An experimental study of the size effect on adiabatic gas-liquid two-phase flow patterns and void fraction in microchannels

Experiments were performed to obtain, analyze and clarify the mean void fraction, the mean liquid holdup, and the liquid slug velocity and the air-water two-phase flow patterns in horizontal rectangular microchannels, with the dimensions equal to 1.0 mm width × 0.1 mm depth, and 1.0 mm width × 0.2 mm depth, respectively. The flow patterns such as bubble flow, slug flow and annular flow were observed. The microchannel data showed similar data patterns compared to those in minichannels with the width of 1∼10mm and the depth of 1mm which we had previously reported on. However, in a 1.0 × 0.1 mm microchannel, the mean holdup and the base film thickness in annular flow showed larger values because the effects of liquid viscosity and surface tension on the holdup and void fraction dominate. The remarkable flow characteristics of rivulet flow and the flow with a partial dry out of the channel inner wall were observed in slug flow and annular flow patterns in the microchannel of 0.1 mm depth.

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Experimental study on vertically upward steam-water two-phase flow patterns in narrow rectangular channel

Nuclear Engineering and Technology ◽

10.1016/j.net.2020.06.003 ◽

2021 ◽

Vol 53 (1) ◽

pp. 61-68

Author(s):

Jiancheng Zhou ◽

Tianzhou Ye ◽

Dalin Zhang ◽

Gongle Song ◽

Rulei Sun ◽

...

Keyword(s):

Experimental Study ◽

Two Phase Flow ◽

Rectangular Channel ◽

Flow Patterns ◽

Phase Flow ◽

Two Phase

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Experimental Study on Interfacial Area Transport of Two-Phase Flow under Vibration Conditions

Science and Technology of Nuclear Installations ◽

10.1155/2017/5809541 ◽

2017 ◽

Vol 2017 ◽

pp. 1-13 ◽

Cited By ~ 1

Author(s):

Xiu Xiao ◽

Qingzi Zhu ◽

Shao-Wen Chen ◽

Mamoru Ishii ◽

Yajun Zhang ◽

...

Keyword(s):

Experimental Study ◽

Void Fraction ◽

Vibration Frequency ◽

Two Phase Flow ◽

Bubble Diameter ◽

Interfacial Area ◽

Phase Flow ◽

Two Phase ◽

Vibration Direction ◽

Local Parameters

An experimental study on air-water two-phase flow under vibration condition has been conducted using double-sensor conductivity probe. The test section is an annular geometry with hydraulic diameter of 19.1 mm. The vibration frequency ranges from 0.47 Hz to 2.47 Hz. Local measurements of void fraction, interfacial area concentration (IAC), and Sauter mean diameter have been performed along one radius in the vibration direction. The result shows that local parameters fluctuate continuously around the base values in the vibration cycle. Additional bubble force due to inertia is used to explain lateral bubble motions. The fluctuation amplitudes of local void fraction and IAC increase significantly with vibration frequency. The radial distribution of local parameters at the maximum vibration displacement is specifically analyzed. In the void fraction and IAC profiles, the peak near the inner wall is weakened or even disappearing and a strong peak skewed to outer wall is gradually observed with the increase of vibration frequency. The nondimensional peak void fraction can reach a maximum of 49% and the mean relative variation of local void fraction can increase to more than 29% as the vibration frequency increases to 2.47 Hz. But the increase of vibration frequency does not bring significant change to bubble diameter.

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An Experimental Study on Air-Water Two-Phase Flow Patterns in Pebble Beds

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4000337 ◽

2010 ◽

Vol 132 (4) ◽

Cited By ~ 1

Author(s):

Bai Bofeng ◽

Liu Maolong ◽

Su Wang ◽

Zhang Xiaojie

Keyword(s):

Experimental Study ◽

Flow Pattern ◽

Test Section ◽

Slug Flow ◽

Annular Flow ◽

Two Phase Flow ◽

Flow Patterns ◽

Phase Flow ◽

Two Phase ◽

Flow Pattern Transition

An experimental study was conducted on the air-water two-phase flow patterns in the bed of rectangular cross sections containing spheres of regular distribution. Three kinds of glass spheres with different diameters (3 mm, 6 mm, and 8 mm) were used for the establishment of the test section. By means of visual observations of the two-phase flow through the test section, it was discovered that five different flow patterns occurred within the experimental parameter ranges, namely, bubbly flow, bubbly-slug flow, slug flow, slug-annular flow, and annular flow. A correlation for the bubble and slug diameter in the packed beds was proposed, which was an extended expression of the Tung/Dhir model, Jamialahmadi’s model, and Schmidt’s model. Three correlations were proposed to calculate the void friction of the flow pattern transition in bubble flow, slug flow, and annular flow based on the bubble model in the pore region. The experimental result showed that the modified Tung and Dhir model of the flow pattern transition was in better agreement with the experimental data compared with Tung and Dhir’s model.

