measurements
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-13426 (URN)
Note
QC 20100618Available from: 2010-06-18 Created: 2010-06-18 Last updated: 2010-11-08Bibliographically approved
2. Eperimental Investigation of the Liquid Film for Annular Flow in a Tube with Various Axial Power Distributions
Open this publication in new window or tab >>Eperimental Investigation of the Liquid Film for Annular Flow in a Tube with Various Axial Power Distributions
2005 (English)In: NURETH 11, Avignon, France, October 2–6, 2005, 2005Conference paper, Published paper (Refereed)
Abstract [en]

This paper was published when the measurements with non-uniform powerdistribution were still ongoing. Therefore only the measurements with uniformand top-peaked power profiles were included. The paper compares the measured data with deposition and entrainmentmodels by Hewitt & Govan (1990) and Okawa et al. (2003). These models are also discussed in Sections 4.2.1 and 4.2.2. The issue of a correct boundarycondition at the onset of annular flow was avoided by starting the integrationof the film flow model from the most upstream measurement point. In this way the net mass exchange rate (deposition less entrainment) could be studied without any initial bias from the boundary condition.The entrainment correlation proposed by Okawa et al. (2003) included a heat flux dependent term to account for boiling entrainment (Section 4.2.2). Paper 2 concludes that the model agrees better with measurements if this term is omitted. The result suggests that boiling entrainment may not be an important effect at the investigated conditions.

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-13428 (URN)
Note
QC 20100618Available from: 2010-06-18 Created: 2010-06-18 Last updated: 2010-11-08Bibliographically approved
3. Film flow measurements for high-pressure diabatic annular flow in tubes with various axial power distributions
Open this publication in new window or tab >>Film flow measurements for high-pressure diabatic annular flow in tubes with various axial power distributions
2006 (English)In: Nuclear Engineering and Design, ISSN 0029-5493, E-ISSN 1872-759X, Vol. 236, no 23, 2485-2493 p.Article in journal (Refereed) Published
Abstract [en]

Measurements of film flow rates in diabatic annular flow in tubes with various axial power distributions were carried out in the high-pressure two-phase flow loop at the Royal Institute of Technology (KTH), Sweden. The measurements were performed at conditions typical for boiling water reactors, i.e. 7 MPa pressure and total mass flux in a range from 750 to 1750 kg/m(2)s. Four different axial power distributions were used and the film mass flow was measured at 7 axial locations for each set of boundary conditions. The results show that the outlet peaked distribution gives less film than the inlet peaked one. This result is consistent with well known trends from measurements of dryout power. The measurements also show that the film flow at the onset of dryout is very small at investigated conditions in agreement with earlier studies. Finally it is shown that the present data is well predicted by two selected phenomenological models of annular flow.

Keyword
Axial power distributions, Film flow measurements, Mass flow
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-13430 (URN)10.1016/j.nucengdes.2006.03.002 (DOI)000241899800007 ()2-s2.0-33749614541 (Scopus ID)
Note
QC 20100618Available from: 2010-06-18 Created: 2010-06-18 Last updated: 2010-11-08Bibliographically approved

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