The wall wettability of microchannels plays an important role in the gas-liquid mass transfer dynamics under Taylor flow.In this study,we regulated the contact angle of the wall surface through surface chemical grafti...The wall wettability of microchannels plays an important role in the gas-liquid mass transfer dynamics under Taylor flow.In this study,we regulated the contact angle of the wall surface through surface chemical grafting polymerization under controlled experimental conditions.The dynamic changes of CO_(2)bubbles flowing along the microchannel were captured by a high-speed video camera mounted on a stereo microscope,whilst a unit cell model was employed to theoretically investigate the gas-liquid mass transfer dynamics.We quantitatively characterized the effects of wall wettability,specifically the contact angle,on the formation mechanism of gas bubbles and mass transfer process experimentally.The results revealed that the gas bubble velocity,the overall volumetric liquid phase mass transfer coefficients(kLa),and the specific interfacial area(a)all increased with the increase of the contact angle.Conversely,gas bubble length and leakage flow decreased.Furthermore,we proposed a new modified model to predict the gas-liquid two-phase mass transfer performance,based on van Baten’s and Yao’s models.Our proposed model was observed to agree reasonably well with experimental observations.展开更多
The lifting efficiency and stability of gas lift well are affected by the socalled slippage-loss effect in gas-liquid two-phase flow.The existing studies on this subject have generally been based on vertical and horiz...The lifting efficiency and stability of gas lift well are affected by the socalled slippage-loss effect in gas-liquid two-phase flow.The existing studies on this subject have generally been based on vertical and horizontal wells.Only a few of them have considered inclined pipes.In the present work a new focused study is presented along these lines.More specifically,we use the non-slip pressure drop model with Flanigan’s fluctuation correction coefficient formula(together with the parameters of slippage density,slippage pressure drop and slippage ratio)to analyze the influence of the inclination angle on slippage loss for different conditions(different gas-liquid superficial velocity and pipe diameters).Moreover,the“standard regression coefficient method”is used for multi-factor sensitivity analysis.The experimental results indicate that slippage loss is affected by multiple factors,and the influence of the inclination angle on slippage loss is less significant than other factors.The change of the slippage pressure drop with the superficial velocity of gas-liquid is similar to that of the total pressure drop.The inclination angles of 45°and 60°have the greatest influence on slippage loss.The correlation between slippage density and slippage ratio is not obvious.Using the so-called slippage ratio seems to be a more accurate option to evaluate the degree of slippage loss.展开更多
The vibration response of a free-hanging flexible riser induced by internal gas-liquid slug flow was studied experimentally in a small-diameter tube model based on Froude number criterion. The flow regime in a curved ...The vibration response of a free-hanging flexible riser induced by internal gas-liquid slug flow was studied experimentally in a small-diameter tube model based on Froude number criterion. The flow regime in a curved riser model and the response displacements of the riser were simultaneously recorded by high speed cameras. The gas superficial velocity ranges from 0.1 m/s to 0.6 m/s while the liquid superficial velocity from 0.06 m/s to 0.3 m/s.Severe slugging type 3, unstable oscillation flow and relatively stable slug flow were observed in the considered flow rates. Severe slugging type 3 characterized by premature gas penetration occurs at relatively low flow rates. Both the cycle time and slug length become shorter as the gas flow rate increases. The pressure at the riser base undergoes a longer period and larger amplitude of fluctuation as compared with the other two flow regimes. Additionally, severe slugging leads to the most vigorous in-plane vibration. However, the responses in the vertical and horizontal directions are not synchronized. The vertical vibration is dominated by the second mode while the horizontal vibration is dominated by the first mode. Similar to the vortex-induced vibration, three branches are identified as initial branch, build-up branch and descending branch for the response versus the mixture velocity of gas-liquid flow.展开更多
Fibrous filters are often used to remove contaminants including both dusts and liquid droplets from natural gas.This paper aims to evaluate the gas-liquid separation performance of three types of cartridge filters use...Fibrous filters are often used to remove contaminants including both dusts and liquid droplets from natural gas.This paper aims to evaluate the gas-liquid separation performance of three types of cartridge filters used in the West-East natural gas transmission project.The comparison of the original pressure drop of clean filters and the evolution of pressure drop as liquid droplets deposited in the filter media are described.The original pressure drops of these filters were similar but the pressure drops at a steady state were different.Fractional efficiency was used to study the separation performance of cartridge filters.Droplets at the outlet of the filters had small diameters,no more than 3 μm,but were very numerous.The effect of filtration velocity on gas-liquid separation performance was analyzed.Higher filtration velocity indicated better gas-liquid separation performance.Finally the quality factor related to pressure drop and filtration efficiency was applied to evaluate the gas-liquid separation performance.展开更多
