Gas-liquid Flow In Microchannel Research Articles

Experimental Study of Interphase Mass Transfer for Gas-Liquid Flow in Microchannel with Successive Contractions and Expansions

Experimental Study of Interphase Mass Transfer for Gas-Liquid Flow in Microchannel with Successive Contractions and Expansions

Experimental study on freezing phenomenon in gas-liquid flow in microchannels

Experimental study on freezing phenomenon in gas-liquid flow in microchannels

Experimental Study on Freezing Phenomenon in Gas-Liquid Flow in Microchannels

Experimental Study on Freezing Phenomenon in Gas-Liquid Flow in Microchannels

Gas-liquid flow characterization and mass transfer study in a microreactor for oligomerization catalyst testing

The acceleration of the development of ethylene oligomerization processes by homogeneous catalysis requires a complete characterization of the catalytic system. This work proposes to use segmented gas-liquid flow in microchannels to achieve high experimental throughput for catalyst testing.Gas-liquid flow was studied in order to validate the microreactor setup. Results showed that bubble and slug lengths vary linearly with the superficial velocities ratio following the Garstecki et al. model [21]. The impact of lateral feed in Taylor flow was explored to mimic the catalyst feed in an oligomerization test. The experiments showed that the volume of the liquid slugs increased proportionally to the additional flow rate, thereby suggesting that the majority of the liquid in the lateral feed is ultimately retained in the liquid slug.A study of mass transfer showed that the volumetric mass transfer coefficient is between 0.27 and 0.55 s−1. These values lead to a Hatta number < 0.5, thus confirming the possibility of conducting the ethylene oligomerization reaction in the chemical kinetic regime.Finally, an ethylene oligomerization test performed in the microreactor showed that the continuous microreactor system can be used for catalyst screening purpose.

Influence of Wall-Surface Wettability on Gas-Liquid Flow in Microchannel with Rectangular Cross Section

Influence of Wall-Surface Wettability on Gas-Liquid Flow in Microchannel with Rectangular Cross Section

Analysing Gas-Liquid Flow in PEM Electrolyser Micro-Channels Using a Micro-Porous Ceramic as Gas Permeable Wall

Gas-liquid flow in micro-channels of a polymer electrolyte membrane water electrolysis cell (PEMEC) is studied ex-situ experimentally. In this study, the anode transport layer and micro-channels of an interdigitated flow field are visualised. A micro-porous ceramic is used for uniformly distributing gas. Different gas-liquid flow regimes like bubbly flow, Taylor flow and annular flow are noticed. These gas-liquid flow regimes are found to be dependent on current density and water stoichiometry. Furthermore, wall dry out in Taylor and annular flow regimes is noticed. This phenomenon is due to the channel cross-section aspect ratio and gas-liquid wall contact angle. This study gives knowledge about the flow plate design for high mass transport and heat transfer rates to and from the transport layer.

Experimental investigation of two-phase gas-liquid flow in microchannel with T-junction

Using high-speed video recording and the method of dual laser scanning the gas-liquid flow was investigated in rectangular microchannels with an aspect ratio of 2.35 and 1.26. Experiments were earned out for the vertical flow of ethanol-nitrogen mixture in a microchannel with a cross section of 553×235 µm and for the horizontal flow of water-nitrogen mixture in a microchannel with a cross section of 315×250 µm. The T-mixer was used at the channel's inlet for gas-liquid flow formation. It was observed that elongated bubble, transition, and annular flows are the main regimes for a microchannel with a hydraulic diameter substantially less than the capillary constant. Using laser scanning, the maps of flow regimes for ethanol-nitrogen and water–nitrogen mixtures were obtained and discussed.

Flow regime mapping in gas-liquid flow in micro-channels

Experiments were conducted in a micro-channel with square cross-section with each side being 3 mm.nbsp Gas-liquid flow is employed for determining the flow patterns with water being liquid phase and nitrogen being gas phase.nbsp Over a wide range of gas and liquid velocities the flow patterns were studied using visual inspection technique.nbsp It is found that four types of flow regimes occurred within the range of variables considered in the present study.nbsp These are bubble flow, slug flow, channel flow and transient flow.nbsp A flow regime map is also constructed.

