Development of a Capacitance Based Void Fraction Sensor for Two-Phase Flow Measurements

2013 ◽  
Author(s):  
Rodward L. Hewlin ◽  
John P. Kizito
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Full Range ◽  
Working Fluid ◽  
Phase Flow ◽  
Calibration Data ◽  
Two Phase ◽  
Flow Measurements ◽  
Static Calibration ◽  
Wide Range

The aim of this paper was to develop a capacitance based sensor capable of measuring void fraction in a continuous two-phase flow field. The design methodology and operation of the capacitance based void fraction sensor is discussed. Two designs of capacitance void fraction sensors were developed and tested. Some of the problems associated with the first were identified and a new sensor electrode configuration was developed which presented a more sensitive and repeatable response. Data was collected covering a wide range of void fraction measurements ranging from 0 to 1 for water as the working fluid. Calibration of the sensor required that the air gap or void capacitance (dry signal) be measured followed by an increase in liquid levels (wet signal) to obtain a range of void fraction measurements for static calibration. The static calibration data obtained was nonlinear for the full range of void fraction measurements for water. This paper covers the design requirements, calibration procedure and static calibration data obtained for the developed sensor, and dynamic void fraction data measurements. The sensor was tested in both a horizontal and vertical orientation and proved to be orientation insensitive. The experimental results are promising for water and verify successful operation for measuring void fraction in continuous two-phase flows.

Axial Development of Vertical Upward Bubbly Flow in a Minipipe

2005 ◽  
Author(s):  
Tatsuya Hazuku ◽  
Naohisa Tamura ◽  
Norihiro Fukamachi ◽  
Tomoji Takamasa ◽  
Takashi Hibiki ◽  
...  
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Constitutive Relations ◽  
Interfacial Area ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Measurements ◽  
Local Flow ◽  
Interfacial Area Concentration ◽  
Drift Flux Model

Accurate prediction of the interfacial area concentration is essential to successful development of the interfacial transfer terms in the two-fluid model. Mechanistic modeling of the interfacial area concentration entirely relies on accurate local flow measurements over extensive flow conditions and channel geometries. From this point of view, accurate measurements of flow parameters such as void fraction, interfacial area concentration, gas velocity, bubble Sauter mean diameter, and bubble number density were performed by the image processing method at five axial locations in vertical upward bubbly flows using a 1.02 mm-diameter pipe. The frictional pressure loss was also measured by a differential pressure cell. In the experiment, the superficial liquid velocity and the void fraction ranged from 1.02 m/s to 4.89 m/s and from 0.980% to 24.6%, respectively. The obtained data give near complete information on the time-averaged local hydrodynamic parameters of two-phase flow. These data can be used for the development of reliable constitutive relations which reflect the true transfer mechanisms in two-phase flow. As the first step to understand the flow characteristics in mini-channels, the applicability of the existing drift-flux model, interfacial area correlation, and frictional pressure correlation was examined by the data obtained in the mini-channel.

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

2013 ◽  
Vol 135 (3) ◽  
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.

scholarly journals Two-phase flow measurements at high void fraction by a Venturi meter

2014 ◽  
Vol 77 ◽  
pp. 167-175 ◽  
Author(s):  
Grazia Monni ◽  
Mario De Salve ◽  
Bruno Panella
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Measurements

Correlation between Void Fraction and Two-Phase Flow Pattern Air-Water with Low Viscosity in Mini Channel with Slope 30 Degrees

2020 ◽  
Vol 846 ◽  
pp. 289-295
Author(s):  
Sukamta ◽  
Sudarja
Keyword(s):  
Void Fraction ◽  
High Speed ◽  
Two Phase Flow ◽  
Fluid Velocity ◽  
Flow Patterns ◽  
Superficial Velocity ◽  
Working Fluid ◽  
Phase Flow ◽  
Two Phase ◽  
Void Fractions

Two-phase flow has been used in so many industrial processes, such as boilers, reactors, heat exchangers, geothermal and others. Some parameters which need to be studied include flow patterns, void fractions, and pressure changes. Research on void fractions aims to determine the composition of the gas and liquid phases that will affect the nature and value of the flow property. The purpose of this study is to find out the characteristics of the void fraction of various patterns that occurs and to determine the characteristics of the velocity, length, and frequency of bubbly and plug. Data acquisition was used to convert the data from analog to digital so that it can be recorded, stored, processed, and analyzed. High-speed camera Nikon type J4 was used to record the flow. The condition of the study was adiabatic with variation of superficial gas velocity (JG), superficial fluid velocity (JL), and also working fluid. To determine the void fraction by using the digital image processing method. The results of the study found that the flow patterns which occurred in this study were bubbly, plug, annular, slug-annular and churn flows. It also showed that the void fraction value is determined by the superficial velocity of the liquid and air. The higher the superficial velocity of the air, the lower the void fraction value.