Gas-liquid two-phase flow widely exits in production and transportation of petroleum industry.Characterizing gas-liquid flow and measuring flow parameters represent challenges of great importance,which contribute to t...Gas-liquid two-phase flow widely exits in production and transportation of petroleum industry.Characterizing gas-liquid flow and measuring flow parameters represent challenges of great importance,which contribute to the recognition of flow regime and the optimal design of industrial equipment.In this paper,we propose a novel complex network-based deep learning method for characterizing gas-liquid flow.Firstly,we map the multichannel measurements to multiple limited penetrable visibility graphs(LPVGs)and obtain their degree sequences as the graph representation.Based on the degree distribution,we analyze the complicated flow behavior under different flow structures.Then,we design a dual-input convolutional neural network to fuse the raw signals and the graph representation of LPVGs for the classification of flow structures and measurement of gas void fraction.We implement the model with two parallel branches with the same structure,each corresponding to one input.Each branch consists of a channel-projection convolutional part,a spatial-temporal convolutional part,a dense block and an attention module.The outputs of the two branches are concatenated and fed into several full connected layers for the classification and measurement.At last,our method achieves an accuracy of 95.3%for the classification of flow structures,and a mean squared error of 0.0038 and a mean absolute percent error of 6.3%for the measurement of gas void fraction.Our method provides a promising solution for characterizing gas-liquid flow and measuring flow parameters.展开更多
The flow ideality of bubbly microflow remains unclear even though it is vital for the design of microreactors,especially the ideality of bubble swarm microflow for large-scale gas-liquid microreaction processes.This w...The flow ideality of bubbly microflow remains unclear even though it is vital for the design of microreactors,especially the ideality of bubble swarm microflow for large-scale gas-liquid microreaction processes.This work is the first time to report the ideality analysis of the microbubble swarm in a relatively large microchannel.The bubble swarm microflow has undergone two conditions:quasihomogeneous plug flow and liquid phase/gas-liquid qua si-homogeneous phase two-phase laminar flow.Both the deviations of void fraction and bubble velocity from the ideal plug flow can divide into two parts,and the two transition points simultaneously happen at the velocity ratio of 1.25.There exists a critical capillary number to maintain the quasi-homogeneous plug flow,which could be regarded as the general laws for the design of gas-liquid microreactors.Finally,a novel model is developed to predict the bubble velocity.This work could be very helpful for the large-scale gas-liquid microreactors design.展开更多
Tetracycline(TC)is an antibiotic mainly used in livestock production and respiratory infection.Traditional methods are not effective in removing TC from solution.In this study,TC was degraded by gas–liquid plasma in ...Tetracycline(TC)is an antibiotic mainly used in livestock production and respiratory infection.Traditional methods are not effective in removing TC from solution.In this study,TC was degraded by gas–liquid plasma in the presence of rGO-TiO_(2)in solution.The rGO-TiO_(2)was prepared by modified hummers and hydrothermal method.The electrical and optical properties of the gas–liquid discharge plasma were studied and the produced long-lived reactive species were analyzed by spectrophotometer.The degradation efficiency of TC was improved by 41.4%after plasma treatment for 12 min in presence of 30 mg l-1 r GO-TiO_(2)compared to that with plasma alone.The degradation efficiency increased with increasing discharge power,but as the initial concentration was increased from 20 to 80 mg l-1,the degradation efficiency of TC decreased.The initial p H had no significant effect on the degradation of TC.The intermediate products were determined by UV–vis spectrophotometry and ESI(+)–MS,and the degradation mechanism was analyzed.The reactive species,including O_(3),·OH,and H_(2)O_(2),etc.,produced in the plasma/catalyst system attracted electron-rich functional groups(amino group,aromatic ring,and double bond).Therefore,the gas–liquid plasma/catalyst system could be an effective and promising method for pharmaceutical wastewater treatment in future.展开更多
Dedicated experiments and numerical simulations have been conducted to investigate the splitting characteristics of a gas-liquid two phase flow at a T junction.The experiments were carried out for different gas-liquid...Dedicated experiments and numerical simulations have been conducted to investigate the splitting characteristics of a gas-liquid two phase flow at a T junction.The experiments were carried out for different gas-liquid velocities.The flow rates in the two branches were measured accurately to determine how the two considered phases distribute in the two outlets.The experimental results have shown that when the two outlet pressures are asymmetric,the two-phase flow always tends to flow into the outlet which has a lower pressure.As the inlet liquid velocity increases,however,the two-phase flow gradually tends to split evenly.Compared with the experiment results,the pressure difference between the two outlets can be determined more accurately by means of numerical simulation.The trends of experimental results and simulations are in very good agreement.展开更多
The hysteresis of gas-liquid mass transfer rate and the corresponding radial liquiddistribution in a trickle bed reactor are measured to provide evidence for the correlation between thesetwo behaviors.Experimental res...The hysteresis of gas-liquid mass transfer rate and the corresponding radial liquiddistribution in a trickle bed reactor are measured to provide evidence for the correlation between thesetwo behaviors.Experimental results indicate that the hysteresis of gas-liquid mass transfer originatesfrom the nonuniformity of the hydrodynamic state of gas-liquid flow and the radial maldistributionof local k<sub>gia</sub> corresponds very well to the radial maldistribution of liquid flow in the bed.The localliquid flow rate is also found to be nonuniform in the azimuthal direction.In view of maldistributedliquid flow even in the pulsing flow regime,the conventional plug flow model seems oversimplifiedfor describing the behavior of a trickle bed.展开更多
