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Post-dryout heat transfer to high-pressure water flowing upward in vertical channels with various flow obstacles
KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.ORCID iD: 0000-0001-5595-1952
2012 (English)In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, Vol. 55, no 25-26, 8020-8031 p.Article in journal (Refereed) Published
Abstract [en]

Post-dryout heat transfer to high pressure water was investigated experimentally in vertical tubes and annuli containing various flow obstacles. The operational conditions during the experiments were as follows: mass flux from 500 to 1750 kg/m(2) s. pressure from 5 to 9 MPa, inlet subcooling from 10 to 40K and heat flux up to 1.5 MW/m(2). Five different test sections were used in experiments: three annular test sections with inner diameter 12.7 mm and outer diameter 24.3 mm, containing cylindrical and grid flow obstacles in the upper part, and two tubular test sections with inner diameter 24.3 mm with and without pin flow obstacles. The heated length in all test sections was 3650 mm. The wall temperature was measured with 88 thermocouples located along the inner rod and the outer tube surfaces. Due to the presence of flow obstacles, only developing post-dryout heat transfer was observed. Selected post-dryout heat transfer correlations were compared to the experimental data. It has been concluded that all tested correlations predict significantly higher wall temperatures than those obtained in the present experiment. A simple correction function to the Saha model has been suggested which significantly improves the agreement between the correlation and the present data.

Place, publisher, year, edition, pages
2012. Vol. 55, no 25-26, 8020-8031 p.
Keyword [en]
Post-dryout, Dryout, Heat transfer, Flow obstacles
National Category
Other Physics Topics
URN: urn:nbn:se:kth:diva-109173DOI: 10.1016/j.ijheatmasstransfer.2012.08.036ISI: 000311196200065ScopusID: 2-s2.0-84867530162OAI: diva2:582774

QC 20130107

Available from: 2013-01-07 Created: 2012-12-21 Last updated: 2014-03-19Bibliographically approved
In thesis
1. Experimental and theoretical study of post-dryout heat transfer in annuli with flow obstacle
Open this publication in new window or tab >>Experimental and theoretical study of post-dryout heat transfer in annuli with flow obstacle
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

An experimental study on post dryout heat transfer regime in annuli with flow obstacles wasconducted in the High-pressure Water Test (HWAT) loop at the Royal Institute of Technologyin Stockholm, Sweden. An annulus with flow obstacles, consisting of two concentric heatedpipes (12.7x24.3) mm, with total heated length equal to 3650 mm was employed as a testsection. The experimental investigations were performed in a wide range of the operationalconditions: mass flux (500-1750) kg/(m2s), inlet subcooling (10-40) K and system pressure(5-7) MPa. The wall superheat was measured at 88 different axial positions. A significanteffect of the flow obstacles on the wall temperature has been observed. A new correlation toevaluate the wall superheat in the post-dryout developing region and downstream of the flowobstacles was suggested. The new approach is taking into account in a combined manner theonset of the dryout point and the flow obstacle location. The coefficients and constants of thecorrelation have been optimized based on 1211 points obtained experimentally. Thecorrelation is applicable starting with the point of the onset of the dryout towards fullydeveloped post-dryout heat transfer regime and shows a correct asymptotical trend. Toaccount for the flow obstacle effect on the critical quality, an expression similar to theLevitan-Lanstman dryout correlation is suggested. The newly developed methodology can beused to predict the wall temperature in the post-dryout heat transfer regime over a wide rangeof mass fluxes and pressures typical for boiling water reactors.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. ix, 53 p.
TRITA-FYS, ISSN 0280-316X ; 2013:60
annulus, flow obstacles, critical heat flux, post-dryout, thermal margins, boiling water reactor
National Category
Physical Sciences
Research subject
urn:nbn:se:kth:diva-143210 (URN)978-91-7501-909-3 (ISBN)
Public defence
2014-03-28, FB42, AlbaNova, Roslagstullsbacken 29, Stockholm, 10:00 (English)

QC 20140319

Available from: 2014-03-19 Created: 2014-03-18 Last updated: 2014-03-24Bibliographically approved

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Anghel, Ionut GheorgheAnglart, Henryk
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