Bubble Behaviour in Three Phase Capillary Microreactors

2003 ◽  
Vol 1 (1) ◽  
Author(s):  
Mark J Simmons ◽  
David C Y Wong ◽  
Paul J Travers ◽  
James S Rothwell
Keyword(s):  
High Speed ◽  
Flow Characteristics ◽  
Flow Regimes ◽  
Two Phase ◽  
Microchannel Reactors ◽  
Flow Maps ◽  
Three Phase ◽  
Monolith Reactors ◽  
Produce Flow ◽  
Churn Flow

Two-phase flow characteristics in vertical capillary downflow were investigated in order to obtain understanding of the behaviour of three-phase monolith reactors. Experiments were conducted using air and dyed water in round and square capillary tubes of 2 mm and 3 mm diameter. The flow regimes and transitions observed were recorded using high speed videography and this data was used to produce flow maps for each tube. The gas and liquid superficial velocities used ranged from 0.001 to 10 m/s and 0.0001 to 1 m/s respectively. The flow regimes and their transitions were found to be a strong function of tube geometry and surface tension effects, and some differences were observed between capillaries of round and square section. This has significant implications for the design of microchannel reactors. Annular, slug-annular, slug, bubbly and churn flow regimes were observed in the round tubes; channelling/irregular flow was observed in the square tubes in place of annular and slug-annular flow.

Experimental Characterization of a Modified Airlift Pump

2014 ◽  
Author(s):  
Afshin Goharzadeh ◽  
Keegan Fernandes
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
High Speed ◽  
Water Flow Rate ◽  
High Speed Photography ◽  
Two Phase ◽  
Inner Diameter ◽  
Airlift Pump ◽  
Flow Map ◽  
Churn Flow

This paper presents an experimental investigation on a modified airlift pump. Experiments were undertaken as a function of air-water flow rate for two submergence ratios (ε=0.58 and 0.74), and two different riser geometries (i) straight pipe with a constant inner diameter of 19 mm and (ii) enlarged pipe with a sudden expanded diameter of 19 to 32 mm. These transparent vertical pipes, of 1 m length, were submerged in a transparent rectangular tank (0.45×0.45×1.1 m3). The compressed air was injected into the vertical pipe to lift the water from the reservoir. The flow map regime is established for both configurations and compared with previous studies. The two phase air-water flow structure at the expansion region is experimentally characterized. Pipeline geometry is found to have a significant influence on the output water flow rate. Using high speed photography and electrical conductivity probes, new flow regimes, such as “slug to churn” and “annular to churn” flow, are observed and their influence on the output water flow rate and efficiency are discussed. These experimental results provide fundamental insights into the physics of modified airlift pump.

Influence of Gas-Liquid Two-Phase Intermittent Flow on Hydraulic Sand Dune Migration in Horizontal Pipelines

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
Afshin Goharzadeh ◽  
Peter Rodgers ◽  
Chokri Touati
Keyword(s):  
High Speed ◽  
Sand Dune ◽  
Front Velocity ◽  
Intermittent Flow ◽  
Sand Particle ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Particle Mobility ◽  
Three Phase ◽  
Gas Ratio

This paper presents an experimental study of three-phase flows (air-water-sand) inside a horizontal pipe. The results obtained aim to enhance the fundamental understanding of sand transportation due to saltation in the presence of a gas-liquid two-phase intermittent flow. Sand dune pitch, length, height, and front velocity were measured using high-speed video photography. Four flow compositions with differing gas ratios, including hydraulic conveying, were assessed for sand transportation, having the same mixture velocity. For the test conditions under analysis, it was found that the gas ratio did not affect the average dune front velocity. However, for intermittent flows, the sand bed was transported further downstream relative to hydraulic conveying. It was also observed that the slug body significantly influences sand particle mobility. The physical mechanism of sand transportation was found to be discontinuous with intermittent flows. The sand dune local velocity (within the slug body) was measured to be three times higher than the averaged dune velocities, due to turbulent enhancement within the slug body.