Real-time laser holographic interferometry was applied to measure liquid concentrations of CO2 in the vicinity of gas-liquid free interface under the conditions of cocurrent gas-liquid flow for absorption of CO2 by et...Real-time laser holographic interferometry was applied to measure liquid concentrations of CO2 in the vicinity of gas-liquid free interface under the conditions of cocurrent gas-liquid flow for absorption of CO2 by ethanol. The influences of the Reynolds number on the measurable interface concentration and on the film thickness were discussed. The results show that CO2 concentration decreases exponentially along the mass transfer direction, and the concentration gradient increases as Reynolds number of either liquid or gas increases. CO2 concentrations fluctuate slightly along the direction of flow; on the whole, there is an increase in CO2 concentration. The investiga- tion also demonstrated that film thickness decreases with the increase of Reynolds number of either of the two phases. Sherwood number representing the mass transfer coefficient was finally correlated as a function of the hy- drodynamic parameters and the physical properties.展开更多
1 INTRODUCTIONTrickle bed reactors are widely used in the process industry,particularly in petroleumhydroprocessing operations,and have been extensively studied by chemical engineers.In atrickle bed reactor,the gas an...1 INTRODUCTIONTrickle bed reactors are widely used in the process industry,particularly in petroleumhydroprocessing operations,and have been extensively studied by chemical engineers.In atrickle bed reactor,the gas and liquid flow cocurrently down through the packed bedand undergo chemical reactions.However,there exist multiple hydrodynamic stateswhich correspond to either uniform or,in most cases,nonuniform radial distributionof the gas and liquid flows in the packed section.Moreover,the hydrodynamic state展开更多
A double-chamber gas-liquid phase DBD reactor(GLDR), consisting of a gas-phase discharge chamber and a gas-liquid discharge chamber in series, was designed to enhance the degradation of benzene and the emission of NOx...A double-chamber gas-liquid phase DBD reactor(GLDR), consisting of a gas-phase discharge chamber and a gas-liquid discharge chamber in series, was designed to enhance the degradation of benzene and the emission of NOx. The performance of the GLDR on discharge characteristics,reactive species production and benzene degradation was compared to that of the single-chamber gas phase DBD reactor(GPDR). The effects of discharge gap, applied voltage, initial benzene concentration, gas flow rate and solution conductivity on the degradation and energy yield of benzene in the GLDR were investigated. The GLDR presents a higher discharge power, higher benzene degradation and higher energy yield than that of the GPDR. NO2 emission was remarkably inhibited in the GLDR, possibly due to the dissolution of NO2 in water. The benzene degradation efficiency increased with the applied voltage, but decreased with the initial concentration, gas flow rate, and gas discharge gap, while the solution conductivity presented less influence on benzene degradation. The benzene degradation efficiency and the energy yield reached 61.11% and 1.45 g k Wh-1 at 4 mm total gas discharge gap, 15 k V applied voltage, 200 ppm benzene concentration,0.2 L min-1 gas flow rate and 721 μS cm-1 water conductivity. The intermediates and byproducts during benzene degradation were detected by FT-IR, GC-MS and LC-MS primarily, and phenols,COx, and other aromatic substitutes, O3, NOx, etc, were determined as the main intermediates.According to these detected byproducts, a possible benzene degradation mechanism was proposed.展开更多
To investigate the morphological evolution of the whole growth and aggregation processes of hydrate crystals near the gas–liquid interface,we used a high-pressure visual reactor with high-speed camera to capture the ...To investigate the morphological evolution of the whole growth and aggregation processes of hydrate crystals near the gas–liquid interface,we used a high-pressure visual reactor with high-speed camera to capture the micromorphology of hydrate particles in a natural gas+pure water system with pressure from 2.6 to 3.6 MPa and sub-cooling from 4.7 to 6.23C.The results showed that under low sub-cooling conditions,the amount and size of particles increased first and then decreased in the range of 0–330 lm,and the small particles always dominated.These particles can be roughly classified into two categories:planar flake particles and polyhedral solid particles.Then,the concept of maximum growth dominant particle size was proposed to distinguish the morphological boundary of growth and aggregation.In addition,the micro model was established to better reflect the effects of particle formation process and evolution mechanism near the gas–liquid interface under stirring condition.The results of this study can provide a guidance for flow assurance in multiphase pipeline.展开更多
Atmospheric pressure plasma technology is gaining increasing importance because it is a simple and tunable synthesis process for the production of metallic nanoparticles.In addition to the development of the power sup...Atmospheric pressure plasma technology is gaining increasing importance because it is a simple and tunable synthesis process for the production of metallic nanoparticles.In addition to the development of the power supply,improving the reactor is also one of the main strategies to enhanee the utility.In this study,a simple reactor for the gas-liquid discharge plasma induced by argon gas was applied to synthesize silver nanopailicles from silver nitrate(AgNO3)in solution.An AC power supply with a peak voltage of 3.5 kV was used.The frequency and on-time were set to 50 kHz and 2.5“s,respectively.The oscilloscope showed that the rising time was approximately 2“s.The ethanol was used as the source for the reactive reducing agent.No more additional comp on ents existed in the solution during the discharge and neither of the electrodes was in contact with the treated solution.The temperature in creased by 10°C within 1 min without a cooling system.Carbon was the main impurity and was expected to be produced from the decomposition of the organics under the plasma.The elevated temperature decreased the organic by-products by evaporation and could also decrease the production of carbon.Transmission electron microscopy showed that the spherical silver nanoparticles with a size of approximately 10 nm were synthesized with a crystal structure and that a low concentration of ethanol prefers the production of the mono-dispersed colloid.展开更多
