scholarly journals Detection of Two-Phase Flow Patterns in a Vertical Minichannel Using the Recurrence Quantification Analysis

2015 ◽  
Vol 9 (2) ◽  
pp. 99-104
Author(s):  
Romuald Mosdorf ◽  
Grzegorz Górski
Keyword(s):  
Time Series ◽  
Two Phase Flow ◽  
Bubbly Flow ◽  
Flow Patterns ◽  
Recurrence Quantification Analysis ◽  
Phase Flow ◽  
Two Phase ◽  
Signal Characteristics ◽  
Recurrence Quantification ◽  
Quantification Analysis

Abstract The two-phase flow (water-air) occurring in square minichannel (3x3 mm) has been analysed. In the minichannel it has been observed: bubbly flow, flow of confined bubbles, flow of elongated bubbles, slug flow and semi-annular flow. The time series recorded by laser-phototransistor sensor was analysed using the recurrence quantification analysis. The two coefficients:Recurrence rate (RR) and Determinism (DET) have been used for identification of differences between the dynamics of two-phase flow patterns. The algorithm which has been used normalizes the analysed time series before calculating the recurrence plots.Therefore in analysis the quantitative signal characteristicswas neglected. Despite of the neglect of quantitative signal characteristics the analysis of its dynamics (chart of DET vs. RR) allows to identify the two-phase flow patterns. This confirms that this type of analysis can be used to identify the two-phase flow patterns in minichannels.

Flow Boiling Visualization of R-134a in a Vertical Channel of Small Diameter

2007 ◽  
Author(s):  
Claudi Marti´n-Callizo ◽  
Bjo¨rn Palm ◽  
Wahib Owhaib ◽  
Rashid Ali
Keyword(s):  
Flow Pattern ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Bubbly Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase ◽  
R 134A ◽  
Heated Length

The present work reports on flow boiling visualization of refrigerant R-134a in a vertical circular channel with internal diameter of 1.33 mm and 235 mm in heated length. Quartz tube with a homogeneous ITO-coating is used allowing heating and simultaneous visualization. Flow patterns have been observed along the heated length with the aid of a digital camera with close-up lenses. From the flow boiling visualization, seven distinct two-phase flow patterns have been observed: Isolated bubbly flow, confined bubbly flow, slug flow, churn flow, slug-annular flow, annular flow, and mist flow. Two-phase flow pattern observations are presented in the form of flow pattern maps. Finally, the experimental flow pattern map is compared to models developed for conventional sizes as well as to a microscale map for air-water mixtures available in the literature, showing a large discrepancy.

scholarly journals Boiling Flow Pattern Identification Using a Self-Organizing Map

2020 ◽  
Vol 10 (8) ◽  
pp. 2792
Author(s):  
Iwona Zaborowska ◽  
Hubert Grzybowski ◽  
Romuald Mosdorf
Keyword(s):  
Pressure Drop ◽  
Flow Patterns ◽  
Recurrence Quantification Analysis ◽  
Bubble Flow ◽  
Self Organizing Map ◽  
Two Phase ◽  
Recurrence Quantification ◽  
Quantification Analysis ◽  
Flow Pattern Identification ◽  
Self Organizing

In the paper, a self-organizing map combined with the recurrence quantification analysis was used to identify flow boiling patterns in a circular horizontal minichannel with an inner diameter of 1 mm. The dynamics of the pressure drop during density-wave oscillations in a single pressure drop oscillations cycle were considered. It has been shown that the proposed algorithm allows us to distinguish five types of non-stationary two-phase flow patterns, such as bubble flow, confined bubble flow, wavy annular flow, liquid flow, and slug flow. The flow pattern identification was confirmed by images obtained using a high-speed camera. Taking into consideration the oscillations between identified two-phase flow patterns, the four boiling regimes during a single cycle of the long-period pressure drop oscillations are classified. The obtained results show that the proposed combination of recurrence quantification analysis (RQA) and a self-organizing map (SOM) in the paper can be used to analyze changes in flow patterns in non-stationary boiling. It seems that the use of more complex algorithms of neural networks and their learning process can lead to the automation of the process of identifying boiling regimes in minichannel heat exchangers.