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Evaluation of Void Fraction Correlations for the Statistical and Numerical Analysis of Two-Phase Flows Inside Producing Geothermal Wells

Volume 10: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A, B, and C ◽

10.1115/imece2008-68926 ◽

2008 ◽

Author(s):

A. A´lvarez del Castillo ◽

E. Santoyo ◽

O. Garci´a-Valladares ◽

P. Sa´nchez-Upton

Keyword(s):

Void Fraction ◽

Two Phase Flow ◽

Flow Patterns ◽

Temperature Gradients ◽

Production Performance ◽

Phase Flow ◽

Two Phase ◽

Precise Knowledge ◽

Geothermal Wells ◽

Gas Void Fraction

The modeling of heat and fluid flow inside two-phase geothermal wells is a vital task required for the study of the production performance. Gas void fraction is one of the crucial parameters required for a better prediction of pressure and temperature gradients in two-phase geothermal wells. This parameter affects the correct matching between simulated and measured data. Modeling of two-phase flow inside wells is complex because two phases exist concurrently (exhibiting various flow patterns that depend on their relative concentrations, the pipe geometry, and the mass flowrate). A reliable modeling requires the precise knowledge of the two-phase flow patterns (including their transitions and some flow parameters). In this work, ten empirical correlations were used to estimate the gas void fraction in vertical-inclined pipes, and to evaluate their effect on the prediction of two-phase flow characteristics of some Mexican geothermal wells. High quality downhole pressure/ temperature logs collected from four producing geothermal wells were studied [Los Azufres, Mich. (Az-18); Los Humeros, Pue. (H-1), and Cerro Prieto, B.C. (M-90 and M-201)]. The pressure/ temperature gradients were simulated using an improved version of the wellbore simulator GEOPOZO, and the gas void fraction correlations. The simulated results were statistically compared with measured field data.

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Experimental study on the void fraction of air-water two-phase flow in a horizontal circular minichannel

10.1063/1.4949302 ◽

2016 ◽

Cited By ~ 3

Author(s):

Sudarja ◽

Indarto ◽

Deendarlianto ◽

Aqli Haq

Keyword(s):

Experimental Study ◽

Void Fraction ◽

Two Phase Flow ◽

Phase Flow ◽

Two Phase

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Two-Phase Flow-Induced Forces on Piping in Vertical Upward Flow: Excitation Mechanisms and Correlation Models

Journal of Pressure Vessel Technology ◽

10.1115/1.4024210 ◽

2013 ◽

Vol 135 (3) ◽

Cited By ~ 9

Author(s):

M. Giraudeau ◽

N. W. Mureithi ◽

M. J. Pettigrew

Keyword(s):

Void Fraction ◽

Two Phase Flow ◽

Low Frequency ◽

Flow Patterns ◽

Large Momentum ◽

Phase Flow ◽

Upward Flow ◽

Two Phase ◽

Correlation Models ◽

Wide Range

Momentum variation in two-phase flow generates significant low frequency forces, capable of producing unwanted and destructive vibrations in nuclear or petroleum industries. Two-phase flow-induced forces in piping were previously studied over a range of diameters from 6 mm to 70 mm in different piping element geometries, such as elbows, U-bends, and tees. Dimensionless models were then developed to estimate the rms forces and generate vibration excitation force spectra. It was found that slug flow generates the largest forces due to the large momentum variation between Taylor bubbles and slugs. The present study was conducted with a 52 mm diameter U-bend tube carrying a vertical upward flow. Two-phase flow-induced forces were measured. In addition, two-phase flow parameters, such as the local void fraction, bubble size and velocity, and slug frequency were studied to understand the relationship between the force spectra and the two-phase flow patterns. A new two-phase flow pattern map, based on existing transition models and validated using our own local void fraction measurements and force spectra, is proposed. This paper also presents a comparison of the present dimensionless forces with those of previous studies, thus covers a wide range of geometries and Weber numbers. Finally, a dimensionless spectrum is proposed to correlate forces with large momentum variations observed for certain flow patterns.

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