Effect of Tube Diameter on Flow Phenomena of Gas-Liquid Two-Phase Flow in Microchannels

2015 ◽  
Author(s):  
Hideo Ide ◽  
Eiji Kinoshita ◽  
Ryo Kuroshima ◽  
Takeshi Ohtaka ◽  
Yuichi Shibata ◽  
...  
Keyword(s):  
Pressure Drop ◽  
High Speed ◽  
Water Solution ◽  
Flow Direction ◽  
Flow Characteristics ◽  
Tube Diameter ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Flow Phenomena ◽  
The Waves

Gas-liquid two-phase flows in minichannels and microchannels display a unique flow pattern called ring film flow, in which stable waves of relatively large amplitudes appear at seemingly regular intervals and propagate in the flow direction. In the present work, the velocity characteristics of gas slugs, ring films, and their features such as the gas slug length, flow phenomena and frictional pressure drop for nitrogen-distilled water and nitrogen-30 wt% ethanol water solution have been investigated experimentally. Four kinds of circular microchannels with diameters of 100 μm, 150 μm, 250 μm and 518 μm were used. The effects of tube diameter and physical properties, especially the surface tension and liquid viscosity, on the flow patterns, gas slug length and the two-phase frictional pressure drop have been investigated by using a high speed camera at 6,000 frames per second. The flow characteristics of gas slugs, liquid slugs and the waves of ring film are presented in this paper.

Cuttings Characteristics and Mechanics Behavior in Horizontal Wells of Liaohe Oil Field

2013 ◽  
Vol 316-317 ◽  
pp. 842-845
Author(s):  
Xian Zhong Yi ◽  
Jun Feng Zhang ◽  
Sheng Zong Jiang
Keyword(s):  
Flow Characteristics ◽  
Oil Field ◽  
Cuttings Transport ◽  
Two Phase ◽  
Fluid Medium ◽  
Washing Process ◽  
Three Phase ◽  
Flow Phenomena ◽  
Phase Liquid ◽  
Cuttings Bed

Cuttings transport of drilling and washing process in horizontal well is a typical two-phase (liquid-solid) or three-phase (gas-liquid-solid) flow phenomena. In this paper, it analyzes the flow characteristics of Huan 127-Lian H2 horizontal wellbore , then uses experimental method to study the behavior of the particle size distribution and the mechanics. This study provides an important way to master cuttings settling in fluid medium, it can explain how the cuttings bed is generated and cleared, and why the procession of cuttings of migration is stopped. In addition, measurement and analysis of drill cuttings is the basis erosion and abrasion analysis of BHA.

Effect of cavitation and free-gas entrainment on the hydraulic performance of a centrifugal pump

2020 ◽  
pp. 095765092093934
Author(s):  
Cong Wang ◽  
Yongxue Zhang ◽  
Jianjun Zhu ◽  
Zhiyi Yuan ◽  
Bohui Lu
Keyword(s):  
Centrifugal Pump ◽  
Flow Characteristics ◽  
Low Frequency ◽  
Two Phase ◽  
Free Gas ◽  
Gas Entrainment ◽  
Natural Cavitation ◽  
Low Specific Speed ◽  
Critical Cavitation ◽  
Churn Flow

An experimental study on gas–liquid two-phase flow characteristics in a low-specific-speed centrifugal pump is presented via employing multiple investigation techniques, such as visualization observation, measurements of acoustic emission and vibration, etc. Specially, three different flow conditions were inspected, namely gas locking initiation, critical cavitation with/without free-gas presence, etc. For gas locking, the drastic deterioration of the pump performance and the disrupted balance of shaft were observed. Especially, at low rotational speeds, the gas locking accompanied with intermittent or churn flow can be triggered by even lower inlet gas volumetric fractions. When it came to the cavitation flow, a small amount of gas entrainment could induce the rapid deterioration of cavitation and stimulate much higher amplitude in low-frequency band of shaft rotation. The relationship between the gas bubble trajectory and the vibration level under the backflow is discussed. The results reveal that the combined effect of the free-gas entrainment and cavitation on the pump instability is much stronger than that under natural cavitation or free-gas entrainment flow, whose fault diagnosis can be determined by the data manifested in different spectral segments.

