Void Fraction, Pressure Drop, and Flow Pattern Behavior for Two-Phase Non-Newtonian Slug Flow

2021 ◽  
Author(s):  
Faraj Ben Rajeb ◽  
Syed Imtiaz ◽  
Yan Zhang ◽  
Amer Aborig ◽  
Mohamed M. Awad ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Flow Pattern ◽  
Flow Regime ◽  
Void Fraction ◽  
Slug Flow ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Intermittent Flow ◽  
Phase Flow ◽  
Two Phase

Abstract Slug flow is one of the most common flow patterns in non-Newtonian two-phase flow in pipes. It is a very common occurrence in gas-liquid two-phase flow in the pipe. Usually, it is an unfavorable flow pattern due to its unsteady nature, intermittency as well as high pressure drop. The differences between slug flow and elongated bubble flow are not clear because usually these two types of flow combined under one flow category. In general, these two-phase flow regimes are commonly defined as intermittent flow. In the present study, pressure gradient, and wave behavior in slug flow have been investigated depending on experimental work. In addition, void fraction has been estimated regarding available superficial liquid and gas velocities. The experimental records of superficial velocities of gas and liquid for slug flow and other flow patterns is used to create flow regime map for the gas non-Newtonian flow system. The effect of investigated flow regime velocities for non-Newtonian/gas flow on pressure drop and void fraction is reported. Pressure drop has been discovered to be reduced in slug flow more than other flow patterns due to high shear thinning behavior.

Adiabatic Air-Water Two-Phase Flow in Circular Microchannels

2011 ◽  
Author(s):  
Aritra Sur ◽  
Dong Liu
Keyword(s):  
Pressure Drop ◽  
Flow Pattern ◽  
Slug Flow ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Water Mixture ◽  
Two Phase ◽  
Phase Pressure ◽  
Circular Microchannels

Gas-liquid two-phase flow in microchannels with hydraulic diameters of 100–500 μm exhibits drastically different flow behaviors from its counterpart in conventional macroscopic channels. Two particular issues are how to determine the two-phase flow patterns and how to predict the two-phase pressure drop at given flow conditions in these microchannels. This paper presents an experimental study of adiabatic two-phase flow of air-water mixture in circular microchannels with inner diameters of 100, 180 and 324 μm, respectively, to investigate the effects of channel size and phase velocity on the two-phase flow pattern and pressure drop. The air and water superficial velocities were in the range of 0.01–120 m/s and 0.005–5 m/s. Two-phase flow patterns were visualized using highspeed photographic technique. Four basic flow patterns, namely, bubbly flow, slug flow, ring flow and annular flow, were observed. The two-phase flow maps were then constructed and the transition boundaries between different flow regimes were identified. It was found that the slug flow is the dominant two-phase flow pattern in microchannels, and the transition boundaries generally shift to regions of higher gas superficial velocities as the channel dimension decreases. The experimental measurements of two-phase pressure drop were compared to the predictions from the available two-phase models in the literature. Results show that the flow pattern-based models provide the best prediction of two-phase pressure drop in microchannels.

Two-Phase Flow and Heat Transfer in Rectangular Micro-Channels

2003 ◽  
Author(s):  
Weilin Qu ◽  
Seok-Mann Yoon ◽  
Issam Mudawar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Heat Sinks ◽  
Phase Flow ◽  
Micro Channel ◽  
Two Phase ◽  
Micro Channels

Knowledge of flow pattern and flow pattern transitions is essential to the development of reliable predictive tools for pressure drop and heat transfer in two-phase micro-channel heat sinks. In the present study, experiments were conducted with adiabatic nitrogen-water two-phase flow in a rectangular micro-channel having a 0.406 × 2.032 mm cross-section. Superficial velocities of nitrogen and water ranged from 0.08 to 81.92 m/s and 0.04 to 10.24 m/s, respectively. Flow patterns were first identified using high-speed video imaging, and still photos were then taken for representative patterns. Results reveal that the dominant flow patterns are slug and annular, with bubbly flow occurring only occasionally; stratified and churn flow were never observed. A flow pattern map was constructed and compared with previous maps and predictions of flow pattern transition models. Annual flow is identified as the dominant flow pattern for conditions relevant to two-phase micro-channel heat sinks, and forms the basis for development of a theoretical model for both pressure drop and heat transfer in micro-channels. Features unique to two-phase micro-channel flow, such as laminar liquid and gas flows, smooth liquid-gas interface, and strong entrainment and deposition effects are incorporated into the model. The model shows good agreement with experimental data for water-cooled heat sinks.

