Access count of this item: 306

Files in This Item:
File Description SizeFormat 
j.nucengdes.2008.12.001.pdf1.66 MBAdobe PDFView/Open
Title: Influence of heat input waveform on transient critical heat flux of subcooled water flow boiling in a short vertical tube
Authors: Hata, Koichi
Masuzaki, s.
Author's alias: 畑, 幸一
Issue Date: Feb-2010
Publisher: Elsevier
Journal title: Nuclear Engineering and Design
Volume: 240
Issue: 2
Start page: 440
End page: 452
Abstract: The transient critical heat fluxes (CHFs) of the subcooled water flow boiling for ramp-wise heat input [Q = αt, α = 6.21 × 108 to 1.63 × 1012 W/m3 s, (q 1.08 × 107 to 6.00 × 107 W/m2)] and stepwise one [Q = Qs, Qs = 0 W/m3 at t = 0 s and Qs = 2.95 × 1010 to 7.67 × 1010 W/m3 at t > 0 s, (q = 0 W/m2 at t = 0 s and q 1.61 × 107 to 3.87 × 107 W/m2 at t > 0 s)] with the flow velocities (u = 4.0–13.3 m/s), the inlet subcoolings (ΔTsub, in = 86.8–153.3 K) and the inlet pressures (Pin = 742.2–1293.4 kPa) are systematically measured by an experimental water loop comprised of a pressurizer. The SUS304 tubes of inner diameters (d = 3, 6 and 9 mm), heated lengths (L = 33.15, 59.5 and 49.3 mm), L/d (=11.05, 9.92 and 5.48), and wall thickness (δ = 0.5, 0.5 and 0.3 mm) respectively with the rough finished inner surface (surface roughness, Ra = 3.18 μm) are used in this work. The experimental errors in the subcooling measure and the pressure one are ±1 K and ±1 kPa, while in the heat flux it is ±2%. The transient CHF data for the ramp-wise heat input and the stepwise one are compared with those for the exponentially increasing heat input (Q = Q0 exp(t/τ), τ = 16.82 ms to 15.52 s) previously obtained and the dominant variables on transient CHF for heat input waveform difference are confirmed. The transient CHF data are compared with the values calculated by the steady state CHF correlations against inlet and outlet subcoolings, and the applicability of steady state CHF correlations is confirmed extending its possible validity for the reduced time, ωp, down to 800 ms. The transient CHF data are compared with the values calculated by the transient CHF correlations against inlet and outlet subcoolings, and the influence of heat input waveform on transient CHF is clarified based on the experimental data for the ramp-wise heat input, the stepwise one and the exponentially increasing one. The dominant mechanisms of the subcooled flow boiling critical heat flux for the ramp-wise heat input, the stepwise one and the exponentially increasing one are discussed.
Rights: c 2008 Elsevier B.V. All rights reserved.
This is not the published version. Please cite only the published version. この論文は出版社版でありません。引用の際には出版社版をご確認ご利用ください。
URI: http://hdl.handle.net/2433/91253
DOI(Published Version): 10.1016/j.nucengdes.2008.12.001
Appears in Collections:Journal Articles

Show full item record

Export to RefWorks


Export Format: 


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.