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Research Papers: Nuclear Power

Subcooled Water Flow Boiling Heat Transfer in a Short SUS304-Tube With Twisted-Tape Insert

[+] Author and Article Information
Koichi Hata1

Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japanhata@iae.kyoto-u.ac.jp

Suguru Masuzaki

 National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292, Japanmasuzaki@lhd.nifs.ac.jp

1

Corresponding author.

J. Eng. Gas Turbines Power 133(5), 052906 (Dec 13, 2010) (11 pages) doi:10.1115/1.4002405 History: Received July 01, 2010; Revised August 02, 2010; Published December 13, 2010; Online December 13, 2010

The subcooled boiling heat transfer and the steady-state critical heat fluxes (CHFs) in a short SUS304-tube with twisted-tape insert are systematically measured for mass velocities (G=401613,850kg/m2s), inlet liquid temperatures (Tin=285.82363.96K), outlet pressures (Pout=764.76889.02kPa), and exponentially increasing heat input (Q=Q0exp(t/τ), τ=8.5s) by the experimental water loop comprised of a multistage canned-type circulation pump controlled by an inverter. The SUS304 test tube of inner diameter (d=6mm), heated length (L=59.5mm), effective length (Leff=49.1mm), L/d(=9.92), Leff/d(=8.18), and wall thickness (δ=0.5mm) with average surface roughness (Ra=3.18μm) is used in this work. The SUS304 twisted tape with twist ratio, y(=H/d=(pitchof180degrotation)/d), of 3.39 is used. The relation between inner surface temperature and heat flux for the SUS304-tube with the twisted-tape insert are clarified from nonboiling to CHF. The subcooled boiling heat transfer for SUS304-tube with the twisted-tape insert is compared with our empty SUS304-tube data and the values calculated by our and other workers’ correlations for the subcooled boiling heat transfer. The influences of the twisted-tape insert and the swirl velocity on the subcooled boiling heat transfer and the CHFs are investigated into details and the widely and precisely predictable correlations of the subcooled boiling heat transfer and the CHFs for turbulent flow of water in the SUS304-tube with twisted-tape insert are given based on the experimental data. The correlations can describe the subcooled boiling heat transfer coefficients and the CHFs obtained in this work within 25 to +15% difference.

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Figures

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Figure 1

Schematic diagram of experimental water loop

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Figure 2

Vertical cross-sectional view of 6 mm inner diameter test section with the twisted-tape insert

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Figure 3

Photograph of the SUS304 twisted tape coated with epoxy resin

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Figure 4

SEM photograph for the SUS304 test tube of d=6 mm with the rough finished inner surface

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Figure 5

Measurement and data processing system

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Figure 6

Typical heat transfer processes for the SUS304 test tube of d=6 mm and Leff=49.1 mm with the twisted tape of y=3.39 at the swirl velocities of 5.45–18.25 m/s on the exponential period of around 8.5 s

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Figure 7

Typical photograph for SUS304 test tube of d=6 mm burned out in CHF experiment with the twisted tape of y=3.39

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Figure 8

Heat transfer processes for the SUS304 test tubes of d=6 mm and Leff=49.1 mm with the twisted tape of y=3.39 and the empty SUS304 test tube of d=6 mm and Leff=49.1 mm

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Figure 9

Values of n versus swirl velocity for SUS304 test tube with the twisted-tape insert and those versus flow velocity for empty SUS304 and Pt test tubes

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Figure 10

Values of ΔTsat at CHF point versus swirl velocity for SUS304 test tube with the twisted-tape insert and those versus flow velocity for empty SUS304 test tubes of d=3 and 6 mm

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Figure 11

qcr,sub,st versus ΔTsub,out for SUS304 test tube of d=6 mm and L=59.5 mm with the twisted tape of y=3.39 at Pout≅800 kPa

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Figure 12

Ratio of CHF data for SUS304 test tube of d=6 mm and L=59.5 mm with the twisted tape of y=3.39 to the values derived from the outlet CHF correlation for the circular tube with various twisted-tape inserts versus ΔTsub,out at Pout≅800 kPa

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Figure 13

qcr,sub,st versus ΔTsub,in for SUS304 test tube of d=6 mm and L=59.5 mm with the twisted tape of y=3.39 at Pin=775–974 kPa

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Figure 14

Ratio of CHF data for SUS304 test tube of d=6 mm and L=59.5 mm with the twisted tape of y=3.39 to the values derived from the inlet CHF correlation for the circular tube with various twisted-tape inserts versus ΔTsub,in at Pin=775–974 kPa

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Figure 15

Values of (Bosw)cr/(Bosw)con versus swirl velocity for SUS304 test tube with the twisted-tape insert and those of Bocr/Bocon versus flow velocity for empty SUS304 test tubes of d=3 and 6 mm

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