Characteristics of critical heat flux in two phase thermosyphon - relationship between maximum falling liquid rate and instability on interface of falling liquid film

1998 ◽  
Vol 34 (2-3) ◽  
pp. 135-142 ◽  
Author(s):  
S. Mihara ◽  
M. Monde
Keyword(s):  
Heat Flux ◽  
Liquid Film ◽  
Critical Heat Flux ◽  
Two Phase ◽  
Falling Liquid Film

H222 Critical Heat Flux of Counter-Current Two-Phase Flow : Effect of Subcooled Liquid Film

2011 ◽  
Vol 2011 (0) ◽  
pp. 371-372
Author(s):  
Ayaka Fujiwara ◽  
Takuya Suzuki ◽  
Takeyuki Ami ◽  
Hisashi Umekawa ◽  
Mamoru Ozawa
Keyword(s):  
Heat Flux ◽  
Liquid Film ◽  
Critical Heat Flux ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Subcooled Liquid ◽  
Flow Effect ◽  
Counter Current

Experimental Study on Liquid Film Dryout Under Oscillatory Flow Conditions

2009 ◽  
Author(s):  
Yosuke Yamagoe ◽  
Taisuke Goto ◽  
Tomio Okawa
Keyword(s):  
Heat Flux ◽  
Liquid Film ◽  
Power Density ◽  
Critical Heat Flux ◽  
Boiling Water ◽  
Boiling Water Reactors ◽  
Flow Oscillation ◽  
Two Phase ◽  
Water Reactors ◽  
Liquid Film Dryout

The use of high power density core is one of the promising ways to improve economic efficiency of advanced boiling water reactors. It is however known that in boiling two-phase flows, an increase in power density commonly reduces the margin to the onset of unanticipated flow instability. Hence, in the development of a boiling water reactor of high power density core, ability to predict the occurrence of boiling transition is considered indispensable even when the coolant flow rate is not in the steady state. In the present work, sinusoidal oscillation was applied to the inlet mass flux and the experimental measurement of the critical heat flux was carried out under flow oscillation conditions. It was shown that the critical heat flux decreases monotonically with increased values of oscillation amplitude and oscillation period. These results are consistent with experimental data reported by previous investigators. A simple theory was then proposed to estimate the critical heat flux in oscillatory flow condition. Considering the application to the advanced boiling water reactors, the triggering mechanism of the critical heat flux condition is supposed to be the liquid film dryout in annular two-phase flow regime of high vapor quality. Under the flow oscillation condition, it is expected that long waves are formed on a liquid film due to the time variation of inlet mass flux. Assuming that the wave evolution within a boiling channel is influential in the occurrence of the local dryout of a liquid film, an available nonlinear wave theory was applied to the estimation of critical heat flux under the flow oscillation condition. It was demonstrated that the critical heat fluxes measured under the oscillatory conditions agree with the proposed theory fairly well.

scholarly journals Liquid film–induced critical heat flux enhancement on structured surfaces

2021 ◽  
Vol 7 (26) ◽  
pp. eabg4537
Author(s):  
Jiaqi Li ◽  
Daniel Kang ◽  
Kazi Fazle Rabbi ◽  
Wuchen Fu ◽  
Xiao Yan ◽  
...  
Keyword(s):  
Heat Flux ◽  
Liquid Film ◽  
Critical Heat Flux ◽  
Thin Liquid Film ◽  
Bubble Formation ◽  
Contact Lines ◽  
Bubble Behavior ◽  
Two Phase ◽  
Structured Surfaces ◽  
Bubble Evolution

Enhancing critical heat flux (CHF) during boiling with structured surfaces has received much attention because of its important implications for two-phase flow. The role of surface structures on bubble evolution and CHF enhancement remains unclear because of the lack of direct visualization of the liquid- and solid-vapor interfaces. Here, we use high-magnification in-liquid endoscopy to directly probe bubble behavior during boiling. We report the previously unidentified coexistence of two distinct three-phase contact lines underneath growing bubbles on structured surfaces, resulting in retention of a thin liquid film within the structures between the two contact lines due to their disparate advancing velocities. This finding sheds light on a previously unidentified mechanism governing bubble evolution on structured surfaces, which has notable implications for a variety of real systems using bubble formation, such as thermal management, microfluidics, and electrochemical reactors.

Critical heat flux and the dryout of liquid film in vertical two-phase annular flow

2021 ◽  
Vol 177 ◽  
pp. 121487
Author(s):  
R.W. Morse ◽  
T.A. Moreira ◽  
J. Chan ◽  
K.M. Dressler ◽  
G. Ribatski ◽  
...  
Keyword(s):  
Heat Flux ◽  
Liquid Film ◽  
Critical Heat Flux ◽  
Annular Flow ◽  
Two Phase

Liquid film dryout model for predicting critical heat flux in annular two-phase flow

2009 ◽  
Vol 10 (3) ◽  
pp. 398-417 ◽  
Author(s):  
Bo Jiao ◽  
Li-min Qiu ◽  
Jun-liang Lu ◽  
Zhi-hua Gan
Keyword(s):  
Heat Flux ◽  
Liquid Film ◽  
Critical Heat Flux ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Liquid Film Dryout
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