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Title: Effect of surface oxidation on the onset of nucleate boiling in a materials test reactor coolant channel

The onset of nucleate boiling (ONB) serves as the thermal-hydraulic operating limit for many research and test reactors. However, boiling incipience under forced convection has not been well-characterized in narrow channel geometries or for oxidized surface conditions. This study presents experimental data for the ONB in vertical upflow of deionized (DI) water in a simulated materials test reactor (MTR) coolant channel. The channel gap thickness and aspect ratio were 1.96 mm and 29:1, respectively. Boiling surface conditions were carefully controlled and characterized, with both heavily oxidized and native oxide surfaces tested. Measurements were performed for mass fluxes ranging from 750 to 3000 kg/m 2s and for subcoolings ranging from 10 to 45°C. ONB was identified using a combination of high-speed visual observation, surface temperature measurements, and channel pressure drop measurements. Surface temperature measurements were found to be most reliable in identifying the ONB. For the nominal (native oxide) surface, results indicate that the correlation of Bergles and Rohsenow, when paired with the appropriate single-phase heat transfer correlation, adequately predicts the ONB heat flux. Furthermore, incipience on the oxidized surface occurred at a higher heat flux and superheat than on the plain surface.
 [1] ;  [2] ;  [2] ;  [2] ;  [2]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Publication Date:
Report Number(s):
SAND-2015-6704J; SAND-2015-2282J
Journal ID: ISSN 2332-8983; 598838
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Nuclear Engineering and Radiation Science
Additional Journal Information:
Journal Volume: 2; Journal Issue: 2; Journal ID: ISSN 2332-8983
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; research reactor; thermal hydraulics; boiling incipience; flow boiling; narrow channel; pressure; temperature; bubbles; boiling; forced convection; temperature measurement; water; heat flux; flow (dynamics); flux (metallurgy)
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1333853