Flow Characteristics of Adiabatic Gas-Liquid Two-Phase Flow in a Horizontal Flat Rectangular Microchannel

2011 ◽  
Author(s):  
Hideo Ide ◽  
Kentaro Satonaka ◽  
Tohru Fukano
Keyword(s):  
Void Fraction ◽  
Slug Flow ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Phase Flow ◽  
Similar Data ◽  
Two Phase ◽  
The Mean

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.

Experimental Investigation on Flow Patterns and Frictional Pressure Drop of Downward Air-Water Two-Phase Flow in Vertical Pipes

2013 ◽  
Author(s):  
Yuqing Xue ◽  
Huixiong Li ◽  
Tianyou Sheng ◽  
Changjiang Liao
Keyword(s):  
Pressure Drop ◽  
Flow Pattern ◽  
Oil Recovery ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Vertical Pipe ◽  
Two Phase Flows ◽  
Two Phase ◽  
Frictional Pressure Drop

A large amount of air need be transported into the reservoir in the deep stratum to supply oxygen to some microbes in Microbial Enhanced Oil Recovery (MEOR). Air-water two-phase flows downward along vertical pipeline during the air transportation. Base on the experiment data described in this paper, the characteristics of air-water two phase flow patterns were investigated. The flow pattern map of air-water two phase flows in the pipe with inner diameter of 65 mm was drawn, criterions of flow pattern transition were discussed, and the dynamic signals of the pressure and the differential pressure of the two phase flow were recorded to characterize the three basic flow regimes indirectly. The frictional pressure drop of downward flow in vertical pipe must not be disregarded contrast with upward two phase flow in the vertical pipe because the buoyancy must be overcame when the gas flows downward along pipe, and there would be a maximum value of frictional when the flow pattern translated from slug flow to churn flow.

Two-Phase Flow and Heat Transfer in Rectangular Micro-Channels

2004 ◽  
Vol 126 (3) ◽  
pp. 288-300 ◽  
Author(s):  
Weilin Qu ◽  
Seok-Mann Yoon ◽  
Issam Mudawar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Flow Patterns ◽  
Heat Sinks ◽  
Phase Flow ◽  
Micro Channel ◽  
Two Phase

Knowledge of flow pattern and flow pattern transitions is essential to the development of reliable predictive tools for pressure drop and heat transfer in two-phase micro-channel heat sinks. In the present study, experiments were conducted with adiabatic nitrogen-water two-phase flow in a rectangular micro-channel having a 0.406×2.032mm2 cross-section. Superficial velocities of nitrogen and water ranged from 0.08 to 81.92 m/s and 0.04 to 10.24 m/s, respectively. Flow patterns were first identified using high-speed video imaging, and still photos were then taken for representative patterns. Results reveal the dominant flow patterns are slug and annular, with bubbly flow occurring only occasionally; stratified and churn flow were never observed. A flow pattern map was constructed and compared with previous maps and predictions of flow pattern transition models. Features unique to two-phase micro-channel flow were identified and employed to validate key assumptions of an annular flow boiling model that was previously developed to predict pressure drop and heat transfer in two-phase micro-channel heat sinks. This earlier model was modified based on new findings from the adiabatic two-phase flow study. The modified model shows good agreement with experimental data for water-cooled heat sinks.

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

2010 ◽  
Vol 132 (4) ◽  
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.

Computer Programming Simulation of Two-Phase Flow Pipelines Using Mechanistic and Semi-Empirical Models

2006 ◽  
Author(s):  
Ahmad Fazeli ◽  
Ali Vatani
Keyword(s):  
Pressure Drop ◽  
Flow Regime ◽  
Two Phase Flow ◽  
Empirical Models ◽  
Intermittent Flow ◽  
Phase Flow ◽  
Liquid Holdup ◽  
Two Phase ◽  
Segregated Flow ◽  
Semi Empirical

