Modeling analyses of two-phase flow instabilities for straight and helical tubes in nuclear power plants

Heater drain systems in fossil and nuclear power plants have proven to be among the most complex systems to design due to the occurrence of two–phase flow phenomena. The overall performance of heater drain systems directly relates to proper sizing and design of the piping and control valves. Proper sizing is highly dependent upon accurate and conservative calculation of two-phase flow pressure losses. This paper outlines the various options of solution methods available to the engineer and details one possible method which is simple, yet adequate, and based on the homogeneous equilibrium model (HEM) for two phase flow for calculation of heater drain system performance. General comparisons are made to the more complex multi-fluid models, flow regime considerations, and non-equilibrium models.

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Study on Two-Phase Flow Instabilities in Straight and Helical Tubes

Proceedings of The 20th Pacific Basin Nuclear Conference ◽

10.1007/978-981-10-2314-9_80 ◽

2017 ◽

pp. 893-903

Author(s):

Ruiting Dong ◽

Fenglei Niu ◽

Yuan Zhou

Keyword(s):

Two Phase Flow ◽

Flow Instabilities ◽

Phase Flow ◽

Two Phase ◽

Helical Tubes

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Periodic Oscillations in Natural Circulation Boiling System

Volume 6: Thermal-Hydraulics ◽

10.1115/icone25-66689 ◽

2017 ◽

Author(s):

Xianbing Chen ◽

Puzhen Gao ◽

Qiang Wang ◽

Yinxing Zhang ◽

Jiawei Liu

Keyword(s):

Mass Flux ◽

Nuclear Power ◽

Power Plants ◽

Two Phase Flow ◽

Flow Instability ◽

Natural Circulation ◽

Flow Reversal ◽

Phase Flow ◽

Two Phase ◽

Periodic Oscillations

Natural circulation has been widely used in some evolutionary and innovative nuclear power plants. Natural circulation systems are susceptible to flow instabilities which are undesirable in the nuclear power devices. An experimentally investigation of two phase flow instability in up-flow boing channel under natural circulation is presented in this paper. Flow instability with and without flow reversal have been found. A pulse signal of water temperature at the inlet of the test section can be detected when the channel suffers from flow reversal. Single phase and two phase flow alternate in the channel regardless of the occurrence of flow reversal. Periodic oscillations with multiple high-order harmonic waves are confirmed by applying Fast Fourier Transform to the time traces of flow rates. Period of flow instability which is the reciprocal of the frequency with the largest amplitude in the amplitude-frequency plane are obtained. Period of flow oscillation presents a nonlinear change with the increase of mass flux. Period of flow instability increases rapidly with the increase of mass flux and decreases slowly when it reaches the maximum value.

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Classification of Two-Phase Flow Patterns by Ultrasonic Sensing

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.4007555 ◽

2012 ◽

Vol 135 (2) ◽

Cited By ~ 6

Author(s):

Devesh K. Jha ◽

Asok Ray ◽

Kushal Mukherjee ◽

Subhadeep Chakraborty

Keyword(s):

Pattern Classification ◽

Nuclear Power ◽

Power Plants ◽

Two Phase Flow ◽

Flow Patterns ◽

Industrial Applications ◽

Phase Flow ◽

Two Phase ◽

Ultrasonic Sensing

This paper presents a methodology for classification of two-phase flow patterns in fluid systems, which takes the measurements of an in situ ultrasonic sensor as inputs. In contrast to the common practice of having an array of ultrasonic detectors, the underlying algorithm requires only a single sensor hardware in combination with an integrated software of signal conditioning, feature extraction, and pattern classification. The proposed method is noninvasive and can be implemented in a variety of industrial applications (e.g., petrochemical processes and nuclear power plants). This concept of flow pattern classification is experimentally validated on a laboratory test apparatus.

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