Rewetting Velocity of High-Temperature Vertical-Narrow Annular Flow-Passage under Counter-Current Flow Condition

2002 ◽  
Vol 2002 (0) ◽  
pp. 257-258
Author(s):  
Yasuo Koizumi ◽  
Masanori Tukudo ◽  
Manabu Arai ◽  
Naoki Sakamoto ◽  
Hiroyasu Ohtake
Keyword(s):  
High Temperature ◽  
Flow Condition ◽  
Annular Flow ◽  
Current Flow ◽  
Flow Passage ◽  
Counter Current Flow ◽  
Counter Current

Study on Counter-Current Flow Rewetting in Narrow-Annular Flow Passages

2002 ◽  
Author(s):  
Naoki Sakamoto ◽  
Asanuma Hironobu ◽  
Shimamura Yosihiro ◽  
Tukudo Masanori ◽  
Yasuo Koizumi ◽  
...  
Keyword(s):  
Heat Flux ◽  
Annular Flow ◽  
Current Flow ◽  
Liquid Penetration ◽  
Annular Space ◽  
High Temperature Water ◽  
Counter Current Flow ◽  
Gap Spacing ◽  
Counter Current ◽  
Temperature Water

Rewetting of a hot wall by gravitational liquid penetration into a narrow-annular space was experimentally examined. Experiments were conducted by using R-113 liquid to simulate high-pressure and high-temperature water. When the gap clearance was 5 mm, liquid fell down into the annular space and accumulated in the lower portion of the flow channel. Then, the hot wall was quenched from the bottom by the accumulated liquid. When the gap clearance was less than 1mm, liquid did not penetrate into the space substantially because of the counter-current flow limiting at the top entrance. Therefore, the hot wall was cooled down very slowly and quenching was not perceived distinctly. When the gap clearance was 2 mm, mixed phenomena of the gap clearance 5 mm and 1 mm were observed. The heat transfer characteristics during quenching were quite similar to those in pool boiling. However, the film boiling heat flux and the peak (critical) heat flux tended to decrease with the gap spacing. The rewetting velocity became slow as the gap spacing became narrow. The liquid penetration limiting with the gap spacing might be reflected on this trend.

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