On the Damping in Tube Arrays Subjected to Two-Phase Cross-Flow

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
J. E. Moran ◽  
D. S. Weaver
Keyword(s):  
Flow Regime ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Cross Flow ◽  
Working Fluid ◽  
Exponential Fitting ◽  
Phase Flow ◽  
Two Phase ◽  
Tube Arrays ◽  
Half Power

An experimental study was conducted to investigate the mechanism of damping in tube arrays subjected to two-phase cross-flow, mainly focusing on the influence of void fraction and flow regime. The model tube bundle had a parallel-triangular configuration, with a pitch ratio of 1.49. The two-phase flow loop used in this research utilized Refrigerant 11 as the working fluid, which better models steam-water than air-water mixtures in terms of vapour-liquid mass ratio as well as permitting phase changes due to pressure fluctuations. The void fraction was measured using a gamma densitometer, introducing an improvement over the homogeneous equilibrium model (HEM). Three different damping measurement methodologies were implemented and compared in order to obtain a more reliable damping estimate: the traditionally used half-power bandwidth, the logarithmic decrement and an exponential fitting to the tube decay response. The experiments showed that the half-power bandwidth produces higher damping values than the other two methods, due to the tube frequency shifting triggered by fluctuations in the added mass and coupling between the tubes, which depend on void fraction and flow regime. The exponential fitting proved to be the more consistent and reliable approach to estimating damping. A dimensional analysis was carried out to investigate the relationship between damping and two-phase flow related parameters. As a result, the inclusion of surface tension in the form of the capillary number appears to be useful when combined with the two-phase component of the damping ratio (interfacial damping). A strong dependence of damping on flow regime was observed when plotting the interfacial damping versus the void fraction, introducing an improvement over the previous results obtained by normalizing the two-phase damping, which does not exhibit this behavior.

Velocities Effects on the Void Fraction Distribution in a Vertical Gas-Liquid Two-Phase Flow Channel

2014 ◽  
Vol 889-890 ◽  
pp. 369-373
Author(s):  
Mohd Zamri Zainon ◽  
Mohd Ardan Zubir ◽  
Rahizar Ramli
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Flow Channel ◽  
Phase Flow ◽  
Flow Loop ◽  
Two Phase ◽  
Void Fractions ◽  
Conductance Method ◽  
Wide Range ◽  
Fraction Distribution

Measurement of void fraction in a vertically arranged gas-liquid two-phase flow channel has been conducted for wide range of flow conditions using a specially developed sensor based on electric conductance method. The effects of velocities of both phases were examined with variety of combinations using an industrial scale two-phase flow loop. The results show that at a constant rate of liquid superficial velocities the void fractions increases with the increasing gas superficial velocities and at higher velocities of liquid phase, the value of void fraction becoming lower. The average void fractions were also compared with other scholars results.

Measurement of Void Fraction and Pressure Drop of Air-Oil Two-Phase Flow in Horizontal Pipes

2004 ◽  
Vol 126 (1) ◽  
pp. 107-118 ◽  
Author(s):  
J. L. Pawloski ◽  
C. Y. Ching ◽  
M. Shoukri
Keyword(s):  
Pressure Drop ◽  
Flow Regime ◽  
Void Fraction ◽  
High Speed ◽  
Two Phase Flow ◽  
Flow Regimes ◽  
Phase Flow ◽  
Two Phase ◽  
Wide Range ◽  
Flow Regime Maps

The void fractions, flow regimes, and pressure drop of air-oil two-phase flow in a half-inch diameter pipe over a wide range of test conditions have been investigated. The flow regimes were identified with the aid of a 1000 frames per second high-speed camera. A capacitance sensor for instantaneous void fraction measurements was developed. The mean and probability density function of the instantaneous void fraction signal can be used to effectively identify the different flow regimes. The current flow regime data show significant differences in the transitional boundaries of the existing flow regime maps. Property correction factors for the flow regime maps are recommended. The pressure drop measurements were compared to the predictions from four existing two-phase flow pressure drop models. Though some of the models performed better for certain flow regimes, none of the models were found to give accurate results over the entire range of flow regimes.