Film thickness measurement for elongated bubble flow in microchannel using LIF

Two-phase gas-liquid flow in microchannels occurs in a variety of modern industrial applications. Using high-speed video recording, laser scanning and method LIF the characteristics of upward gas-liquid flow in rectangular microchannels with inlet T-mixer are considered. Statistical characteristics of gas-liquid flow and distributions of the phases in cross-section of a microchannel, with hydraulic diameter less than the capillary constant, were identified in a wide range of liquid and gas flow rates. Experiments were carried out for the flow of water-nitrogen in microchannels with cross section 42×280 μm and 720×1500 μm.

Numerical modeling of gas-liquid flows in mini- and microchannels

The paper presents the results of testing a methodology for calculating two-phase flows in mini- and microchannels. The numerical methodology is based on the known fluid-in-cell method (VOF method) and the CSF procedure to account for surface tension forces. Solutions of several test problems of two-phase flow in microchannels, including the water-oil emulsion flow and gas-liquid flow in microchannels of the T-type and the stationary slug flow in a circular minichannel, were considered with the aid of this technique. Comparisons of numerical results with experimental data were carried out. A good agreement between the results was obtained.

Investigation on pressure drop characteristic and mass transfer performance of gas–liquid flow in micro-channels

Pressure drop characteristics and mass transfer performance of gas-liquid two-phase flow in micro-channels with different surface wettabilities were experimentally investigated. Side-entry T micro-channel mixers made of glass and polydimethylsiloxane were tested. Frictional pressure drop was found to decrease as the hydrophobicity of the channel surface increased. The flow patterns observed in the experiment were classified as slug flow and continuous gas phase flows. The modified Hagen-Poiseuille equation and Lockhart-Martinelli model were developed to predict the pressure drop for these two types of flow, respectively. The effect of surface wettability was heuristically incorporated in the present models which can correlate well the experimental results. Mass transfer performance was studied by the physical absorption of oxygen into de-ionized water. The results show that the volumetric mass transfer coefficients in hydrophobic micro-channels are generally higher than those in hydrophilic ones. The empirical correlations of overall volumetric mass transfer coefficients were proposed.

Hydrodynamics and mass exchange in gas-liquid slug flow in microchannels

The present state of hydrodynamics and mass transfer studies in segmented gas-liquid flow in microchannels has been analyzed. It has been shown that such parameters as gas bubble velocity, gas hold-up, relative gas bubble length, pressure drop, mass transfer coefficients from gas bubbles to liquid slugs and to liquid film, as well as mass transfer coefficient from liquid to channel wall can be satisfactorily predicted. Nevertheless, some correlations were obtained under definite conditions and should be summarized. The purpose of further research is to develop reliable methods for calculation of mass transfer coefficients as functions of channel geometry, phase properties, and phase velocities in mini- and microchannels.

Numerical Simulation and Analysis of Gas-Liquid Flow in a T-Junction Microchannel

Gas-liquid flow in microchannels is widely used in biomedicine, nanotech, sewage treatment, and so forth. Particularly, owing to the high qualities of the microbubbles and spheres produced in microchannels, it has a great potential to be used in ultrasound imaging and controlled drug release areas; therefore, gas-liquid flow in microchannels has been the focus in recent years. In this paper, numerical simulation of gas-liquid flows in a T-junction microchannel was carried out with computational fluid dynamics (CFD) software FLUENT and the Volume-of-Fluid (VOF) model. The distribution of velocity, pressure, and phase of fluid in the microchannel was obtained, the pressure distribution along the channel walls was analyzed in order to give a better understanding on the formation of microbubbles in the T-junction microchannel.

Statistical characteristics of two-phase gas-liquid flow in a vertical microchannel

This paper presents an experimental study of the structure of an upward gas-liquid flow in a vertical microchannel with a cross-sectional dimension of 0.67 × 2.00 mm and a length of 0.5 m. The tests were performed in the ranges of reduced rates of nitrogen 0.04–11.00 m/sec and water 0.07–0.41 m/sec. Using the method of two-beam laser scanning, we identified the main flow regimes (slug-bubble, slug, transient, emulsion, and annular) and determined the statistical characteristics of the two-phase flow. A map of flow regimes was constructed, the dependence of slug velocity on the reduced mixture velocity was obtained, and the friction factor for an upward gas-liquid flow in a microchannel was measured.

1012 マイクロチャンネル内気液二相流の流動特性に及ぼす気液混合法の影響の調査(G.S.流体工学(混相流),九州支部 第58期総会・講演会)

1012 マイクロチャンネル内気液二相流の流動特性に及ぼす気液混合法の影響の調査(G.S.流体工学(混相流),九州支部 第58期総会・講演会)