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Measurement of Interfacial Area Transport in Oil‐water Dispersed flow by Double‐sensor Probe

AIP Conference Proceedings 2007年第1期914卷 328-334页

作者： Dongjian Zhao Xiaowei Hu Liejin Guo Ximin Zhang State Key Laboratory of Multiphase Flow Xi’an Jiaotong University Xi’an China

The double‐sensor conductivity probe was designed and applied to measure the distribution and transport characteristics of the oil‐water dispersed flow in a vertical upward pipe. Typical radial profiles of interfacial area concentration, oil phase fraction, interfacial velocity, and oil drop Sauter mean diameter were obtained at four axial locations from the test section entrance of z/D =8.75, 33.75, 58.5 and 80.5. The results showed that under most flow conditions, the radial profiles of interfacial area concentration, oil phase fraction and interfacial velocity at the first measuring location were more flat than those at other three locations. This is because the initial size of oil drops were mainly determined by the mixing chamber and the flow of oil‐water dispersion were far from fully‐development. The interfacial area transport mechanism was also discussed in details.

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New revised correlation to predict pressure drop for oil-gas two-phase flow through horizontal pipe

New revised correlation to predict pressure drop for oil-gas...

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International Petroleum Technology Conference 2007, IPTC 2007

作者： Liu, Wenhong Guo, Liejin Zhang, Ximin Lin, Kai Yang, Long Feng, Yaorong Tubular Goods Research Center of CNPC Key Laboratory for Mechanical and Environmental Behavior of Tubular Goods China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University China

ISBN: (纸本)9781615673360

An experimental investigation on oil-gas two-phase flow through a straight horizontal plexiglas pipe within 40mm inner diameter was conducted. The superficial velocity ranges of oil and air were 0.05-0.612m/s and 0.024-50.64m/s, respectively. The atmospheric temperature condition was maintained throughout the *** frictional pressure drop multiplier of two-phase flow was expressed using the Lockhart-Martinelli parameter correlation in accordance with typical flow pattern, but the modification factor C in the correlations was defined afresh according to flow conditions. New predict correlations for pressure gradient in accordance with typical flow patterns were proposed and the mechanisms of pressure drop production were analyzed for each flow patterns. The proposed models give a good agreement with the experimental data. Copyright 2007, International Petroleum Technology Conference.

关键词： Two phase flow

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Simulation of constant wall-temperature heat transfer in microchannel by Direct Simulation Monte Carlo Method

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Jisuan Lixue Xuebao/Chinese Journal of Computational Mechanics 2007年第6期24卷 817-822页

作者： Yan, Xiao-Hong Wang, Qiu-Wang Suo, Xiao-Na Xie, Gong-Nan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Pressure-driven gaseous flow in microchannel under constant wall-temperature boundary condition was simulated with Direct Simulation Monte Carlo (DSMC) method. The velocity and temperature distributions were presented for different wall temperatures and different ratios of microchannel length to height. The simulation results show that;Compressibility plays an important role on the temperature distributions and the actual temperature distributions are affected by both compressibility and heat transfer condition. The streamwise distribution of gas temperature may decrease when the gas is heated by the wall due to significant compressibility in short microchannel. When the gas is heated by wall, the pressure gradient increases and the profile of streamwise velocity becomes raised near the channel entrance. The cross-sectional averaged velocity decreases in the case of Kn = 0.055 and increases in another case of Kn = 0.88. The variation of friction factor with the wall temperature is distinct when gas flows in slip and transition regions.

关键词： Microchannels

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Hydrogen production from sludge in supercritical water and its energy evaluation

Hydrogen production from sludge in supercritical water and i...

