Reflooding With Steady and Oscillatory Injection: Part I—Flow Regimes, Void Fraction, and Heat Transfer

[+] Author and Article Information
M. Kawaji, Y. S. Ng

Department of Nuclear Engineering, University of California, Berkeley, Calif. 94720

S. Banerjee

Department of Chemical and Nuclear Engineering, University of California, Santa Barbara, Calif. 93106

G. Yadigaroglu

Swiss Federal Institute of Technology, ETH-Zentrum, CH-8092 Zürich, Switzerland

J. Heat Transfer 107(3), 670-678 (Aug 01, 1985) (9 pages) doi:10.1115/1.3247476 History: Received January 18, 1984; Online October 20, 2009


Simultaneous void fraction and wall temperature measurements were made during bottom-reflooding of a vertical Inconel tube under both constant and oscillatory injection rates. To support interpretation of these data, flow regime visualization experiments were also conducted by reflooding a heated quartz tube. With constant, high reflooding rates, inverted annular, transition, and dispersed flow regimes exist above the quench front, with typical chordal-average void fractions in the ranges of 10–30 percent, 30–70 percent, and 70–90 percent, respectively. Each regime exhibits different heat transfer rates. With lower injection rates or higher heating rates, annular droplet and dispersed flow regimes appear with void fractions above 80 percent. For reflooding with oscillatory inlet flow and high injection rates, large oscillations are seen in void fraction and wall temperature, indicating periodic changes in the flow regime near the quench front: The regime alternated between inverted annular (during an upstroke) and annular droplet flow (during a downstroke). These flow regimes were observed in the flow visualization experiments to be qualitatively similar to those for the constant injection cases. Heat transfer rates are substantially affected by the flow regime and increase (or decrease) as the void fraction falls (or rises). Compared to the constant-injection tests, increased rates of entrainment were observed during the forced-oscillation tests.

Copyright © 1985 by ASME
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