Axial Development of Gas-Liquid Two-Phase Flow in Mini-Channels

2006 ◽  
Author(s):  
Junichi Uematsu ◽  
Yoshinori Hirose ◽  
Tatsuya Hazuku ◽  
Tomoji Takamasa ◽  
Takashi Hibiki
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Interfacial Area ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Measurements ◽  
Local Flow ◽  
Interfacial Area Concentration ◽  
Drift Flux Model ◽  
Mini Channels

Accurate prediction of the interfacial area concentration is essential to successful development of the interfacial transfer terms in the two-fluid model. Mechanistic modeling of the interfacial area concentration entirely relies on accurate local flow measurements over extensive flow conditions and channel geometries. From this point of view, accurate measurements of flow parameters such as void fraction, interfacial area concentration, gas velocity, bubble Sauter mean diameter, and bubble number density were performed by the image processing method at five axial locations in vertical upward bubbly flows using 1.02 and 0.55 mm-diameter pipes. The frictional pressure loss was also measured by a differential pressure cell. In the experiment, the superficial liquid velocity and the void fraction ranged from 0.475 m/s to 4.89 m/s and from 0.980% to 28.6%, respectively. The obtained data give near complete information on the time-averaged local hydrodynamic parameters of two-phase flow. These data can be used for the development of reliable constitutive relations which reflect the true transfer mechanisms in two-phase flow. As the first step to understand the flow characteristics in mini-channels, the applicability of the existing drift-flux model, interfacial area correlation, and frictional pressure correlation was examined by the data obtained in the mini-channels.

scholarly journals Influence of Bubble Deformation on the Signal Characteristics Generated Using an Optical Fiber Gas–Liquid Two-Phase Flow Sensor

Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 7338
Author(s):  
Yu Ma ◽  
Yangrui Zhang ◽  
Song Li ◽  
Weimin Sun ◽  
Elfed Lewis
Keyword(s):  
Optical Fiber ◽  
Chemical Engineering ◽  
Two Phase Flow ◽  
Three Dimensional ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Measurements ◽  
Fiber Probe ◽  
Bubble Deformation ◽  
Wide Range

The use of optical fiber probe in two-phase flow measurements is very frequently encountered, especially in the applications of chemical engineering and petroleum industries. In this work, the influence of bubble piercing signals caused by bubble deformation is studied experimentally using a laboratory-prepared wedge-shaped fiber probe in a lab-scale gas–liquid flow generator. A three-dimensional simulation model is established to study the influence of bubble deformation on the piercing signals. A theoretical analysis of the characteristics of the pre-signal influenced by the bubble deformations is undertaken for a wide range of different modeled bubble shapes. Combining the experimental and simulation results, a promising analytical method to estimate the bubble shapes by analyzing the characteristics of pre-signals is proposed. The results of this investigation demonstrate that it is possible to estimate the bubble shapes before the fiber probe contacts the bubble surface. The method developed in this investigation is therefore highly promising for reducing errors caused by deformation during the probe piercing process.

scholarly journals THE INVESTIGATION OF VOID FRACTION OF TWO-PHASE FLOW AIR-WATER AND GLYCERINE (0-30%) IN THE CAPILLARY PIPE WITH SLOPE OF 50 TO HORIZONTAL POSITION

2019 ◽  
Vol 20 (1) ◽  
pp. 8-17
Author(s):  
S Sukamta ◽  
Aldi Rahadian Ilham ◽  
S Sudarja
Keyword(s):  
Flow Pattern ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Bubbly Flow ◽  
Working Fluid ◽  
Phase Flow ◽  
Two Phase ◽  
Piping Systems ◽  
Pattern Speed ◽  
Superficial Gas Velocity

Two-phase flow is a flow that is composed of two combined substances, i.e., liquid and gas. Two-phase flow phenomena can be a lot encountered in nature, for example, exhaust gas smoke, fog, rain, cloud, snow, and so forth. Moreover, in the practice of company or industry environment, the flow of the two phases can be encountered on the equipment in the form of heat exchangers, boilers, nuclear reactors, piping systems, geothermal, natural gas liquefaction, and others. Data collection in this research was carried out in 4 stages (from working fluid), namely: air-water, air-water+0% glycerin, air-water+10% glycerin, air-water+20% glycerin, and air-water+30% glycerin. The research aims to determine the void fraction by using the method of digital image processing with the software MATLAB R2014a. Based on the research results, it was obtained that when superficial gas velocity high then, the value of the void fraction obtained will increase, otherwise the higher speed of the superficial liquid then, the value of void fraction that is retrieved will decrease. The viscosity of the fluid very influenced the flow pattern bubbly and plug. It is because the higher the viscosity of fluid flow pattern speed then, the bubbly and the plug will increasingly decline, instead of getting down viscosity makes bubbly flow pattern speed, and the plug will progressively increase. The length of the bubbly and plug pattern is affected by the increasing value of homogeneous (β). As a consequence, the length of the pattern increases. In the frequency when the bubbly and plug occurred, it was obtained a high enough rate that led to the value of the void fraction generated considerable increases.Keyword: two-phase, fluid, void fraction, viscosity, flow pattern.

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