In order to eliminate mal-distribution and ensure the side arm to produce desirable gas quality a special distributor is proposed. The experimental distributor mainly consists of a straight through section,a gas extra...In order to eliminate mal-distribution and ensure the side arm to produce desirable gas quality a special distributor is proposed. The experimental distributor mainly consists of a straight through section,a gas extraction line,a liquid extraction line and a side arm branch. A gas orifice and a liquid orifice are mounted at the gas and liquid extraction line respectively to control the outlet gas quality. The diameter of the liquid orifice was set to 2. 50 mm and three gas orifices with different size( dG= 2. 65,5. 00,10. 00 mm) were tested. The experiments were carried out at an air-water two-phase flow loop. The gas superficial velocity ranged from 6. 0 to 20. 0 m /s and the liquid superficial velocity was in the range of 0. 02- 0. 18 m /s. Flow patterns such as wave flow,slug flow and annular flow were observed. The gas quality of the side arm branch was found mainly determined by the flow area ratio of the gas orifice to the liquid orifice and independent of gas and liquid superficial velocity,flow patterns and extraction flux.展开更多
The flow patterns and the void fraction related to a gas-liquid two-phase flow in a small channel are experimentally studied.The test channel is a transparent quartz glass circular channel with an inner diameter of 6....The flow patterns and the void fraction related to a gas-liquid two-phase flow in a small channel are experimentally studied.The test channel is a transparent quartz glass circular channel with an inner diameter of 6.68 mm.The working fluids are air and water and their superficial velocities range from 0.014 to 8.127 m/s and from 0.0238 to 0.556 m/s,respectively.The void fraction is determined using the flow pattern images captured by a high-speed camera,while quick closing valves are used for verification.Four flow patterns are analyzed in experiments:slug flow,bubbly flow,annular flow and stratified flow.For intermittent flows(bubbly flow and slug flow),the cross-sectional void fraction is in a borderline condition while its probability distribution function(PDF)image displays a bimodal structure.For continuous flows(annular flow and stratified flow)the cross-sectional void fraction behaves as a fluctuating continuous curve while the(PDF)image displays a single peak structure.The volumetric void fraction data are also compared with available predictive formulas,and the results show that the agreement is very good.An effort is also provided to improve the so-called Gregory and Scott model using the available data.展开更多
In the paper, a dynamical model of gas-liquid mixture motion through a pipeline with regard to change of rheological properties that occur as a result of heat-exchange process, is constructed, and the solutions of the...In the paper, a dynamical model of gas-liquid mixture motion through a pipeline with regard to change of rheological properties that occur as a result of heat-exchange process, is constructed, and the solutions of the obtained connected differential equations are given. Analytic expression allowing to determine pressure change along the length of a pipeline, is obtained.展开更多
Liquid film cooling as an advanced cooling technology is widely used in space vehicles.Stable operation of liquid film along the rocket combustion inner wall is crucial for thermal protection of rocket engines.The sta...Liquid film cooling as an advanced cooling technology is widely used in space vehicles.Stable operation of liquid film along the rocket combustion inner wall is crucial for thermal protection of rocket engines.The stability of liquid film is mainly determined by the characteristics of interfacial wave,which is rarely investigated right now.How to improve the stability of thin film has become a hot spot.In view of this,an advanced model based on the conventional Volume of Fluid(VOF)model is adopted to investigate the characteristics of interfacial wave in gas-liquid flow by using OpenFOAM,and the mechanism of formation and development of wave is revealed intuitively through numerical study.The effects from gas velocity,surface tension and dynamic viscosity of liquid(three factors)on the wave are studied respectively.It can be found that the gas velocity is critical to the formation and development of wave,and four modes of droplets generation are illustrated in this paper.Besides,a gas vortex near the gas-liquid interface can induce formation of wave easily,so changing the gas vortex state can regulate formation and development of wave.What’s more,the change rules of three factors influencing on the interfacial wave are obtained,and the surface tension has a negative effect on the formation and development of wave only when the surface tension coefficient is above the critical value,whereas the dynamic viscosity has a positive effect in this process.Lastly,the maximum height and maximum slope angle of wave will level off as the gas velocity increases.Meanwhile,the maximum slope angle of wave is usually no more than 38°,no matter what happens to the three factors.展开更多
基金the financial supports from National Natural Science Foundation of China(21978250,22208278)Natural Science Foundation of Shandong Province(ZR2020KB013,ZR2020QE211,2019KJC012).
