ISSN Online: 2377-424X
ISBN Print: 978-1-56700-421-2
International Heat Transfer Conference 15
Effect of Flow Pattern on Critical Heat Flux
Sinopsis
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.
PALABRAS CLAVE:
Two-phase/Multiphase flow, Boiling and evaporation, Critical heat flux, flow pattern, convective boiling