scholarly journals Non-Invasive Manipulation of Two-Phase Liquid–Liquid Slug Flow Parameters Using Magnetofluidics

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1449
Author(s):  
Anoj Winston Gladius ◽  
Simon Höving ◽  
Mehdy Mendelawi ◽  
Harikrishna Sreekumar Sheeba ◽  
David W. Agar
Keyword(s):  
Phase Separation ◽  
Slug Flow ◽  
Permanent Magnets ◽  
Process Intensification ◽  
Active Phase ◽  
Vital Role ◽  
Phase Ratio ◽  
Liquid Slug ◽  
Two Phase ◽  
Non Invasive

Liquid–liquid slug flow in a microcapillary, with its improved heat and mass transfer properties and narrow residence time, plays a vital role in process intensification. Knowledge of the flow properties in microchannels along variables’ controllability (e.g., phase ratio, slug length along with classical variables, such as pressure, temperature, and flow velocity) during operation is crucial. This work aids in this by using magnetofluidics to manipulate these parameters. A ferrofluid with reproducible properties is produced and, together with another phase, stable slug flow is generated. Micro-gear pumps and syringe pumps, with their traditional mechanical components, result in parts degrading over time due to fatigue caused by pressure differentials and corrosive chemicals. The microflow is also disturbed by the invasive nature of these pumps. A considerably energy-efficient, non-invasive alternative, with reduced mechanical interfacing is suggested in this work. It uses magnetic gradients to manipulate two-phase flow, one of which is a magnetically active phase. Conveying concepts using permanent magnets in the immediate vicinity of the flow are investigated. To operate this pump continuously and to be able to regulate the phase ratio, an electromagnetic non-invasive valve is developed. Phase separation is also carried out with an existing decanter design, modified using electromagnetism to work without a selective membrane, usually necessary for phase separation at this scale. This pump is then compared with similar pumps developed in the past.

Study of the 90° Elbows Performance as Phase Separators in an Air-Water Two-Phase Flow

2003 ◽  
Author(s):  
Valente Herna´ndez P. ◽  
Florencio Sa´nchez S. ◽  
Miguel Toledo V. ◽  
Georgiy Polupan
Keyword(s):  
Phase Separation ◽  
Slug Flow ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Pressure Gradients ◽  
Two Phase ◽  
Branch Diameter ◽  
Independent Variables ◽  
Inclination Angles ◽  
Phase Separator

In order to observe the 90° elbows performance as phase separators in an air-water two-phase flow, experimental results for the phase split which occurs at a 90° branched elbow are presented. The branched elbow geometry was varied in order to have three (branch diameter / elbow diameter) ratios and three branch inclination angles. Also the pressure was monitored at different points of the elbow with ramification in order to examine the pressure drop effect. The flow pattern upstream was mainly slug flow. First, the analysis of the main independent variables effect, (superficial velocities, branch inclination angle, ratio of diameters and pressure gradients) was carried out, then a correlation for the phase split was developed and, finally a comparison was made with data of phase separation in T junctions obtained by Azzopardi [1] and Soliman [2], as a result, a better behavior as phase separator was found for the elbow.

Capacitive determination of wall-film thickness in liquid-liquid slug flow and its application as a non-invasive microfluidic viscosity sensor

2020 ◽  
Vol 315 ◽  
pp. 112342 ◽  
Author(s):  
Linda Arsenjuk ◽  
Maximilian Wiesehahn ◽  
Elodia Morales Zimmermann ◽  
Witalij Katschan ◽  
David W. Agar
Keyword(s):  
Film Thickness ◽  
Slug Flow ◽  
Liquid Slug ◽  
Non Invasive ◽  
Wall Film ◽  
Viscosity Sensor

Numerical Simulation of Two-Phase Slug Flows in Microchannels

2009 ◽  
Author(s):  
A. Mehdizadeh ◽  
S. A. Sherif ◽  
W. E. Lear
Keyword(s):  
Surface Tension ◽  
Slug Flow ◽  
Stokes Equations ◽  
Pressure Fluctuations ◽  
Water Interface ◽  
Liquid Slug ◽  
Complex Flow ◽  
Two Phase ◽  
Air Water Interface ◽  
Slug Flows

In this paper the Navier-stokes equations for a single liquid slug have been solved in order to predict the circulation patterns within the slug. Surface tension effects on the air-water interface have been investigated by solving the Young–Laplace equation. The calculated interface shape has been utilized to define the liquid slug geometry at the front and tail interfaces of the slug. Then the effects of the surface tension on the hydrodynamics of the two-phase slug flow have been compared to those where no surface tension forces exist. The importance of the complex flow field features in the vicinity of the two interfaces has been investigated by defining a non-dimensional form of the wall shear stress. The latter quantity has been formulated based on non-dimensional parameters in order to define a general Moody friction factor for typical two-phase slug flows in microchannels. Moreover, the hydrodynamics of slug flow formation has been examined using computational fluid dynamics (CFD). The volume-of-fluid (VOF) method has been applied to monitor the growth of the instability at the air-water interface. The lengths of the slugs have been correlated to the pressure fluctuations in the mixing region of the air and water streams at an axisymmetric T-junction. The main frequencies of the pressure fluctuations have been investigated using the Fast Fourier Transform (FFT) method.