文摘The wall wettability of microchannels plays an important role in the gas-liquid mass transfer dynamics under Taylor flow.In this study,we regulated the contact angle of the wall surface through surface chemical grafting polymerization under controlled experimental conditions.The dynamic changes of CO_(2)bubbles flowing along the microchannel were captured by a high-speed video camera mounted on a stereo microscope,whilst a unit cell model was employed to theoretically investigate the gas-liquid mass transfer dynamics.We quantitatively characterized the effects of wall wettability,specifically the contact angle,on the formation mechanism of gas bubbles and mass transfer process experimentally.The results revealed that the gas bubble velocity,the overall volumetric liquid phase mass transfer coefficients(kLa),and the specific interfacial area(a)all increased with the increase of the contact angle.Conversely,gas bubble length and leakage flow decreased.Furthermore,we proposed a new modified model to predict the gas-liquid two-phase mass transfer performance,based on van Baten’s and Yao’s models.Our proposed model was observed to agree reasonably well with experimental observations.
基金supported by National Natural Science Foundation of China(No.61572084)the National Key Research and Development Program of China(2017ZX05030-005,2019D-4413).
文摘The lifting efficiency and stability of gas lift well are affected by the socalled slippage-loss effect in gas-liquid two-phase flow.The existing studies on this subject have generally been based on vertical and horizontal wells.Only a few of them have considered inclined pipes.In the present work a new focused study is presented along these lines.More specifically,we use the non-slip pressure drop model with Flanigan’s fluctuation correction coefficient formula(together with the parameters of slippage density,slippage pressure drop and slippage ratio)to analyze the influence of the inclination angle on slippage loss for different conditions(different gas-liquid superficial velocity and pipe diameters).Moreover,the“standard regression coefficient method”is used for multi-factor sensitivity analysis.The experimental results indicate that slippage loss is affected by multiple factors,and the influence of the inclination angle on slippage loss is less significant than other factors.The change of the slippage pressure drop with the superficial velocity of gas-liquid is similar to that of the total pressure drop.The inclination angles of 45°and 60°have the greatest influence on slippage loss.The correlation between slippage density and slippage ratio is not obvious.Using the so-called slippage ratio seems to be a more accurate option to evaluate the degree of slippage loss.
基金financially supported by the National Natural Science Foundation of China(Grant No.11502220)the Youth Science&Technology Foundation of Sichuan Province(Grant No.2017JQ0055)the Youth Scientific and Technological Innovation Team of the Safety of Deep-Water Pipe Strings of Southwest Petroleum University(Grant No.2017CXTD06)
文摘The vibration response of a free-hanging flexible riser induced by internal gas-liquid slug flow was studied experimentally in a small-diameter tube model based on Froude number criterion. The flow regime in a curved riser model and the response displacements of the riser were simultaneously recorded by high speed cameras. The gas superficial velocity ranges from 0.1 m/s to 0.6 m/s while the liquid superficial velocity from 0.06 m/s to 0.3 m/s.Severe slugging type 3, unstable oscillation flow and relatively stable slug flow were observed in the considered flow rates. Severe slugging type 3 characterized by premature gas penetration occurs at relatively low flow rates. Both the cycle time and slug length become shorter as the gas flow rate increases. The pressure at the riser base undergoes a longer period and larger amplitude of fluctuation as compared with the other two flow regimes. Additionally, severe slugging leads to the most vigorous in-plane vibration. However, the responses in the vertical and horizontal directions are not synchronized. The vertical vibration is dominated by the second mode while the horizontal vibration is dominated by the first mode. Similar to the vortex-induced vibration, three branches are identified as initial branch, build-up branch and descending branch for the response versus the mixture velocity of gas-liquid flow.
文摘Fibrous filters are often used to remove contaminants including both dusts and liquid droplets from natural gas.This paper aims to evaluate the gas-liquid separation performance of three types of cartridge filters used in the West-East natural gas transmission project.The comparison of the original pressure drop of clean filters and the evolution of pressure drop as liquid droplets deposited in the filter media are described.The original pressure drops of these filters were similar but the pressure drops at a steady state were different.Fractional efficiency was used to study the separation performance of cartridge filters.Droplets at the outlet of the filters had small diameters,no more than 3 μm,but were very numerous.The effect of filtration velocity on gas-liquid separation performance was analyzed.Higher filtration velocity indicated better gas-liquid separation performance.Finally the quality factor related to pressure drop and filtration efficiency was applied to evaluate the gas-liquid separation performance.