Flow Distribution and Slug Flow Characteristics for Hydraulically Equilibrium Air-Water Two-Phase Flows in a Vertical 2×3 Rod Channel

2003 ◽  
Author(s):  
Keiko Kano ◽  
Michio Sadatomi ◽  
Akimaro Kawahara ◽  
Tsukasa Kuno
Keyword(s):  
Flow Characteristics ◽  
Prediction Method ◽  
Flow Distribution ◽  
Bubble Velocity ◽  
Accurate Estimation ◽  
Two Phase ◽  
Taylor Bubble ◽  
Rod Bundle ◽  
Superficial Gas Velocity ◽  
Churn Flow

To complete subchannel analysis for predicting thermal-hydraulic behavior of coolant in a BWR rod bundle channel, accurate estimation of fluid transfer between subchannels is necessary. In order to validate a prediction method, flow distributions data of gas and liquid phases are essential. But, such data reported so far are limited to those in a two-subchannel system alone. Then we have measured flow distributions of both phases and Taylor bubble velocity in a multi-subchannel system as called 2×3 rod bundle channel. It has been found that flow distributions of gas and liquid in bubble and annular flows under a hydraulically equilibrium flow condition are close to those of single-phase flow, but in slug-churn flow the distributions are different. In slug-churn flow, both superficial gas velocity and Taylor bubble velocity are higher in larger subchannel. These experimental data are presented and discussed in this paper.

scholarly journals Favourably regulating two-phase flow regime of flow boiling HFE-7100 in microchannels using silicon nanowires

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tamanna Alam ◽  
Wenming Li ◽  
Wei Chang ◽  
Fanghao Yang ◽  
Jamil Khan ◽  
...  
Keyword(s):  
Flow Regime ◽  
Thermal Management ◽  
Silicon Nanowires ◽  
Management System ◽  
High Speed ◽  
Flow Boiling ◽  
Flow Regimes ◽  
Phase Flow ◽  
Two Phase ◽  
Thermal Management System

AbstractHigh performance miniaturized electronic devices require enhanced, compact and reliable thermal management system. As an efficient compact space cooling technique, flow boiling in microchannels has recently gained wide acceptance. However, weak buoyancy effects and microgravity in avionics and numerous space systems operations hinder the performance of flow boiling microchannel thermal management system due to poor bubble departure capacity and unfavorable development of flow regimes. Here we report the flow boiling silicon nanowires (SiNWs) microchannels which can favorably regulate two-phase flow regimes by enhancing explosive boiling, minimizing bubble departure diameter, and smoothing flow regime transition. Extensive experimental investigations along with high speed visualizations are performed. The experiments are performed with the dielectric fluid HFE-7100 in a forced convection loop for wide range of heat and mass fluxes. High speed flow visualizations have been employed at up to 70 k frames per second (fps) to understand the boiling mechanism in terms of bubble dynamics, flow patterns, and flow regime developments for SiNWs microchannels. These studies show that SiNWs reduce intermittent flow regimes (slug/churn), improve rewetting and maintain thin liquid film at wall. Therefore, flow boiling in SiNW microchannels is promising to thermal management owing to its high heat transfer rate with low pressure drop and negligible microgravity sensitivity.

Numerical and experimental research on the erosion of solid-liquid two-phase flow in transport butterfly valve based on DEM method

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Benliang Xu ◽  
Zuchao Zhu ◽  
Zhe Lin ◽  
Dongrui Wang ◽  
Guangfei Ma
Keyword(s):  
Particle Size ◽  
Turbulence Model ◽  
High Speed ◽  
Two Phase Flow ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Butterfly Valve ◽  
Two Phase ◽  
Content Type ◽  
Solid Liquid

