Gas-liquid Two-phase Flow In Microchannels Research Articles

Numerical simulation study of bubble breakup mechanism in microchannels with V-shaped obstacle

Microfluidic gas-liquid two-phase flow in microchannels plays a crucial role in diverse applications, from electronics cooling to biomedical engineering. Precisely controlling microbubble formation and breakup is essential for industrial microfluidic processes. This study investigates microbubble breakup in microchannels with V-shaped obstacles. Four breakup patterns are identified: no breakup, breakup with permanent gaps, breakup with partly obstruction, and breakup with permanent obstruction. The bubble breakup with permanent obstruction could maintain a wider flow pattern range. The bubble breakup process is categorized into three stages: squeezing, transition, and pinch-off. We observe power-law relationships between bubble characteristics and dimensionless time in each stage, and the impact of the capillary number Ca and liquid phase viscosity μL on bubble properties. This research deepens our understanding of gas-liquid two-phase flow in microchannels with obstacle structures and is relevant to analytical chemistry and fine chemical engineering applications.

The effects of channel diameter and liquid viscosity on the gas-liquid two-phase flow in microchannels

The effects of channel diameter and liquid viscosity on the gas-liquid two-phase flow in microchannels

The effects of channel diameter and of the liquid physical properties on the gas-liquid two-phase flow in microchannels

The effects of channel diameter and of the liquid physical properties on the gas-liquid two-phase flow in microchannels

The effects of channel diameter and liquid physical properties on flow patterns of the gas-liquid two-phase flow in microchannels

The effects of channel diameter and liquid physical properties on flow patterns of the gas-liquid two-phase flow in microchannels

マイクロチャンネル内気液二相流の流動現象に対する管径と液物性の影響

マイクロチャンネル内気液二相流の流動現象に対する管径と液物性の影響

マイクロチャンネル内気液二相流の流動様式と摩擦圧力損失

The studies on microfluidics have advanced with the use of microchannels in micro systems such as bioreactors, fuel cells and compact heat exchangers. It is important to elucidate gas-liquid two-phase flow phenomena in micro-channels for designing micro systems. Many analytical equations and correlations with the two-phase flow parameters such as void fraction and frictional pressure drop have been proposed in large scaled ducts. The applicability of these correlations to the microchannels must be made clear. In micro systems, various kinds of working liquids with the physical properties such as surface tension and viscosity are used in microchannels with the different sizes. Therefore, in the present paper the four kinds of microchannels with the inner 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 and liquid slug length and the two-phase frictional pressure drop were investigated. The flow characteristics of gas slugs, liquid slugs and the waves of ring film and the applicability of the correlations of the lengthes of gas slug and liquid slug, and of the two-phase frictional pressure drops which have been previously proposed to the data obtained in microchannels were also examinated.

マイクロチャンネル内気液二相流の流動様式の遷移に関する研究

マイクロチャンネル内気液二相流の流動様式の遷移に関する研究

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.

3D2 マイクロチャンネル内気液二相流の摩擦圧力損失に及ぼす壁面濡れ性の影響(<OS4・1>熱流体フロンティア(混相流))

3D2 マイクロチャンネル内気液二相流の摩擦圧力損失に及ぼす壁面濡れ性の影響(<OS4・1>熱流体フロンティア(混相流))

0203 マイクロチャンネル内気液二相流の流動様式と摩擦圧力損失に対する管内径の影響(OS2-1 混相流の多次元可視化計測,OS2 混相流の多次元可視化計測)

0203 マイクロチャンネル内気液二相流の流動様式と摩擦圧力損失に対する管内径の影響(OS2-1 混相流の多次元可視化計測,OS2 混相流の多次元可視化計測)

4D1 マイクロチャンネル内気液二相流の流動現象に及ぼす管内径の影響(<OS4・1>熱流体フロンティア(混相流)2)

4D1 マイクロチャンネル内気液二相流の流動現象に及ぼす管内径の影響(<OS4・1>熱流体フロンティア(混相流)2)

Measurement and Correlation of Pressure Drop for Gas-Liquid Two-phase Flow in Rectangular Microchannels

The pressure drop of gas-liquid two-phase flow in microchannel is of fundamental importance in heat and mass transfer processes. In this work, the pressure drop of gas-liquid two-phase flow in horizontal rectangular cross-section microchannels was measured by a pressure differential transducer system. Water, ethanol and n-propanol were used as liquid phase to study the effects of capillary number on pressure drop; air was used as the gas phase. Four microchannels with various dimensions of 100 μm × 200 μm, 100 μm × 400 μm, 100 μm × 800 μm and 100 μm × 2000 μm (depth × width) were used for determining the influence of configuration on the pressure drop. Experimental results showed that in micro-scale, the capillary number also affected the pressure drop remarkably, and in spite of only one-fold difference in aspect ratio, the variation of pressure drop reached up to near three times under the same experimental conditions. Taking the effects of aspect ratio and surface tension into account, a modified correlation for Chisholm parameter C in the Chisholm model was proposed for predicting the frictional multiplier ϕ 2 l , and the predicted values by the proposed correlation showed a satisfactory agreement with experimental data.

Void Fraction and Flow Patterns of Gas-Liquid Two-Phase Flow in a Microchannel

An optical measurement system was developed to investigate the flow phenomena of gas-liquid two-phase flow in a circular microchannel with the diameter of 100 μm. From the output wave signals which correspond to the passages of the gas and the liquid by using multiple optical fibers and photodiodes, void fraction was measured successfully. The presence of a large compressible gas volume upstream of the mixing chamber had a significant effect on the two-phase flow characteristics in the microchannel, typified by the void fraction data. The flow patterns of bubbly flow, slug flow and ring film flow were observed. The characteristics of optical signal waves corresponding to these flow patterns have been described. The time averaged value of the optical signal wave agreed well with the space averaged value of the volume fraction of the gas from video image.

1016 マイクロチャンネル内気液二相流のボイド率と圧力損失特性(GS-2,5 管内流・非定常流,研究発表講演)

Recently, gas-liquid two-phase flow in microchannels is paid increasing attention in many fields. We investigated characteristics of two-phase flow in microchannels experimentally in the slug flow region. Measured void fraction agreed with the homogenous flow model. Pressure drop cannot be described in conventional models but had an influence of surface tension. We propose a correlation of pressure drop considering the loss due to the surface tension.

906 マイクロチャンネル内気液二相流の特性を利用した液体輸送に関する研究

Gas-liquid two-phase flow in micro-channel is investigated. In the case of flow rate is relatively small, liquid and gas separate axially and liquid slugs tend to suspend in the channel due to the effect of surface tension-force. In the first step, liquid transportation system using such characteristics of liquid slug is developed and performed. Secondly, flowing slug behavior is observed by using high-speed camera in detail. Relationship between contact angle and flow velocity, pressure loss due to the surface tension is evaluated, and also shown that pressure loss per unit slug does not depend on the slug length but slug velocity.

G212 マイクロチャンネル内気液二相流の特性を利用した液体輸送に関する研究(オーガナイズドセッション11 : マイクロ熱流体システム)

Gas-liquid two-phase flow in micro-channel is investigated. In the case of flow rate is relatively small, liquid and gas separate axially and liquid slugs tend to suspend in the channel due to the effect of surface tension-force. In the first step, liquid transportation system using such characteristics of liquid slug is developed and performed. Secondly, flowing slug behavior is observed by using high-speed camera in detail. Relationship between contact angle and flow velocity, pressure loss due to the surface tension is evaluated, and also shown that pressure loss per unit slug does not depend on the slug length but slug velocity.