基金supported by the National Natural Science Foundation of China under Grants 61922062 and 61873181。
文摘Gas-liquid two-phase flow widely exits in production and transportation of petroleum industry.Characterizing gas-liquid flow and measuring flow parameters represent challenges of great importance,which contribute to the recognition of flow regime and the optimal design of industrial equipment.In this paper,we propose a novel complex network-based deep learning method for characterizing gas-liquid flow.Firstly,we map the multichannel measurements to multiple limited penetrable visibility graphs(LPVGs)and obtain their degree sequences as the graph representation.Based on the degree distribution,we analyze the complicated flow behavior under different flow structures.Then,we design a dual-input convolutional neural network to fuse the raw signals and the graph representation of LPVGs for the classification of flow structures and measurement of gas void fraction.We implement the model with two parallel branches with the same structure,each corresponding to one input.Each branch consists of a channel-projection convolutional part,a spatial-temporal convolutional part,a dense block and an attention module.The outputs of the two branches are concatenated and fed into several full connected layers for the classification and measurement.At last,our method achieves an accuracy of 95.3%for the classification of flow structures,and a mean squared error of 0.0038 and a mean absolute percent error of 6.3%for the measurement of gas void fraction.Our method provides a promising solution for characterizing gas-liquid flow and measuring flow parameters.
基金financial support from National Natural Science Foundation of China(21991104)。
文摘The flow ideality of bubbly microflow remains unclear even though it is vital for the design of microreactors,especially the ideality of bubble swarm microflow for large-scale gas-liquid microreaction processes.This work is the first time to report the ideality analysis of the microbubble swarm in a relatively large microchannel.The bubble swarm microflow has undergone two conditions:quasihomogeneous plug flow and liquid phase/gas-liquid qua si-homogeneous phase two-phase laminar flow.Both the deviations of void fraction and bubble velocity from the ideal plug flow can divide into two parts,and the two transition points simultaneously happen at the velocity ratio of 1.25.There exists a critical capillary number to maintain the quasi-homogeneous plug flow,which could be regarded as the general laws for the design of gas-liquid microreactors.Finally,a novel model is developed to predict the bubble velocity.This work could be very helpful for the large-scale gas-liquid microreactors design.
基金financially supported by National Natural Science Foundation of China(Nos.51777206 and 51541807)Natural Science Foundation of Anhui Province(Nos.1908085MA29,1708085MB47 and 1708085MA13)+4 种基金Doctoral Fund of Ministry of Education of China(No.2017M612058)Specialized Research Fund for the Doctoral Program of Hefei University of Technology(No.JZ2016HGBZ0769)Chinese Academy of Sciences under Grant No.DSJJ-14-YY02Science and Technology Cooperation Program between China and Finland(No.2017YFE0115200)Hong Kong Research Grants Council(RGC)General Research Funds(GRF)(No.City U 11205617)。
文摘Tetracycline(TC)is an antibiotic mainly used in livestock production and respiratory infection.Traditional methods are not effective in removing TC from solution.In this study,TC was degraded by gas–liquid plasma in the presence of rGO-TiO_(2)in solution.The rGO-TiO_(2)was prepared by modified hummers and hydrothermal method.The electrical and optical properties of the gas–liquid discharge plasma were studied and the produced long-lived reactive species were analyzed by spectrophotometer.The degradation efficiency of TC was improved by 41.4%after plasma treatment for 12 min in presence of 30 mg l-1 r GO-TiO_(2)compared to that with plasma alone.The degradation efficiency increased with increasing discharge power,but as the initial concentration was increased from 20 to 80 mg l-1,the degradation efficiency of TC decreased.The initial p H had no significant effect on the degradation of TC.The intermediate products were determined by UV–vis spectrophotometry and ESI(+)–MS,and the degradation mechanism was analyzed.The reactive species,including O_(3),·OH,and H_(2)O_(2),etc.,produced in the plasma/catalyst system attracted electron-rich functional groups(amino group,aromatic ring,and double bond).Therefore,the gas–liquid plasma/catalyst system could be an effective and promising method for pharmaceutical wastewater treatment in future.
基金the National Science and Technology Major Project of China(No.2016ZX05028-004-003).
文摘Dedicated experiments and numerical simulations have been conducted to investigate the splitting characteristics of a gas-liquid two phase flow at a T junction.The experiments were carried out for different gas-liquid velocities.The flow rates in the two branches were measured accurately to determine how the two considered phases distribute in the two outlets.The experimental results have shown that when the two outlet pressures are asymmetric,the two-phase flow always tends to flow into the outlet which has a lower pressure.As the inlet liquid velocity increases,however,the two-phase flow gradually tends to split evenly.Compared with the experiment results,the pressure difference between the two outlets can be determined more accurately by means of numerical simulation.The trends of experimental results and simulations are in very good agreement.