Two-phase flow pipelines are utilized in simultaneous transferring of liquid and gas from reservoir fields to production units and refineries. In order to obtain the hydraulic design of pipelines, pressure drop and liquid holdup were calculated following pipeline flow regime determination. Two semi-empirical and mechanistical models were used. Empirical models e.g. Beggs & Brill, 1973, are only applicable in certain situations were pipeline conditions are adaptable to the model; therefore we used the Taitel & Dukler, 1976, Baker et al., 1988, Petalas & Aziz, 1998, and Gomez et al., 1999, mechanistical models which are practical in more extensive conditions. The FLOPAT code was designed and utilized which is capable of the determining the physical properties of the fluid by either compositional or non-compositional (black oil) fluid models. It was challenged in various pipeline positions e. g. horizontal, vertical and inclined. Specification of the flow regime and also pressure drop and liquid holdup could precisely be calculated by mechanistical models. The flow regimes considered in the pipeline were: stratified, wavy & annular (Segregated Flow), plug & slug (Intermittent Flow) and bubble & mist (Distributive Flow). We also compared output results against the Stanford Multiphase Flow Database which were used by Petalas & Aziz, 1998, and the effect of the flow rate, pipeline diameter, inclination, temperature and pressure on the flow regime, liquid holdup and pressure drop were studied. The outputs (flow regime, pressure drop and liquid holdup) were comparable with the existing pipeline data. Moreover, by this comparison one may possibly suggest the more suitable model for usage in a certain pipeline.

Two-Phase Flow Regime Transitions in Microchannel Tubes: The Effect of Hydraulic Diameter

2000 ◽  
Author(s):  
John W. Coleman ◽  
Srinivas Garimella
Keyword(s):  
Flow Regime ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Small Diameter ◽  
Flow Patterns ◽  
Hydraulic Diameter ◽  
Intermittent Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Mechanisms

Abstract An experimental investigation of two-phase flow mechanisms during condensation of refrigerant R134a in small diameter round and rectangular tubes was conducted. A 4.91 mm round tube, and four round tubes with hydraulic diameters ranging from 1 mm – 4 mm were studied to characterize the influence of tube miniaturization on the flow mechanisms. For each tube under consideration, flow mechanisms were recorded over the entire range of qualities 0 < x < 1, and for five different mass fluxes between 150 kg/m2-s and 750 kg/m2-s. Approximately 50 data points were recorded for each tube to obtain a comprehensive understanding of the effects of geometry, mass flux and quality on the phase-change flow mechanisms. The flow mechanisms were categorized into four different flow regimes: intermittent flow, wavy flow, annular flow, and dispersed flow. In addition, the large amount of data over a wide range of test conditions enabled the delineation of several different flow patterns within each flow regime, which provides a clearer understanding of the different modes of two-phase flow. Transition lines between the respective flow patterns and regimes on these maps were established based on the experimental data. It was found that the intermittent flow regime becomes larger as the tube hydraulic diameter is decreased. Also, the size of the wavy flow regime decreases for the small diameter tubes, and disappears completely for the 1 × 1 mm square tube. These maps and transition lines can be used to predict the flow pattern or regime that will be established for a given mass flux, quality and tube geometry.

Flow Characteristics and Frictional Pressure Drops of Gas-Liquid Two-Phase Flow in Mini-Micro Pipes and at Vena Contract and Expansion

2007 ◽  
Author(s):  
Hiroyasu Ohtake ◽  
Hideyasu Ohtaki ◽  
Yasuo Koizumi
Keyword(s):  
Pressure Drop ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Liquid Velocity ◽  
Flow Patterns ◽  
Experimental Results ◽  
Phase Flow ◽  
Two Phase ◽  
Pressure Drops ◽  
Frictional Pressure Drop

The frictional pressure drops and two-phase flow patterns of gas-liquid two-phase flow in mini-micro pipes and at vena contract and expansion were investigated experimentally. Test liquid was water; test gas was argon. The diameter of the test mini-pipe was 0.5, 0.25 and 0.12 mm, respectively. The pressure drop data and the flow pattern were collected over 2.1 < Ug < 92.5 m/s for the superficial gas velocity and 0.03 < Ul < 10 m/s for the superficial liquid velocity. The experimental results show that the flow patterns were slug, churn, ring and annular flows; pure bubbly flow pattern was not observed in a range of the present experimental conditions. The two-phase friction multiplier data for D > 0.5 mm showed to be in good agreement with the conventional correlations. On the other hand, the two-phase friction multiplier data for D < 0.25 mm differed from the calculated values by the conventional correlations. Then, thickness of liquid film around a gas plug and size of gas core were estimated and the effect of frictional pressure drop on channel size was discussed through Knudsen Number of gas and instability on liquid-gas interface. The coefficients of sudden enlargement and sudden contraction in mini-pipes for the gas-water two-phase flow were modified from the present experimental results.

Sign in / Sign up

Export Citation Format

Share Document