Conductive and viscous sub-layers on forced convection and mechanism of critical heat flux during flow boiling of subcooled water in a platinum circular tube with 3 mm inner diameter and 32.7 mm heated length at high liquid Reynolds number

2020 ◽  
Vol 162 ◽  
pp. 120269
Author(s):  
K. Hata ◽  
Q.S. Liu
Keyword(s):  
Heat Flux ◽  
Reynolds Number ◽  
Forced Convection ◽  
Critical Heat Flux ◽  
Circular Tube ◽  
Flow Boiling ◽  
Subcooled Water ◽  
Inner Diameter ◽  
Heated Length

Correlation for Flow Boiling Critical Heat Flux in Thin Rectangular Channels

2009 ◽  
Vol 131 (12) ◽  
Author(s):  
Futoshi Tanaka ◽  
Takashi Hibiki ◽  
Kaichiro Mishima
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Flow Boiling ◽  
Rectangular Channels ◽  
Hydraulic Design ◽  
Wide Range ◽  
Outlet Flow ◽  
Triggering Mechanisms ◽  
Small Channels ◽  
Heated Length

The effect of heated length on critical heat flux (CHF) in thin rectangular channels under atmospheric pressure has been studied. CHF in small channels has been widely studied in the last decades but most of the studies are based on flow in round tubes and number of studies focused on rectangular channels is relatively small. Although basic triggering mechanisms, which lead to CHF in thin rectangular channels, are similar to that of tubes, applicability of thermal hydraulic correlations developed for tubes to rectangular channels are questionable since heat transfer in rectangular channels are affected by the existence of nonheated walls and the noncircular geometry of channel circumference. Several studies of CHF in thin rectangular channels have been reported in relation to thermal hydraulic design of research reactors and neutron source targets and correlations have been proposed, but the studies mostly focus on geometrical conditions of the application of interest and therefore effect of channel parameters exceeding their interest is not fully understood. In his study, CHF data for thin rectangular channels have been collected from previous studies and the effect of heated length on CHF was examined. Existing correlations were verified with data with positive quality outlet flow but none of the correlations successfully reproduced the data for a wide range of heated lengths. A new CHF correlation for quality region applicable to a wide range of heated lengths has been developed based on the collected data.

scholarly journals Critical Heat Flux of Flowing Water in Tube for Pressure Up to Near Critical Point—Experiment and Prediction

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Yuzhou Chen ◽  
Minfu Zhao ◽  
Keming Bi ◽  
Bin Yang ◽  
Dongxu Zhang ◽  
...  
Keyword(s):  
Heat Flux ◽  
Critical Point ◽  
Critical Heat Flux ◽  
Previous Experiment ◽  
Empirical Relation ◽  
Total Power ◽  
Uniform Heating ◽  
Local Quality ◽  
Inner Diameter ◽  
Heated Length

Critical heat flux (CHF) experiment with uniform heating was performed in a tube of 8.2 mm in inner diameter and 2.4 m in heated length. The water flowed upward through the test section. The pressure covered the range from 8.6 to 20.8 MPa, mass flux 1157 to 3776 kg/m2s, inlet quality −2.79 to −0.08 (subcooling 19–337 °C), and local quality −0.97 to 0.53. For the pressure close to the near-critical point, the CHF decreased substantially with the pressure increasing. For the subcooling larger than a certain value, the CHF was related to the local condition. But for low subcooling and saturated condition, the CHF was related to the total power. The present results were in agreement with the previous experiment for the same local subcooled condition. Based on the present experimental results with subcooled and saturated conditions an empirical relation of the CHF was presented.

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