Micro-PIV Measurements of Flowfields Within Plugs in Two Phase Flows for µ-TAS Applications

2006 ◽  
Author(s):  
Colin King ◽  
Edmond Walsh ◽  
Ronan Grimes
Keyword(s):  
Two Phase Flow ◽  
Fluid Velocity ◽  
Internal Diameter ◽  
Immiscible Fluid ◽  
Phase Flow ◽  
Internal Circulation ◽  
Two Phase ◽  
Lab On Chip ◽  
Micro Piv ◽  
On Chip

The use of two phase flow in lab-on-chip devices, where chemical and biological reagents are enclosed within plugs separated from each other by an immiscible fluid, offers significant advantages for the development of devices with high throughput of individual heterogeneous samples. Lab-on-chip devices designed to perform the polymerase chain reaction (PCR) are a prime example of such developments. The internal circulation within the plugs used to transport the reagents affects the efficiency of the chemical reaction within the plug, due to the degree of mixing induced on the reagents by the flow regime. It has been hypothesised in the literature that all plug flows produce internal circulation. This work demonstrates experimentally that this is false, and seeks to elucidate the parameters influencing the internal circulation of plugs. The particle image velocimetry (PIV) technique offers a powerful non-intrusive tool to study such flow fields. This paper presents micro-PIV experiments carried out to study the internal circulation of aqueous plugs in two phase flow within 762μm internal diameter FEP Teflon tubing with FC-40 as the segmenting fluid. Experiments have been performed and the results are presented for plugs ranging in length from 1mm to 13mm with an average fluid velocity ranging from 0.3mm/s to 50mm/s. The results demonstrate that circulation within the plugs is not always present and requires design considerations to benefit from this phenomenon.

Identification of microfluidic two-phase flow patterns in lab-on-chip devices

2014 ◽  
Vol 24 (1) ◽  
pp. 77-83 ◽  
Author(s):  
Zhaochu Yang ◽  
Tao Dong ◽  
Einar Halvorsen
Keyword(s):  
Two Phase Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase ◽  
Lab On Chip ◽  
On Chip

On Two Phase Flow Regimes in a Microscale Direct Methanol Fuel Cell

2008 ◽  
Author(s):  
Christian Weinmu¨ller ◽  
Nicole R. Bieri ◽  
Dimos Poulikakos
Keyword(s):  
Fuel Cell ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Research Attention ◽  
Lab On Chip ◽  
Research Activities ◽  
Wide Range ◽  
Direct Methanol ◽  
On Chip

The area of microfluidics has experienced a tremendous increase in research activities in recent years with a wide range of applications, such as micro heat exchangers and energy conversion devices, microreactors, lab-on-chip devices, micro total chemical analysis systems (μTAS) etc. The occurrence of two phase flow can lead to several mechanisms enhancing or extending the performance of single phase microfluidic devices [1]. On the other hand, in a micro fuel cell the second, non-immiscible phase is considered to hamper the performance of the fuel cell [2]. Regardless of its effect, two phase flows in microfluidics deserve special research attention.

scholarly journals Studying of parameters of two-phase displacement in porous media with MRI technique

2020 ◽  
Vol 21 (5) ◽  
pp. 524
Author(s):  
Jamal Fannir ◽  
Irina Panfilova ◽  
Sébastien Leclerc ◽  
Didier Stemmelen
Keyword(s):  
Porous Medium ◽  
Magnetic Resonance ◽  
Two Phase Flow ◽  
Water Flooding ◽  
Immiscible Fluid ◽  
Phase Flow ◽  
Ambient Conditions ◽  
Two Phase ◽  
Imaging Device ◽  
Oil Saturation

This study describes experimental research on two-phase flow displacement using Magnetic Resonance Imaging (MRI) techniques. The overall purpose of this investigation is to determine kinetics process of phase trapping during (water-oil) two-phase flow, the front deformation and the phases saturation propagation along a vertical model. In these water flooding experiments, the porous medium model consists of packed beads of polystyrene (0.4 mm < dp < 0.6 mm) or sand grains (0.02 mm < dp < 0.50 mm). In order to conduct high accuracy experiments, a Nuclear Magnetic Resonance (NMR) spectrometer operating at 14 T (corresponding to a 600 MHz 1H resonance) equipped with an imaging device was used. With this equipment we can measure and visualize the two-phase flow in a vertical model of porous medium under ambient conditions. The obtained results have shown that the oil saturation profile is strongly influenced by the material properties such as the phase wetting, the sample porosity and permeability as well as the injection rate. The influence of flow velocity on the residual oil saturation was also studied. The experimental results allow an essential understanding of immiscible fluid displacement in two different types of porous medium that differ from each other mainly by the effects of wettability.

Investigation of Liquid Loading in Gas Well: Simultaneous Measurements of Drop-Size, Film Thickness and Pressure Drop

2010 ◽  
Author(s):  
Mhunir B. Alamu ◽  
Barry J. Azzopardi ◽  
Gerrit P. van der Meulen ◽  
Valente Hernandez-Perez
Keyword(s):  
Pressure Drop ◽  
Film Thickness ◽  
Drop Size ◽  
Two Phase Flow ◽  
Measurement Instrument ◽  
Dominant Frequency ◽  
Internal Diameter ◽  
Phase Flow ◽  
Two Phase ◽  
Frequency Space

