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ISSN Online: 2377-424X

ISBN Print: 1-56032-797-9

International Heat Transfer Conference 11
August, 23-28, 1998, Kyongju, Korea

CRITICAL HEAT FLUX FOR OSCILLATORY WATER FLOW IN VERTICAL ROUND TUBES

Get access (open in a dialog) DOI: 10.1615/IHTC11.2070
pages 9-14

Abstract

Boiling systems often show flow oscillations under natural circulation and/or low-pressure conditions. It is well known that How oscillations can induce a premature critical heat flux (CHF) at the heat flux level much lower than that for stable conditions.
In this work, the flow oscillation effects on CHF are investigated for water flow in vertical round tubes at low-pressure, low-flow (LPLF) conditions. Experiment has been conducted to investigate the difference in CHF between forced and natural circulation, and between stable and oscillating flow conditions. Tests have been performed with three (3) vertical round tube test sections (5.0 mm ID x 0.6 m long, 6.6 mm ID x 0.5 long and 9.8 mm ID × 0.6 m long) for mass fluxes below 400 kg/m2s under near atmospheric pressure. It is found that flow oscillations can drastically reduce the CHF, in particular for natural-circulation conditions.
In addition to the experiment, flow-oscillation CHF correction factors are developed for forced and natural circulation, respectively, based on the experimental data of the present work and others.