Distinguish the Pattern of Two-Phase Flow with the Technology of Acoustic Emission

2013 ◽  
Vol 816-817 ◽  
pp. 502-505
Author(s):  
Li De Fang ◽  
Yao Zhang ◽  
Wan Ling Zhang ◽  
Qing He ◽  
Yu Jiao Liang
Keyword(s):  
Acoustic Emission ◽  
Two Phase Flow ◽  
New Technology ◽  
Bubbly Flow ◽  
Flow Patterns ◽  
New Method ◽  
Good Effect ◽  
Phase Flow ◽  
Two Phase ◽  
Horizontal Pipe

This paper has propose a new method (acoustic emission) to distinguish the pattern of gas-liquid two-phase flow in the horizontal pipe. The signals which got from the probe when multiphase flow pattern changes in the pipe and the four probe installed on the different position. Through the analysis of time domination, energy of wavelet, collected the signal features and shows there has a significant differences among the three typical flow patterns (bubbly flow, stratified flow, annular flow). Energy of wavelet can clearly represents the signal strength. This paper found that the acoustic emission as a new method to distinguish flow patterns have good effect can as a new technology for the study of gas-liquid two-phase.

scholarly journals Complex networks from multivariate time series for characterizing nonlinear dynamics of two-phase flow patterns

2012 ◽  
Vol 61 (12) ◽  
pp. 120510
Author(s):  
Gao Zhong-Ke ◽  
Jin Ning-De ◽  
Yang Dan ◽  
Zhai Lu-Sheng ◽  
Du Meng
Keyword(s):  
Nonlinear Dynamics ◽  
Time Series ◽  
Complex Networks ◽  
Two Phase Flow ◽  
Multivariate Time Series ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase

Co-Current Air-Water Two Phase Flow Patterns in Horizontal and Vertical Circular Tube Under Various Inlet Conditions

2011 ◽  
Author(s):  
S. Zeguai ◽  
S. Chikh ◽  
O. Rahli ◽  
L. Tadrist
Keyword(s):  
Annular Flow ◽  
Two Phase Flow ◽  
Bubbly Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Transition Flow ◽  
Two Phase ◽  
Experimental Apparatus ◽  
Inner Diameter ◽  
Inlet Conditions

An experimental apparatus is setup to analyze a co-current air-water two phase flow in a 3 mm inner diameter tube with horizontal and vertical orientations. Air is axially injected through a nozzle of 260 μm of inner diameter. Air and water flow rates are accurately controlled at the inlet, covering a range of apparent velocities JL = 0.00118 to 0.0786 m/s, JG = 0.002 to 3.538 m/s for the horizontal tube and JL = 0.00078 to 0.0589 m/s, JG = 0.003 to 3.538 m/s for the upward flow. A fast camera with 250 fps is utilized to visualize the flow patterns. The experiments showed that the flow structures are very sensitive to inlet conditions. Within the covered range of velocities, several flow patterns were observed, namely bubbly flow, bubbly-slug transition flow, slug flow, slug-annular transition flow, annular flow, wavy annular flow and annular flow with dry zones. In the bubbly flow regime, a particular bubbly helical flow is observed before the dispersed bubbly flow.

Flow Boiling Visualization of R-134a in a Vertical Channel of Small Diameter

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Claudi Martín-Callizo ◽  
Björn Palm ◽  
Wahib Owhaib ◽  
Rashid Ali
Keyword(s):  
Flow Pattern ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Bubbly Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase ◽  
R 134A ◽  
Heated Length

The present work reports on flow boiling visualization of refrigerant R-134a in a vertical circular channel with an internal diameter of 1.33 mm and 235 mm in heated length. A quartz tube with a homogeneous Indium Tin Oxide coating is used to allow heating and simultaneous visualization. Flow patterns have been observed along the heated length with the aid of high-speed complementary metal oxide semiconductor (CMOS) digital camera. From the flow boiling visualization, seven distinct two-phase flow patterns have been observed: isolated bubbly flow, confined bubbly flow, slug flow, churn flow, slug-annular flow, annular flow, and mist flow. Two-phase flow pattern observations are presented in the form of flow pattern maps. The effects of the saturation temperature and the inlet subcooling degree on the two-phase flow pattern transitions are elucidated. Finally, the experimental flow pattern map is compared with models developed for conventional sizes as well as to a microscale map for air-water mixtures available in literature, showing a large discrepancy.

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