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2014
EXPERIMENTAL DATA ON PHASE DISTRIBUTION IN THE UPWARD HIGH PRESSURE STEAM-WATER FLOWIN A VERTICAL TUBE UNDER ANNULAR-DISPERSED REGIME. PART 2. STRUCTURAL AND LOCAL HYDRODYNAMIC CHARACTERISTICS OF FLOW
83-137
10.1615/MultScienTechn.v26.i2.10
P. L.
Kirillov
State Scientific Center of Russian Federation−Institute for Physics & Power Engineering, 249033 Obninsk, Kaluga Region, Russian Federation
Yu. Yu.
Shtein
State Scientific Center of Russian Federation−Institute for Physics & Power Engineering, 249033 Obninsk, Kaluga Region, Russian Federation
R. V.
Shumsky
State Scientific Center of Russian Federation−Institute for Physics & Power Engineering, 249033 Obninsk, Kaluga Region, Russian Federation
Yu. D.
Levchenko
State Scientific Center of Russian Federation−Institute for Physics & Power Engineering, 249033 Obninsk, Kaluga Region, Russian Federation
upward steam-water flow
vertical tube
high pressure
annulardispersed regime
liquid film thickness
shear stress
mean density of mixture
frictional pressure drop
void fraction
database
experimental data
tabular form
Results of experimental research of the local hydrodynamic characteristics of the upward steam-water flow in a vertical tube with the internal diameter of 13 and 17 mm under pressure of 4.9-13.7 MPa are considered. In the course of these experiments, the geometrical liquid film parameters, frictional pressure drop (ΔPfr), shear stress at a channel wall, the mean actual volumetric void fraction (φsub>vol), and the cross-sectional average void fraction (φc-s) were determined. It was found that the frictional pressure drop in the upward high pressure two-phase flow under the fully developed annular-dispersed regime can be calculated as in the case of the single-phase flow in tubes with the regular roughness. The calculated values of ΔPfr are in agreement with the experimental data within ±15%. Ten correlations were evaluated against the experimental data on the void fraction φc-s. The Cioncolini-Thome equation for void fraction in the annular two-phase flow provides the best prediction among them with accuracy ±2.6%. The database containing about 3000 experimental points is given in
tabular forms (see Parts 1 and 2 of this paper).
SATURATION AND SUBCOOLED CHF CORRELATIONS FOR PF-5060 DIELECTRIC LIQUID ON INCLINED ROUGH COPPER SURFACES
139-170
10.1615/MultScienTechn.v26.i2.20
Mohamed S.
El-Genk
Institute for Space and Nuclear Power Studies; Mechanical Engineering Department; Nuclear Engineering Department, Chemical & Biological Engineering Dept., University of New Mexico, Albuquerque, New Mexico, 87131 USA
Arthur
Suszko
Institute for Space and Nuclear Power Studies, Mechanical Engineering Dept., University of New Mexico, Albuquerque, NM, USA
CHF
dielectric liquids
immersion cooling
nucleate boiling
liquid subcooling
surface roughness and inclination
Pool-boiling experiments investigated the critical heat flux (CHF) for degassed PF-5060 dielectric liquid on inclined and uniformly heated 10×10 mm rough copper (Cu) surfaces. The experiments tested 13 surfaces with average roughness, Ra = 0.039 (smooth-polished), 0.134, 0.21, 0.28, 0.33, 0.58, 0.71, 0.80, 0.925, 1.00, 1.21, 1.44, and 1.79 μ;m, at inclination angles, θ = 0° (upward facing);
60°, 90° (vertical); and 120°, 150°, 160°, 170°, and 180° (downward facing). In addition, liquid subcooling
in the experiments, ΔTsub, varied from 0 K (saturation) to 30 K. The CHF increased with
increasing both surface roughness and liquid subcooling, but decreased with increasing inclination
angle. For all inclinations, CHFsat on the roughest surface is ~35% higher than on the smoothpolished Cu. Moreover, regardless of Ra, CHFsat values in the downward facing orientation (180°)
are typically ~31% of those in the upward facing orientation (0°). CHF in the upward facing orientation
increases linearly with increasing liquid subcooling at a rate of ~2.2%/K, independent of
Ra. This rate increases with increasing the inclination angle to as much as 4%/K in the downward
facing orientation. The developed CHF correlation based on the present database accounts for surface
roughness and inclination angle, and the liquid's subcooling and physical properties and agrees with
the experimental data to within ±10%.