基金Supported by the National Natural Science Foundation of China and SINOPEC
文摘The hysteresis of gas-liquid mass transfer rate and the corresponding radial liquiddistribution in a trickle bed reactor are measured to provide evidence for the correlation between thesetwo behaviors.Experimental results indicate that the hysteresis of gas-liquid mass transfer originatesfrom the nonuniformity of the hydrodynamic state of gas-liquid flow and the radial maldistributionof local k<sub>gia</sub> corresponds very well to the radial maldistribution of liquid flow in the bed.The localliquid flow rate is also found to be nonuniform in the azimuthal direction.In view of maldistributedliquid flow even in the pulsing flow regime,the conventional plug flow model seems oversimplifiedfor describing the behavior of a trickle bed.
基金the National Natural Science Foundation of China (No.20476072)
文摘Real-time laser holographic interferometry was applied to measure liquid concentrations of CO2 in the vicinity of gas-liquid free interface under the conditions of cocurrent gas-liquid flow for absorption of CO2 by ethanol. The influences of the Reynolds number on the measurable interface concentration and on the film thickness were discussed. The results show that CO2 concentration decreases exponentially along the mass transfer direction, and the concentration gradient increases as Reynolds number of either liquid or gas increases. CO2 concentrations fluctuate slightly along the direction of flow; on the whole, there is an increase in CO2 concentration. The investiga- tion also demonstrated that film thickness decreases with the increase of Reynolds number of either of the two phases. Sherwood number representing the mass transfer coefficient was finally correlated as a function of the hy- drodynamic parameters and the physical properties.
文摘1 INTRODUCTIONTrickle bed reactors are widely used in the process industry,particularly in petroleumhydroprocessing operations,and have been extensively studied by chemical engineers.In atrickle bed reactor,the gas and liquid flow cocurrently down through the packed bedand undergo chemical reactions.However,there exist multiple hydrodynamic stateswhich correspond to either uniform or,in most cases,nonuniform radial distributionof the gas and liquid flows in the packed section.Moreover,the hydrodynamic state
基金support of National Natural Science Foundation of China (No. 21577011)
文摘A double-chamber gas-liquid phase DBD reactor(GLDR), consisting of a gas-phase discharge chamber and a gas-liquid discharge chamber in series, was designed to enhance the degradation of benzene and the emission of NOx. The performance of the GLDR on discharge characteristics,reactive species production and benzene degradation was compared to that of the single-chamber gas phase DBD reactor(GPDR). The effects of discharge gap, applied voltage, initial benzene concentration, gas flow rate and solution conductivity on the degradation and energy yield of benzene in the GLDR were investigated. The GLDR presents a higher discharge power, higher benzene degradation and higher energy yield than that of the GPDR. NO2 emission was remarkably inhibited in the GLDR, possibly due to the dissolution of NO2 in water. The benzene degradation efficiency increased with the applied voltage, but decreased with the initial concentration, gas flow rate, and gas discharge gap, while the solution conductivity presented less influence on benzene degradation. The benzene degradation efficiency and the energy yield reached 61.11% and 1.45 g k Wh-1 at 4 mm total gas discharge gap, 15 k V applied voltage, 200 ppm benzene concentration,0.2 L min-1 gas flow rate and 721 μS cm-1 water conductivity. The intermediates and byproducts during benzene degradation were detected by FT-IR, GC-MS and LC-MS primarily, and phenols,COx, and other aromatic substitutes, O3, NOx, etc, were determined as the main intermediates.According to these detected byproducts, a possible benzene degradation mechanism was proposed.
基金This work was supported by the National Natural Science Foun-dation of China(51974349,U19B2012,51991363)the Natural Science Foundation of Shandong Province(ZR2017MEE057)which are gratefully acknowledged.
文摘To investigate the morphological evolution of the whole growth and aggregation processes of hydrate crystals near the gas–liquid interface,we used a high-pressure visual reactor with high-speed camera to capture the micromorphology of hydrate particles in a natural gas+pure water system with pressure from 2.6 to 3.6 MPa and sub-cooling from 4.7 to 6.23C.The results showed that under low sub-cooling conditions,the amount and size of particles increased first and then decreased in the range of 0–330 lm,and the small particles always dominated.These particles can be roughly classified into two categories:planar flake particles and polyhedral solid particles.Then,the concept of maximum growth dominant particle size was proposed to distinguish the morphological boundary of growth and aggregation.In addition,the micro model was established to better reflect the effects of particle formation process and evolution mechanism near the gas–liquid interface under stirring condition.The results of this study can provide a guidance for flow assurance in multiphase pipeline.