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5th International Energy Conversion Engineering Conference

作者： Qinming, Zhang Shuzhong, Wang Liang, Wang Donghai, Xu Lingling, Lu State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Department of Thermal Engineering Xi'an Jiaotong University AIAA

ISBN: (纸本)1563479028

Gasification of high moisture content biomass in supercritical water has been identified as a promising alternative system for producing renewable hydrogen. Supercritical water partial oxidation is the process by which an oxidant appears during the reaction. The key advantage of this process is the rapid heating of the gasification medium, resulting in less char formation and improved hydrogen yield. Many researchers have studied the supercritical water gasification of model compounds. However, real biomass which is of importance for large production of hydrogen has yet to be thoroughly examined. In this paper, gasification of high moisture content municipal sludge was studied in a continuous reactor employing hydrogen peroxide as an oxygen source. The reaction was tested across temperatures and pressures in the range of 673 to 873 K and 24 to 30 MPa, and across various residence times ranging from 3 to 15 minutes. We found that sludge at low concentrations can be completely gasified with no observable char or tar formation. The improvement of gasification efficiency by partial oxidation was accompanied with a high yield of hydrogen and carbon monoxide. Through this, we evaluated the energy efficiency of sludge gasification. Our thermodynamic calculations show that the energy efficiency reaches 50% when considering hydrogen, carbon monoxide, and methane as the valuable gases in the ideal case. Taking into account the energy recovery from the hot water at 30 MPa and 873 K and assuming the ideal scenario of no external heat loss, the overall energy yield potentially reaches 85%. Our results show that the key mechanism of the gasification process is energy recovery, as the chemical reaction is endothermic and requires high temperatures.

关键词： Hydrogen production

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New Method of Online Measurement of Oil and Suspended Material Concentration In flowing Waste Water

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AIP Conference Proceedings 2007年第1期914卷 215-220页

作者： Hongwei Liao Guobing Xu Xinqiang Xu Fangde Zhou Key State Laboratory of Multiphase Flow and Power engineering Xian Jiaotong University Xian China

At present, the most of the measurements of oil and suspended material concentration in waste water measuring are not online surveys. A new method of online measurement of oil and suspended material concentration in flowing waste water is presented. The room experiments and field tests showed that it is suitable to waste water treatment on line. After sampling, It needed to measure immediately the concentration in first time. Then let sample to be in still in 10 – 20 seconds. After that the bulk concentration was measured in second time. Because of the suspended solids having heavy density, they would be dropped from waster water. During ultrasonic operation, emulsify the oil in waster water, the oil and suspended solid would be depart. After that the third time measurement was done. In thus way the concentrations of oil and suspended solids can be measured. At present there are two on‐site equipments operating in the Changqing oilfield, and the results are pretty well.

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Stability of Stratified Gas-Liquid flow in Horizontal and Near Horizontal Pipes

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Chinese Journal of Chemical Engineering 2007年第5期15卷 619-625页

作者：顾汉洋郭烈锦 State Key Laboratory of Multiphase Flow Xi＇an Jiaotong University Xi＇an 710049 China School of Nuclear Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China

A viscous Kelvin-Helmholtz criterion of the interfacial wave instability is proposed in this paper based on the linear stability analysis of a transient one-dimensional two-fluid model. In thismodel, the pressure is evaluated using the local momentum balance rather than the hydrostatic approximation. The criterion predicts well the stability limit of stratified flow in horizontal and nearly horizontal pipes. The experimental and theoretical investigation on the effect of pipe inclination on the interfacial instability are carded out. It is found that the critical liquid height at the onset of interfacial wave instability is insensitive to the pipe inclination. However, the pipe inclination significantly affects critical superficial liquid velocity and wave velocity especially lor low gas velocities.

关键词： two-fluid model Kelvin-Helmholtz criterion interfacial instability gas-liquid stratified flow

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Coupled double-distribution-function lattice Boltzmann method for the compressible Navier-Stokes equations

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Physical Review E 2007年第5期76卷 056705-056705页

作者： Q. Li Y. L. He Y. Wang W. Q. Tao State Key Laboratory of Multiphase Flow School of Energy and Power Engineering Xi’an Jiaotong University Xi’an Shaanxi 710049 China

A coupled double-distribution-function lattice Boltzmann method is developed for the compressible Navier-Stokes equations. Different from existing thermal lattice Boltzmann methods, this method can recover the compressible Navier-Stokes equations with a flexible specific-heat ratio and Prandtl number. In the method, a density distribution function based on a multispeed lattice is used to recover the compressible continuity and momentum equations, while the compressible energy equation is recovered by an energy distribution function. The energy distribution function is then coupled to the density distribution function via the thermal equation of state. In order to obtain an adjustable specific-heat ratio, a constant related to the specific-heat ratio is introduced into the equilibrium energy distribution function. Two different coupled double-distribution-function lattice Boltzmann models are also proposed in the paper. Numerical simulations are performed for the Riemann problem, the double-Mach-reflection problem, and the Couette flow with a range of specific-heat ratios and Prandtl numbers. The numerical results are found to be in excellent agreement with analytical and/or other solutions.

