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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 Engineering Sciences (SCI), Physics, Reactor Technology.
2010 (English)In: International Conferecne Nulclear Energy for New Europa 2010, 2010Conference paper, Published paper (Other (popular science, discussion, etc.))
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/(m2s), 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 postdryout heat transfer in channels with flow obstacles.

 

Place, publisher, year, edition, pages
2010.
National Category
Energy Engineering
Identifiers
URN: urn:nbn:se:kth:diva-44531OAI: oai:DiVA.org:kth-44531DiVA: diva2:450970
Note
QC 20111024Available from: 2011-10-24 Created: 2011-10-24 Last updated: 2011-10-24Bibliographically approved
In thesis
1. Experimental Study of Post-Dryout Heat Transferin Annuli with Flow Obstacles
Open this publication in new window or tab >>Experimental Study of Post-Dryout Heat Transferin Annuli with Flow Obstacles
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

An experimental study on post dryout heat transfer regime in annuli with flow obstacles was conducted in the High-pressure Water Test (HWAT) loop at the Royal Institute of Technology in Stockholm, Sweden. An annulus consisting of two concentric heated pipes (12.7x24.3) mm, with total heated length equal to 3650 mm was employed as a test section. Three kinds of flow obstacles were used: pin-spacers, cylindrical obstacles and grid obstacles. The experiments performed in the test section with pin-spacers only were considered as the reference case. In two consecutive sets of runs, additional obstacles were placed inside the flow channel while keeping the pin spacers in the same positions. In that way the net effect of obstacles on heat transfer was measured. The experimental investigations were performed in a wide range of the operational conditions: 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 (40 on the inner tube and 48 on the outer tube) for the conditions mentioned above. A local heat transfer coefficient was calculated based on the measured annulus wall temperatures and the saturated fluid (water) properties. The results show an enhancement of the heat transfer coefficient downstream of flow obstacles. The most significant influence has been observed in case of pin spacers. This result is consistent with blockage area of various obstacles, which was the highest in case of pin spacers. The data obtained in more than 200 runs were compared with two pre-dryout and post-dryout correlations. The correlations show a slight over-prediction of the heat transfer coefficient in both pre-dryout and post-dryout regions. The thesis contains a detailed description of experimental procedures as well as an analysis of the results of measurements.

 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. vii, 39 p.
Series
Trita-FYS, ISSN 0280-316X ; 2011:20
Keyword
annulus, post-dryout, temperature distribution, flow obstacles, new measurements
National Category
Energy Engineering
Research subject
SRA - Energy
Identifiers
urn:nbn:se:kth:diva-44071 (URN)978-91-7501-020-5 (ISBN)
Presentation
2011-06-10, FB55, AlbaNova UniversitesCentrum , Roslagstullsbacken 21, SE-10691, Stockholm, 09:44 (Swedish)
Opponent
Supervisors
Projects
SKC: Post Dryout Regime
Funder
StandUp
Note
QC 20111024Available from: 2011-10-24 Created: 2011-10-20 Last updated: 2011-10-24Bibliographically approved

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Anglart, Henryk

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