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Experimental investigation of post-dryout heat transfer in annuli with 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
KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
2012 (English)In: Nuclear Engineering and Design, ISSN 0029-5493, E-ISSN 1872-759X, Vol. 246, 82-90 p.Article in journal (Refereed) Published
Abstract [en]

An experimental study on post-dryout heat transfer was conducted in the High-pressure WAter Test (HWAT) loop at the Royal Institute of Technology in Stockholm, Sweden. The objective of the experiments was to investigate the influence of flow obstacles on the post-dryout heat transfer. The investigated operational conditions include mass flux equal to 500 kg/m2 s, inlet sub-cooling 10 K and system pressure 5 and 7 MPa. The experiments were performed in annuli in which the central rod was supported with five pin spacers. Two additional types of flow obstacles were placed in the exit part of the test section: a cylinder supported on the central rod only and a typical BWR grid spacer cell. The measurements indicate that flow obstacles improve heat transfer in the boiling channel. It has been observed that the dryout power is higher when additional obstacles are present. In addition the wall temperature in post-dryout heat transfer regime is reduced due to increased turbulence and drop deposition. The present data can be used for validation of computational models of post-dryout heat transfer in channels with flow obstacles.

Place, publisher, year, edition, pages
Elsevier, 2012. Vol. 246, 82-90 p.
Keyword [en]
Post-dryout, flow obstacles, high spatial resolution
National Category
Fluid Mechanics and Acoustics
Research subject
SRA - Energy
URN: urn:nbn:se:kth:diva-84231DOI: 10.1016/j.nucengdes.2011.08.026ISI: 000303223000011ScopusID: 2-s2.0-84859218375OAI: diva2:499282
Experimental Study of Post- Dryout Heat Transfer in Annulus with Flow Obstacles

This is the author’s version of a work that was accepted for publication in Nuclear Engineering and Design. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Nuclear Engineering and Design, (30 August 2011) DOI: 10.1016/j.nucengdes.2011.08.026,” Qc 20120215

Available from: 2012-02-15 Created: 2012-02-13 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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