文摘Atmospheric pressure plasma technology is gaining increasing importance because it is a simple and tunable synthesis process for the production of metallic nanoparticles.In addition to the development of the power supply,improving the reactor is also one of the main strategies to enhanee the utility.In this study,a simple reactor for the gas-liquid discharge plasma induced by argon gas was applied to synthesize silver nanopailicles from silver nitrate(AgNO3)in solution.An AC power supply with a peak voltage of 3.5 kV was used.The frequency and on-time were set to 50 kHz and 2.5“s,respectively.The oscilloscope showed that the rising time was approximately 2“s.The ethanol was used as the source for the reactive reducing agent.No more additional comp on ents existed in the solution during the discharge and neither of the electrodes was in contact with the treated solution.The temperature in creased by 10°C within 1 min without a cooling system.Carbon was the main impurity and was expected to be produced from the decomposition of the organics under the plasma.The elevated temperature decreased the organic by-products by evaporation and could also decrease the production of carbon.Transmission electron microscopy showed that the spherical silver nanoparticles with a size of approximately 10 nm were synthesized with a crystal structure and that a low concentration of ethanol prefers the production of the mono-dispersed colloid.
基金Sponsored by the National Natural Science Foundation of China (Grant No.51006123)the Fundamental Research Funds for the Central Universities (Grant No.14CX05028A)
文摘In order to eliminate mal-distribution and ensure the side arm to produce desirable gas quality a special distributor is proposed. The experimental distributor mainly consists of a straight through section,a gas extraction line,a liquid extraction line and a side arm branch. A gas orifice and a liquid orifice are mounted at the gas and liquid extraction line respectively to control the outlet gas quality. The diameter of the liquid orifice was set to 2. 50 mm and three gas orifices with different size( dG= 2. 65,5. 00,10. 00 mm) were tested. The experiments were carried out at an air-water two-phase flow loop. The gas superficial velocity ranged from 6. 0 to 20. 0 m /s and the liquid superficial velocity was in the range of 0. 02- 0. 18 m /s. Flow patterns such as wave flow,slug flow and annular flow were observed. The gas quality of the side arm branch was found mainly determined by the flow area ratio of the gas orifice to the liquid orifice and independent of gas and liquid superficial velocity,flow patterns and extraction flux.
基金This work was supported by the Guangdong Basic and Applied Basic Research Foundation(2019A1515111116)Key R&D Program of Shandong Province(Nos.2019GSF109051,2019GGX101030)+1 种基金Shandong Provincial Postdoctoral Innovation Project(No.201902002)Foundation of Shandong University for Young Scholar’s Future Plans.
文摘The flow patterns and the void fraction related to a gas-liquid two-phase flow in a small channel are experimentally studied.The test channel is a transparent quartz glass circular channel with an inner diameter of 6.68 mm.The working fluids are air and water and their superficial velocities range from 0.014 to 8.127 m/s and from 0.0238 to 0.556 m/s,respectively.The void fraction is determined using the flow pattern images captured by a high-speed camera,while quick closing valves are used for verification.Four flow patterns are analyzed in experiments:slug flow,bubbly flow,annular flow and stratified flow.For intermittent flows(bubbly flow and slug flow),the cross-sectional void fraction is in a borderline condition while its probability distribution function(PDF)image displays a bimodal structure.For continuous flows(annular flow and stratified flow)the cross-sectional void fraction behaves as a fluctuating continuous curve while the(PDF)image displays a single peak structure.The volumetric void fraction data are also compared with available predictive formulas,and the results show that the agreement is very good.An effort is also provided to improve the so-called Gregory and Scott model using the available data.
文摘In the paper, a dynamical model of gas-liquid mixture motion through a pipeline with regard to change of rheological properties that occur as a result of heat-exchange process, is constructed, and the solutions of the obtained connected differential equations are given. Analytic expression allowing to determine pressure change along the length of a pipeline, is obtained.
文摘Liquid film cooling as an advanced cooling technology is widely used in space vehicles.Stable operation of liquid film along the rocket combustion inner wall is crucial for thermal protection of rocket engines.The stability of liquid film is mainly determined by the characteristics of interfacial wave,which is rarely investigated right now.How to improve the stability of thin film has become a hot spot.In view of this,an advanced model based on the conventional Volume of Fluid(VOF)model is adopted to investigate the characteristics of interfacial wave in gas-liquid flow by using OpenFOAM,and the mechanism of formation and development of wave is revealed intuitively through numerical study.The effects from gas velocity,surface tension and dynamic viscosity of liquid(three factors)on the wave are studied respectively.It can be found that the gas velocity is critical to the formation and development of wave,and four modes of droplets generation are illustrated in this paper.Besides,a gas vortex near the gas-liquid interface can induce formation of wave easily,so changing the gas vortex state can regulate formation and development of wave.What’s more,the change rules of three factors influencing on the interfacial wave are obtained,and the surface tension has a negative effect on the formation and development of wave only when the surface tension coefficient is above the critical value,whereas the dynamic viscosity has a positive effect in this process.Lastly,the maximum height and maximum slope angle of wave will level off as the gas velocity increases.Meanwhile,the maximum slope angle of wave is usually no more than 38°,no matter what happens to the three factors.
