Analysis of Ledinegg flow instability in natural circulation at supercritical pressure

In order to study the effect of rolling motion on flow instability of parallel rectangular channels of natural circulation, the natural circulation reactor simulation system is used for physical prototype. And theory analysis model of parallel rectangular channels of natural circulation system under rolling motion is established and coded by Fortran. The results of the program are verified to the experiments, and the results are in good agreement. The flow instability boundaries of different pressure under static and rolling motion are calculated respectively. The results show that: 1) under static condition, with the increase of the pressure, the instability boundary line changes, and the system becomes more stable; 2) under rolling conditions, the heating power of instability boundary decreases comparing to the stable conditions. The instability occurs earlier; 3) the stability of the system decreases with the increasing of rolling amplitude and frequency.

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Experimental Study on Two-Phase Natural Circulation Flow Instability in Rod Bundle Channel Under Low Pressure Condition

Volume 6A: Thermal-Hydraulics and Safety Analyses ◽

10.1115/icone26-81225 ◽

2018 ◽

Author(s):

Kun Cheng ◽

Sichao Tan ◽

Zheng Liu ◽

Tao Meng

Keyword(s):

Flow Instability ◽

Natural Circulation ◽

Oscillation Amplitude ◽

Density Wave ◽

Low Pressure ◽

Heating Power ◽

Pressure Condition ◽

Two Phase ◽

Rod Bundle ◽

System Pressure

An experimental investigation was conducted in a natural circulation (NC) loop to study the characteristics of two-phase flow instability under low pressure condition. A 3 × 3 rod bundle channel was used as the test section. The effects of heating power, inlet subcooling degree and system pressure on the two-phase NC flow instability types and stable boundaries were studied. The experimental results show that three typical flow conditions can occur in rod bundle channel under NC condition, which are single-phase NC flow, subcooled boiling NC flow oscillation and density wave oscillations (DWO). The oscillation amplitude and period of DWO can be enlarged by increasing the heat flux. Increasing the inlet subcooling degree can increase the marginal heating power of flow instability in NC system. The occurrence of DWO can be suppressed by increasing the system pressure. The flow instability boundary presented by the subcooling number and phase change number was also obtained in present work.

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Influences of tube wall on the heat transfer and flow instability of various supercritical pressure fluids in a vertical tube

Applied Thermal Engineering ◽

10.1016/j.applthermaleng.2018.10.024 ◽

2019 ◽

Vol 147 ◽

pp. 242-250 ◽

Cited By ~ 4

Author(s):

Zhen Zhang ◽

Chenru Zhao ◽

Xingtuan Yang ◽

Peixue Jiang ◽

Shengyao Jiang ◽

...

Keyword(s):

Heat Transfer ◽

Flow Instability ◽

Tube Wall ◽

Vertical Tube ◽

Supercritical Pressure

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Numerical Simulations on Supercritical Water Flow Instability

Volume 2A: Thermal Hydraulics ◽

10.1115/icone22-30171 ◽

2014 ◽

Author(s):

Jingjing Li ◽

Tao Zhou ◽

Mingqiang Song ◽

Yanping Huang

Keyword(s):

Numerical Simulations ◽

Water Flow ◽

Mass Flow ◽

Supercritical Water ◽

Flow Instability ◽

Natural Circulation ◽

Heating Power ◽

Circulation Loop ◽

Natural Circulation Loop ◽

Parallel Channels

3-D simulation of supercritical water flow instability in parallel channels and a natural circulation loop are presented. Results are obtained for various heating powers. The results show that, in the natural circulation loop the steady state mass flow will firstly increase with the heating power and then decrease. And mass flow grows with the growing of the inlet temperature, decreases with the growing of system pressure. Under a large heat flux, the parallel channels will experience the flow instability of out phase mass flow oscillation. And the oscillation amplitude will grow with the growing of heating power. At last, the numerical simulations are validated by B.T. Swapnalee’s experience formula.

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Experimental research and theoretical analysis of flow instability in supercritical carbon dioxide natural circulation loop

Applied Energy ◽

10.1016/j.apenergy.2017.08.132 ◽

2017 ◽

Vol 205 ◽

pp. 813-821 ◽

Cited By ~ 6

Author(s):

Guangxu Liu ◽

Yanping Huang ◽

Junfeng Wang ◽

Fa Lv ◽

Shenghui Liu

Keyword(s):

Carbon Dioxide ◽

Supercritical Carbon Dioxide ◽

Theoretical Analysis ◽

Experimental Research ◽

Flow Instability ◽

Natural Circulation ◽

Circulation Loop ◽

Natural Circulation Loop ◽

Supercritical Carbon

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Non-Linear Time Series Analysis of the Infuence of Rolling Motion on Natural Circulation System

18th International Conference on Nuclear Engineering: Volume 4, Parts A and B ◽

10.1115/icone18-29351 ◽

2010 ◽

Author(s):

Wenchao Zhang ◽

Sichao Tan ◽

Puzhen Gao

Keyword(s):

Experimental Data ◽

Time Series ◽

Time Series Analysis ◽

Two Phase Flow ◽

Flow Instability ◽

Natural Circulation ◽

Rolling Motion ◽

Phase Flow ◽

Two Phase ◽

Series Analysis

Two-phase natural circulation flow instability under rolling motion condition was studied experimentally and theoretically. Experimental data were analyzed with nonlinear time series analysis methods. The embedding dimension, correlation dimension and K2 entropy were determined based on phase space reconstruction theory and G-P method. The maximal Lyapunov exponent was calculated according to the methods of small data sets. The nonlinear features of the two phase flow instability under rolling motion were analyzed with the results of geometric invariants coupling with the experimental data. The results indicated that rolling motion strengthened the nonlinear characteristics of two phase flow instability. Some typical nonlinear phenomena such as period-doubling bifurcations and chaotic oscillations were found in different cases.

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An Experiment of Natural Circulation Flow and Heat Transfer With Supercritical Water in Parallel Channels

Journal of Nuclear Engineering and Radiation Science ◽

10.1115/1.4032779 ◽

2016 ◽

Vol 2 (3) ◽

Author(s):

Yuzhou Chen ◽

Chunsheng Yang ◽

Minfu Zhao ◽

Keming Bi ◽

Kaiwen Du

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Flow Rate ◽

Supercritical Water ◽

Dynamic Instability ◽

Flow Instability ◽

Natural Circulation ◽

Transfer Coefficients ◽

Heat Transfer Coefficients ◽

Parallel Channels

An experiment of natural circulation of supercritical water in parallel channels was performed in bare tubes of inner diameter 7.98 mm and heated length 1.3 m, covering the ranges of pressure of 24.7–25.5 MPa, mass flux of 400–1000 kg/m2 s, and heat flux of up to 1.83 MW/m2. When the heat flux reached 1.12 MW/m2, the outlet water temperature jumped from 325°C to 360°C, associated with a decrease in the flow rate and an initiation of dynamic instability. When the heat flux exceeded 1.39 MW/m2, the flow instability was stronger, and the flow rate increased in one channel and decreased in another one. Until the heat flux reached 1.61 MW/m2, the outlet water temperatures of two channels reached the pseudocritical point, and the flow rates of two channels tended to close each other. The experiment with a single heated channel was also performed for comparison. The measurements on the heat-transfer coefficients (HTCs) were compared to the calculations by the Bishop et al., Jackson’s, and Mokry et al. correlations, showing different agreements within various conditions.

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