Pressure drop of two-phase liquid-liquid slug flow in square microchannels

2018 ◽  
Vol 191 ◽  
pp. 398-409 ◽  
Author(s):  
Agnieszka Ładosz ◽  
Philipp Rudolf von Rohr
Keyword(s):  
Pressure Drop ◽  
Slug Flow ◽  
Liquid Slug ◽  
Two Phase ◽  
Phase Liquid

Surface Tension Effects on Liquid Flow in Small Plastic Tubes When Gas Bubbles are Present

2005 ◽  
Vol 219 (8) ◽  
pp. 853-857 ◽  
Author(s):  
M. R. Myers ◽  
H. M. Cave ◽  
S. P. Krumdieck
Keyword(s):  
Surface Tension ◽  
High Pressure ◽  
Pressure Drop ◽  
Liquid Flow ◽  
Slug Flow ◽  
Small Diameter ◽  
Gas Bubbles ◽  
Flow Regimes ◽  
Liquid Slug ◽  
Two Phase

Two-phase intermittent gas and liquid slug flow in small diameter glass and plastic tubes was studied. Two distinct flow regimes and the transition phenomena were identified. A modified Hagen-Poiseuille relation was derived to describe the extremely high pressure drop due to the surface tension effects of pinned slug flow.

Modelling of Pressure Fluctuation With Cross Flow in a Tight-Lattice Rod Bundle

2008 ◽  
Author(s):  
Weizhong Zhang ◽  
Hiroyuki Yoshida ◽  
Kazuyuki Takase
Keyword(s):  
Numerical Simulation ◽  
Pressure Gradient ◽  
Pressure Fluctuation ◽  
Slug Flow ◽  
Reactor Core ◽  
Approximate Model ◽  
Differential Pressure ◽  
Liquid Slug ◽  
Two Phase ◽  
Simulation Code

An approximate model is presented which permits the prediction in detail of the unsteady differential pressure fluctuation behavior between subchannels in the nuclear reactor core. The instantaneous fluctuation of differential pressure between two subchannels in gas-liquid slug flow regime is deemed as a result of the intermittent nature slug flow in each subchannel. The model is based on the detailed numerical simulation result of two-phase flow that pressure drop occurs mainly in liquid slug region and in the bubble region it is negligibly small. The instantaneous fluctuation of differential pressure between the two subchannels is associated with pressure gradient in the liquid slug for each channel. In addition to a hydrostatic gradient, acceleration and frictional gradients are taken into account to predict pressure gradient in the liquid slug. This model temporarily used in conjunction with the numerical simulation code works satisfactorily to reproduce numerical simulation results for instantaneous fluctuation of differential pressure between two modeled subchannels.

Use of Two-Phase CFD Simulations to Develop a Boiling Heat Transfer Prediction Method for Slug Flow Within Microchannels

2015 ◽  
Author(s):  
Mirco Magnini ◽  
John R. Thome
Keyword(s):  
Heat Transfer ◽  
Liquid Film ◽  
Slug Flow ◽  
Boiling Heat Transfer ◽  
Prediction Method ◽  
Liquid Slug ◽  
Modeling Framework ◽  
Cfd Simulations ◽  
Two Phase ◽  
Elongated Bubble

This work presents a new boiling heat transfer prediction method for slug flow within microchannels, which is developed and benchmarked against the results of two-phase CFD simulations. The proposed method adopts a two-zone decomposition of the flow for the sequential passage of a liquid slug and an evaporating elongated bubble. The heat transfer is modeled by assuming transient heat conduction across the liquid film surrounding an elongated bubble and sequential conduction/convection within the liquid slug. Embedded submodels for estimating important flow parameters, e.g. bubble velocity and liquid film thickness, are implemented as “building blocks”, thus making the entire modeling framework totally stand-alone. The CFD simulations are performed by utilizing ANSYS Fluent v. 14.5 and the interface between the vapor and liquid phases is captured by the built-in Volume Of Fluid algorithm. Improved schemes to compute the surface tension force and the phase change due to evaporation are implemented by means of self-developed functions. The comparison with the CFD results shows that the proposed method emulates well the bubble dynamics during evaporation, and predicts accurately the time-averaged heat transfer coefficients during the initial transient regime and the terminal steady-periodic stages of the flow.

EXPERIMENTAL STUDY OF TWO-PHASE GAS-LIQUID SLUG FLOW WITH A SLIGHT DIRECTION CHANGE

2015 ◽  
Author(s):  
Rafael Fabricio Alves ◽  
Andressa Carolinne Del Monego ◽  
Cristiane Cozin ◽  
Fausto Arinos de Almeida Barbuto ◽  
Fábio Alencar Schneider ◽  
...  
Keyword(s):  
Experimental Study ◽  
Slug Flow ◽  
Liquid Slug ◽  
Two Phase ◽  
Direction Change
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