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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Effect of Flow Pattern on Critical Heat Flux

Get access (open in a dialog) DOI: 10.1615/IHTC15.tpf.009376
pages 8471-8482

Resumo

Critical heat flux (CHF) is one of important design factors in boiling two-phase flow equipment, such as a boiler and steam generator of nuclear reactor. CHF can be explained through mainly two mechanisms, i.e. Dryout and DNB, but other mechanisms are also observed under some conditions. The detailed mechanism of CHF is strongly related to the flow pattern. In this study, to understand the effect of flow pattern on CHF under concentrated high heat flux condition, the experimental investigation was conducted by using forced convective boiling system. The test section consisted of two heating sections, a pre-heater for control of flow pattern and a main heating section for CHF experiment. As a result, on the basis of the temperature movements, CHF mechanism was classified into three patterns, and these characteristics could be correlated with the flow pattern. Moreover, the CHF characteristics could be explained well by using the interface instability model of slug flow, the transition criteria of churn-annular flow, the film flow model of annular flow and Katto's correlation of CHF.