The mechanism of atomization of part of the liquid film to form drops in annular two-phase flow is not entirely understood. It has been observed that drop creation only occurs when there are large disturbance waves present on the film interface. Woodmansee and Hanratty [1] observed that ripples on these waves were a precursor to drops. Though it has been reported that drops occur in bursts by Azzopardi [2], all previous drop size or concentration measurements have always been time integrated to simplify data analysis. Dynamic time averaged drop-size measurements are reported for the first time for annular two-phase flow. Experiments were carried out on a 19mm internal diameter vertical pipe with air and water as fluids. Spraytec, a laser diffraction-based, drop size measurement instrument, was used in the data acquisition. Simultaneous time-resolved measurements were made of: film thickness using conductance probes employing a pair of flush mounted rings as electrodes; and pressure gradient. The gas superficial velocity was 13–43 m/s at liquid superficial velocities of 0.05 and 0.15 m/s. Additional tests were carried out with the gas velocity at 14 m/s for liquid superficial velocities of 0.03–0.18 m/s. Though structures are not clearly visible in the signals acquired, they have been analyzed in amplitude and frequency space to yield Probability Density Function (PDF) and to identify the dominant frequency. Cross-correlation between two film thickness probes provides the wave velocities. Based on the signal analysis, links between film thickness, drop concentration and pressure drop have been identified.

scholarly journals Numerical Simulation of Evaporating Two-Phase Flow in a High-Aspect-Ratio Microchannel with Bends

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Zhenhai Pan ◽  
Justin A. Weibel ◽  
Suresh V. Garimella
Keyword(s):  
Aspect Ratio ◽  
Liquid Film ◽  
High Aspect Ratio ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Fluid Velocity ◽  
Thin Liquid Film ◽  
Heated Wall ◽  
Phase Flow ◽  
Two Phase

Despite the demand for high-performance, two-phase cooling systems, high-fidelity simulations of flow boiling in complex microchannel geometries remains a challenging numerical problem. We conduct a first-principles-based simulation of an evaporating two-phase flow in a high-aspect-ratio microchannel with bends using a volume of fluid-based numerical model. For the case shown, the lower horizontal section of the microchannel has a constant flux of 20 W/cm2 applied to the wetted wall area (heat flux at the base of 133 W/cm2); HFE-7100 vapor and liquid enter the channel at 2 m/s. The three-dimensional channel geometry requires a refined near-wall numerical mesh to resolve thin liquid film flow features. The recently developed saturated-interface-volume phase change model (Int J Heat Mass Trans 93:945-956, 2016) is implemented for prediction of mass and energy exchange across the liquid-vapor interface at a low computational cost (~80 hr; 6-core parallelization on Intel Xeon E3-1245V3). The model reveals transport details including the interface shape and fluid velocity and temperature fields. The interfacial temperature remains fixed at saturation with smooth velocity contours near the interface. The highest evaporation flux is located in the thin liquid film region near the heated wall.

Field-Scale Evaluation of Leak Detection for Gas-Liquid Two-Phase Flow in Deepwater Production Systems

2005 ◽  
Author(s):  
John M. Griffin ◽  
John Rogers Smith
Keyword(s):  
Pressure Loss ◽  
Two Phase Flow ◽  
Production Systems ◽  
Average Rate ◽  
Theoretical Method ◽  
Internal Diameter ◽  
Phase Flow ◽  
Field Scale ◽  
Flow Loop ◽  
Two Phase

This paper focuses on validating a theoretical method for the detection of leaks in deep water, multi-phase pipelines. [1] Six field-scale, two-phase flow tests were conducted to compare small leaks with a no-leak condition. These tests qualitatively demonstrate the feasibility of Scott’s concept. Knowing the characteristic pressure loss versus throughput in a line without a leak provides a basis for determining the presence of a leak by measuring pressure loss and flowrate out of the line. If the pressure loss is higher than expected for that flowrate, a leak is a likely possible cause. In these full-scale tests, a leak was readily detectable once the leak rate exceeded 16 percent for the case where the average rate exiting the line was 547 MCFPD. These tests were performed on a 3.64 inch (9.25 cm) internal diameter 9,640 foot (2,938 m) long flow loop with the leak occurring at the midpoint.

Pressure Drops and Model Modification for Two-Phase Flow in Porous Beds With Coarse Particles

2017 ◽  
Author(s):  
Xumao Zou ◽  
Liangxing Li ◽  
Liubo Kong ◽  
Huasheng Wang
Keyword(s):  
Two Phase Flow ◽  
Fluid Velocity ◽  
Experimental Studies ◽  
Test Facility ◽  
Phase Flow ◽  
Coarse Particles ◽  
Two Phase ◽  
Modified Model ◽  
Pressure Drops ◽  
Interfacial Drag

Motivated by reducing the uncertainties in coolability analysis of a debris bed, this paper proposed a modified model for the pressure drops of two phase flow through packed beds with coarse particles based on the experimental studies. The experiments are carried out on the test facility of DEBECO-LT (DEbris BEd COolability-Low Temperature), which was designed to investigate single / two-phase flow in porous beds. The coarse particles are packed in the cylindrical test section with the inner diameter of 120 mm and the height of 600 mm. Through single-phase flow tests in homogeneous beds, the reliability of the whole experimental system is ensured. Then two-phase flow tests are performed to investigate the flow characteristics, to provide basic data for verifying and modifying the existing models. The results show that, the interfacial drag in beds with coarse particles will result in a decreasing tendency in the pressure drop curves along with the fluid velocity, and the the effect of interfacial drag should be considered in the debris coolability analysis models for beds with coarse particles. Compared with the existing models, the new model shows relatively satisfactory forecasting ability, and the predictions have favorable agreement with existing experimental data under various conditions. This modified model could be applied to calculate the pressure drops of two-phase flow in coarse-particle beds.

Sign in / Sign up

Export Citation Format

Share Document