scholarly journals Precise Evaluation of Gas–Liquid Two-Phase Flow Pattern in a Narrow Rectangular Channel with Stereology Method

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3180
Author(s):  
Maciej Masiukiewicz ◽  
Stanisław Anweiler
Keyword(s):  
Flow Pattern ◽  
Transient Flow ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Rectangular Channel ◽  
Test Method ◽  
Phase Flow ◽  
Two Phase ◽  
Phase Mixture

The drive to increase the efficiency of processes based on two-phase flow demands the better precision and selection of boundary conditions in the process’ control. The two-phase flow pattern affects the phenomena of momentum, heat, and mass transfer. It becomes necessary to shift from its qualitative to quantitative evaluation. The description of the stationary structure has long been used in structural studies applied to metals and alloys. The description of a gas–liquid two-phase mixture is difficult because it changes in time and space. This paper presents a study of the precise determination of two-phase flow patterns based on stereological parameters analysis. The research area is shown against the flow map proposed by other researchers. The experiment was taken in the thin clear channel with dimensions of W = 50 × H = 1200 × T = 5 mm. The test method is based on the visualization of a two-phase air–water adiabatic flow pattern in the rectangular channel where superficial air velocities ranging from 0.006 to 0.044 m/s and the superficial water velocity ranged from 0.011 to 1.111 m/s. A high-speed camera was used for visualization. Images were analyzed with the use of stereological techniques. The study included the classification of structures according to generally accepted two-phase flow regime nomenclature for upwards co-current gas–liquid flow in a vertical rectangular channel. The result of the research was the determination of the stereological parameters’ changes with reference to the two-phase mixture flow hydrodynamics. The results were presented as waveform fluctuations in the values of stereological factors such as the volume fraction VV, interfacial surface SV, number of objects NV, mean chord l′m and the free distance λ. The description of how these parameters change with changes in phase fluxes is also presented. These waveforms help to distinguish the transient flow regimes, which allow for the automatic adjustment of the process stability. The authors found templates of the stereological parameters’ dependencies for flow pattern recognition. The research demonstrates wide possibilities of stereological methods’ application for the analysis of the two-phase gas–liquid process. The stereological model of two-phase pattern control enables the identification of process disorders.

Numerical Predication of Two-Phase Flow in Mixing Chamber of the Quick-Contact Cyclone Reactor

2012 ◽  
Vol 516-517 ◽  
pp. 945-948
Author(s):  
Yu Chun Zhang ◽  
Zhen Bo Wang ◽  
You Hai Jin
Keyword(s):  
Velocity Field ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Structure Optimization ◽  
Phase Flow ◽  
Solid Contact ◽  
Eulerian Model ◽  
Two Phase ◽  
Mixing Chamber

Gas-solid two-phase flow of the quick-contact cyclone reactor used in FCC was simulated with the multi fluid Eulerian model, especially the velocity field and volume fraction of solid in the mixing chamber was researched. The results show that flow pattern and catalyst particles concentration are non-uniform in the direction of axial, radial and tangential. The tangential gas admission increases turbulent intensity, it has a great benefit on spreading the catalyst particles uniformly, enhancing gas-solid contact effect. This work could offer a base for the structure optimization of the quick-contact reactor.

Numerical Simulation of the Interfacial Growth of the Stratified Wavy Two-Phase Flow in the Horizontal Rectangular Channel

2004 ◽  
Author(s):  
Ken-ichi Ebihara ◽  
Tadashi Watanabe
Keyword(s):  
Numerical Simulation ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Rectangular Channel ◽  
Channel Width ◽  
Phase Flow ◽  
Dimensionless Numbers ◽  
Two Phase ◽  
Flow Pattern Map ◽  
Interfacial Growth

Two-phase flow is one of the important phenomena that are found in nuclear reactors. It is required for the design and the safe operation of nuclear reactors to understand and predict the two-phase flow phenomenon by numerical analyses. This paper describes the numerical simulation of the interfacial growth of the stratified wavy two-phase flow in the horizontal rectangular channel. This flow is the cocurrent flow separated by gravity and a fundamental flow pattern of two-phase flow. The influence of the channel width upon the growth of the interfacial wave was evaluated by carrying out several simulations for the different channel width. The numerical simulation model adopted in this paper is a one-component two-phase fluid model of the lattice Boltzmann method. This model has been developed and utilized for numerical analyses of two-phase flow in recent years because it has the capability of simulating spontaneous phenomena of the interface between phases. The wave growth was observed and the dimensionless numbers that characterize the two-phase flow state were measured during the computations. The relation between the wave growth and the dimensionless numbers, which were obtained as the computational results was compared with that in the flow pattern map proposed on the basis of theoretical consideration by Taitel and Dukler. It was verified in the case of the wide channel width that the simulated relation was in agreement with that in the theoretical flow pattern map. It was shown that the narrower the channel width became, the more mass flow rate of the rare phase the interfacial growth needed and the obtained relation deviated from that in the flow pattern map.

Two-Phase Flow in a Gas Flow Channel of Polymer Electrolyte Fuel Cells

2011 ◽  
Author(s):  
Sung Chan Cho ◽  
Yun Wang
Keyword(s):  
Pressure Drop ◽  
Flow Pattern ◽  
Water Droplet ◽  
Two Phase Flow ◽  
Rectangular Channel ◽  
Aluminum Surface ◽  
Carbon Paper ◽  
Phase Flow ◽  
Two Phase ◽  
Phase Pressure

Two-phase flow behavior in a mini channel is studied by both experimental and numerical methods. Various surface conditions are considered to capture the fundamental characteristics of water droplet behavior in a PEMFC gas channel. In the considered rectangular channel with 1 mm height, critical velocity for annular flow type is measured as 1∼2 m/s of superficial air velocity. Two-phase flow pattern shows some uncertainty near transition zone with aluminum surface. With carbon paper GDL, two-phase flow pattern is stabilized. Measured two-phase pressure drop data explains the relation between two-phase flow pattern and two-phase pressure drop. Numerical simulation using VOF technique successfully mimicked the development of water droplet and corner flow as well as formation of a slug. It also explains the possibility of random slug formation with aluminum surface and stabilized two-phase flow pattern with carbon paper GDLs.

Upward Vertical Two-Phase Flow Through an Annulus—Part II: Modeling Bubble, Slug, and Annular Flow

1992 ◽  
Vol 114 (1) ◽  
pp. 14-30 ◽  
Author(s):  
E. F. Caetano ◽  
O. Shoham ◽  
J. P. Brill
Keyword(s):  
Flow Pattern ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Bubble Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Through ◽  
Physical Phenomena ◽  
Good Agreement

Mechanistic models have been developed for each of the existing two-phase flow patterns in an annulus, namely bubble flow, dispersed bubble flow, slug flow, and annular flow. These models are based on two-phase flow physical phenomena and incorporate annulus characteristics such as casing and tubing diameters and degree of eccentricity. The models also apply the new predictive means for friction factor and Taylor bubble rise velocity presented in Part I. Given a set of flow conditions, the existing flow pattern in the system can be predicted. The developed models are applied next for predicting the flow behavior, including the average volumetric liquid holdup and the average total pressure gradient for the existing flow pattern. In general, good agreement was observed between the experimental data and model predictions.

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