Purpose The purpose of this paper is to analyze the mechanism of particle erosion in butterfly valve pipelines under hydraulic transportation conditions. The results will affect the sealing and safety of butterfly valve pipelines and hopefully serve as reference for the anti-erosion design of butterfly valve pipelines. Design/methodology/approach Through the discrete element method (DEM) simulation that considers the force between particles, the detached eddy simulation (DES) turbulence model based on realizable k-epsilon is used to simulate the solid-liquid two-phase flow-induced erosion condition when the butterfly valve is fully opened. The simulation is verified by building an experimental system correctness. The solid-liquid two-phase flow characteristics, particle distribution and erosion characteristics of the butterfly valve pipeline under transportation conditions are studied. Findings The addition of particles may enhance the high-speed area behind the valve. It first increases and then decreases with increasing particle size. With increasing particle size, the low-velocity particles change from being uniformly distributed in flow channel to first gathering in the front of the valve and, then, to gathering in lower part of it. Fluid stagnation at the left arc-shaped flange leads to the appearance of two high-speed belts in the channel. With increasing fluid velocity, high-speed belts gradually cover the entire valve surface by focusing on the upper and lower ends, resulting in the overall aggravation of erosion. Originality/value Considering the complexity of solid-liquid two-phase flow, this is the first time that the DEM method with added inter-particle forces and the DES turbulence model based on realizable k-epsilon has been used to study the flow characteristics and erosion mechanism of butterfly valves under fully open transportation conditions.

scholarly journals Efficient Preparation of Bafilomycin A1 from Marine Streptomyces lohii Fermentation Using Three-Phase Extraction and High-Speed Counter-Current Chromatography

Marine Drugs ◽  
2020 ◽  
Vol 18 (6) ◽  
pp. 332
Author(s):  
Ye Yuan ◽  
Xiaoping He ◽  
Tingting Wang ◽  
Xingwang Zhang ◽  
Zhong Li ◽  
...  
Keyword(s):  
Crude Extract ◽  
High Speed ◽  
Solvent System ◽  
Bafilomycin A1 ◽  
Middle Phase ◽  
Two Phase ◽  
Rapid Separation ◽  
Lower Phase ◽  
Three Phase ◽  
Counter Current

An efficient strategy was developed for the rapid separation and enrichment of bafilomycin A1 (baf A1) from a crude extract of the marine microorganism Streptomyces lohii fermentation. This strategy comprises liquid−liquid extraction (LLE) with a three-phase solvent system (n-hexane–ethyl acetate–acetonitrile–water = 7:3:5:5, v/v/v/v) followed by separation using high-speed counter-current chromatography (HSCCC). The results showed that a 480.2-mg fraction of baf A1-enriched extract in the middle phase of the three-phase solvent system was prepared from 4.9 g of crude extract after two consecutive one-step operations. Over 99% of soybean oil, the main hydrophobic waste in the crude extract, and the majority of hydrophilic impurities were distributed in the upper and lower phase, respectively. HSCCC was used with a two-phase solvent system composed of n-hexane–acetonitrile–water (15:8:12, v/v/v) to isolate and purify baf A1 from the middle phase fraction, which yielded 77.4 mg of baf A1 with > 95% purity within 90 min. The overall recovery of baf A1 in the process was determined to be 95.7%. The use of a three-phase solvent system represents a novel strategy for the simultaneous removal of hydrophobic oil and hydrophilic impurities from a microbial fermentation extract.

Characterization of Two-Phase Flow Patterns in Small Round Tubes

2014 ◽  
Vol 525 ◽  
pp. 256-259
Author(s):  
Wen Peng Hong ◽  
Guo Qing Niu ◽  
Ming Liang Jin
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase ◽  
High Speed Video ◽  
Video Systems ◽  
Small Tube

To investigate flow characteristics by high speed video systems, experimental study was conducted to gas-liquid two-phase flow in horizontal round small tube with diameter of 5.5 and 2.6 mm, the typical flow pattern images were obtained, but stratified flow of the conventional size horizontal channel had not been discovered. Gas and liquid superficial velocities range from 0.1 to 100 ms-1, and 0.01to 10.0 ms-1 respectively. Flow patterns for co-current flow of air-water mixtures in horizontal round tubes are determined by high-speed video analysis to develop flow regime maps and the transitions between these flow regimes. Comparisons with the relevant literatures show that diameter and surface tension effects play an important role in determining the flow patterns and transitions between them.

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