关键词： Computational methods

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Orientation-dependent Hydrodynamic Instabilities from Chemo-Marangoni Cells to Large Scale Interfacial Deformations

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Chinese Journal of Chemical Engineering 2007年第5期15卷 748-753页

作者：石英 Kerstin Eckert State Key Laboratory of Multiphase Flow in Power Engineering Xi＇an Jiaotong University Xi＇an 710049 China Institute for Aerospace Engineering Technische Universitat Dresden D-01062 Dresden Germany

The interplay between chemistry and interfacial-tension-driven hydrodynamic instabilities has been studied experimentally. The system on hand consists of two immiscible liquids separated along an initially plane interface at which an interfacial reaction takes place to produce in situ a surfactant. It is identified that the dynamics of the system depends on the orientation of the Hele-Shaw cell with respect to the vector of gravity. If the nele-Shaw cell is placed vertically, Marangoni cells with vigorous convection develop in both phases along a nearly planar interface. However, if the Hele-Shaw cell is tilted off the gravity, the instabilities in the system are characterized by the large scale interracial deformation with a spatio-temporal periodicity together with the chemo-Marangoni convection. The focus is on the exploration of the transition from the cellular mode to the large scale interfacial deformation.

关键词： interfacial reaction in situ produced surfactant Marangoni convection interfacial deformation

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A New Measuring Method of Oil‐water‐gas Three Phase flowrate by Using of Heat Transfer and Fluid Dynamics

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AIP Conference Proceedings 2007年第1期914卷 221-225页

作者： Hongwei Liao Siyi Zhou Lei Liu Fangde Zhou Key State Laboratory of Multiphase Flow In Power engineering Xian Jiaotong University Xian. China

It is so difficult to measure individual flowrates of oil‐water‐gas three phase on‐line that very few real three phase flowmeters have been developed in the world. This paper presents a new measuring method of oil‐water‐gas three phase flowrate by using of heat transfer and fluid dynamics. A cylindrical cyclone is used to separating the most of natural gas from oil‐water‐gas three phase mixture. A flow mixer is used to homogenize oil and gas flow in a short distance for measurement of bulk flow velocity. A venture‐tube is used to measure overall flowrate of three phase mixture. An inverse‐U tube is used to measure gas fraction. The heat transfer way is used to measure water fraction. No radiation method is used. So this kind of flowmeter is much more safety, and has much more accuracy. Many room and field experiments have been done. The test results done by the Test Institute of Petroleum Industry of Daqing Oil Field Construction & Design Research Institute were quite well. This kind of three phase flowmeter has been widely used in many oil fields.

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Experimental study on optical properties of the collector

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International Solar Energy Society Solar World Congress 2007, ISES 2007

作者： Wang, Juan Zhao, Liang Li, Huashan School of Science Xi'an Jiaotong University P.O. Box 2264 Xi'an 710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

ISBN: (纸本)9781622765447

Solar collector is one of the most important parts of solar chimney power plant. It plays an important role in improving the efficiency and saving the cost of the whole system. In this paper, several transparent materials which could be used as the collector were chosen to study the optical properties. The materials include polymethyl methacrylate (PMMA), polycarbonate (PC), perspex (PS) and ordinary glass. Firstly, an experiment device was designed with the collector angles varying from 15° to 60°. Secondly, different thickness of glass and different slope angles of the collector of these materials mentioned above on transmittance was compared. The effect of pollutions caused by the natural environment such as dust, rain and aging on these materials was considered in the experiment. Based on the experimental results, a conclusion was made that PMMA has the highest transmittance among the four materials without considering other factors.

关键词： Optical properties

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