Research on the Occurring Location of ONB in Narrow Rectangular Channel Under Natural Circulation by Factorial Analysis Method

2016 ◽  
Author(s):  
Shi Qi ◽  
Tao Zhou ◽  
Baixu Chen ◽  
Zejun Xiao
Keyword(s):  
Natural Circulation ◽  
Rectangular Channel ◽  
Nucleate Boiling ◽  
Factorial Analysis ◽  
Important Influence ◽  
Gap Size ◽  
Analysis Method ◽  
The Third ◽  
Natural Circulation Loop ◽  
Factor Interaction

This paper describes the research on the location of Onset of Nucleate Boiling (ONB) in Natural circulation. Selecting the narrow rectangular natural circulation loop as the research object, the occurring location of ONB is analyzed by experiment. By the method of factorial analysis, the influences of different factors and the factor interaction to the location of ONB are studied. The results show that, the inlet subcooling has the biggest influence, whose contribution percentage is 49.8%. The second important influence is the gap size, whose contribution percentage is 25.2%. The third important influence is the heat flux, whose contribution percentage is 24.4%. The influence of factor interaction to the location of ONB are negligible.

Study on Factors Affecting CHF Based on Factorial Analysis in Narrow Rectangular Channel Under Natural Circulation

2018 ◽  
Author(s):  
Li Zichao ◽  
Zhou Tao ◽  
Shi Shun ◽  
Amir Haider ◽  
Li Bing ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Influencing Factors ◽  
Mass Flow ◽  
Flow Rate ◽  
Natural Circulation ◽  
Rectangular Channel ◽  
Factorial Analysis ◽  
Contribution Rate ◽  
Factors Affecting ◽  
System Pressure

Research on influencing factors of CHF in narrow rectangular channel under natural circulation is of great significance to the safety of reactors. Taking the narrow rectangular experimental device as the research object, influencing factors of CHF in narrow rectangular channel were experimentally studied under natural circulation. With factorial analysis, effects of different factors and their interactions on CHF were analyzed. It is found that the contribution rate of mass flow rate is the largest, followed by the effect of outlet dryness, followed by the effect of system pressure. Their interactions between different factors have little effects on CHF in narrow rectangular channel under natural circulation.

Visualization Study on Onset of Nucleate Boiling for Natural Circulation Flow in a Narrow Rectangular Channel

2017 ◽  
Author(s):  
Chunping Tian ◽  
Xiaxin Cao ◽  
Jianjun Wang ◽  
Changqi Yan ◽  
Kuan Yang ◽  
...  
Keyword(s):  
Error Analysis ◽  
Natural Circulation ◽  
Rectangular Channel ◽  
Flow Region ◽  
Nucleate Boiling ◽  
Wall Surface ◽  
Circulation Flow ◽  
Valuable Data ◽  
Entrance Effect

Experiments on onset of nucleate boiling (ONB) have been performed for the natural circulation flow in a one-sided heated narrow rectangular channel. With fast camera putting into use, the visualization study was conducted to capture the location of ONB. The experiments were performed at pressure of 0.2 MPa and 0.3 MPa, with subcooling temperature ranging from 40 to 60 K, and heating flux ranging from 70 to 220 kW/m2. Differing from conventional channel, the superheats of wall surface in the narrow rectangular channel needed for ONB is larger, and can be predicted with Thom’s correlation in developed flow region. Moreover, the superheat needed for ONB will decrease for the existence of entrance effect. The visualization study indicated that the traditional determination of ONB will bring in more error. In this study, valuable data and image have been provided for the error analysis of ONB.

Natural-Circulation Tests With Water at 800 to 2000 Psia Under Nonboiling, Local Boiling, and Bulk Boiling Conditions

1961 ◽  
Vol 83 (3) ◽  
pp. 261-273 ◽  
Author(s):  
O. J. Mendler ◽  
A. S. Rathbun ◽  
N. E. Van Huff ◽  
A. Weiss
Keyword(s):  
Heat Flux ◽  
Natural Circulation ◽  
Rectangular Channel ◽  
Heat Fluxes ◽  
Circulation Loop ◽  
Flow Conditions ◽  
Two Phase ◽  
Forced Circulation ◽  
Flow Fluctuations ◽  
Natural Circulation Loop

Natural and forced-circulation test data for a closed-loop system are presented and analyzed. The data were obtained at pressures of 800, 1200, 1600, and 2000 psia from the natural-circulation loop at the Bettis Laboratory, using single rectangular channel test sections (0.100 in. × 1.0 in. × 27.0 in. long, 0.200 in. × 1.0 in. × 27.0 in. long, and 0.250 in. × 1.0 in. × 27.0 in. long). Heat fluxes ranged from 50,000 Btu/hr-sq ft to burnout with inlet subcoolings of 20, 70, and 100 deg F. The results showed that single and two-phase pressure drop, burnout heat flux, and riser density measured under natural-circulation operation are no different from those measured with forced circulation at the same thermal and fluid flow conditions. For the loop studied, it was shown that natural-circulation-loop flow rates can be predicted to within 10 per cent for both single and two-phase flow. Some data for slip ratios at liquid velocities less than 1/2 fps and for two-phase exit losses were obtained. Flow fluctuations were noted during some of the natural-circulation runs; these occurred before burnout heat flux was reached. In some instances these fluctuations were severe enough to cause a premature burnout.

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