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

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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Measurement of current distributions in a PEM fuel cell with interdigitated flow Fields

Measurement of current distributions in a PEM fuel cell with...

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7th Symposium Devoted to Proton Exchange Membrane Fuel Cells - 212th ECS Meeting

作者： Zhang, G.S. Ma, B. Shang, D.H. Guo, L.J. Sun, H. Liu, H.T. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China Department of Mechanical and Aerospace Engineering University of Miami Coral Gables FL 33124 United States Electrochemical Society

ISBN: (纸本)9781566775823

Current distributions in a PEM fuel cell with interdigitated flow fields were measured with the current distribution measurement gasket technique. The measurement results showed that current density distribution in a fuel cell with interdigitated flow fields is much more uniform than those observed in a fuel cell with serpentine flow fields, especially at low reactant gas flows. The more uniform current distribution can be attributed to more uniform flow distribution over the flow fields. Measurement results also showed that interdigitated flow fields have very good water removal capability and no flooding phenomena were observed at high humidification temperatures;while at low humidification temperatures, the effect of drying is more severe than that found in serpentine flow fields. © The Electrochemical Society.

关键词： Proton exchange membrane fuel cells (PEMFC)

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Design of High-Order Difference Scheme and Analysis of Solution Characteristics - Part II: A Kind of Third-Order Difference Scheme and New Scheme Design Theory

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Numerical Heat Transfer: Part B -- Fundamentals 2007年第3期52卷 271-295页

作者： Jin, W. W. Tao, W. Q. wqtao@*** State Key Laboratory of Multiphase Flow in Power Engineering School of Energy &Power Engineering Xi''an Jiaotong University Xi''an People''s Republic of China

In this Part II, on the basis of the general style design of second-order difference scheme and the analysis of the absolutely stable scheme proposed in Part I, the companion article, the general design method of any high-order difference scheme is proposed. Based on this method, a new kind of third-order difference scheme including 17 different variants is constructed, which uses the same grid points as existing second-order difference schemes but is different from them in that the grids are chosen symmetrically from two sides of the interface. Because they have the same matrix style created by the same grid plots of the discretization equation, these third-order schemes require the same CPU time and memory as the second-order schemes; however, this kind of symmetrical third-order difference scheme will keep the consistency between the false diffusion and the stability, and the stability of the scheme is better than that of the existing biased second-order scheme. Further research shows that under the conditions of matrix style and computer memory, the scheme constituted by symmetrically numbered grids from two sides of the interface with odd order of accuracy can maintain consistency between numerical accuracy and stability better than any kind of scheme designed according to the 'upwind' idea. Based on this understanding, a new scheme design theory called symmetric and odd-order accuracy scheme design theory is proposed. [ABSTRACT FROM AUTHOR]

关键词： power (Mechanics) NUMERICAL analysis HEAT transfer multiphase flow NUMERICAL calculations

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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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An efficient and robust numerical scheme for the SIMPLER algorithm on non-orthogonal curvilinear coordinates: CLEARER

An efficient and robust numerical scheme for the SIMPLER alg...

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作者： Cheng, Y.P. Lee, T.S. Low, H.T. Tao, W.Q. Laboratory of Fluid Mechanics Department of Mechanical Engineering National University of Singapore Singapore Singapore State Key Laboratory of Multiphase Flow in Powering Engineering School of Energy and Power Engineering Xian Shaanxi China Laboratory of Fluid Mechanics Department of Mechanical Engineering National University of Singapore 119260 Singapore Singapore

In this article, an Improved SIMPLER (CLEARER) algorithm is formulated to solve the incompressible fluid flow and heat transfer on the nonstaggered, nonorthogonal curvilinear grid system. By virtue of a modified momentum interpolation method in calculating the interface contravariant velocity in both the predictor step and the corrector step, the coupling between pressure and velocity is fully guaranteed, and the conservation law is also satisfied. A second relaxation factor is introduced in the corrector step, of which the convergent solution is independent. By setting the second relaxation factor less than the underrelaxation factor for the velocity to some extent, both the convergence rate and robustness can be greatly enhanced. Meanwhile, the CLEARER algorithm can also overcome the severe grid nonorthogonality. With the simplified pressure-correction equation, the convergent solution can still be obtained even when the intersection angle among grid lines is as low as 1, which may provide valuable guidance in studying the fluid flow in complex geometries.

关键词： Computational fluid dynamics

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Improvement of SIMPLER algorithm for incompressible flow on collocated grid system

Improvement of SIMPLER algorithm for incompressible flow on ...

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作者： Cheng, Y.P. Lee, T.S. Low, H.T. Tao, W.Q. Laboratory of Fluid Mechanics Department of Mechanical Engineering National University of Singapore Singapore Singapore State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an Shaanxi China Laboratory of Fluid Dynamics Department of Mechanical Engineering National University of Singapore 10 Kent Ridge Crescent 119260 Singapore Singapore

In this article an Improved SIMPLER (CLEARER) algorithm is proposed to solve incompressible fluid flow and heat transfer problems. Numerical study shows with the CLEARER algorithm on a collocated grid, in the correction stage the velocities on the main nodes are overcorrected with the pressure correction, which lowers the convergence rate;hence a second relaxation factor is introduced to overcome this disadvantage. By setting this factor less than the underrelaxation factor for velocities, the convergence performance can be significantly enhanced;meanwhile, the robustness can also be increased. Four numerical examples with reliable solutions are computed to validate the CLEARER algorithm, and the results show that this algorithm can predict the numerical results accurately. Compared with the SIMPLER algorithm, CLEARER can enhance the convergence rate greatly, and in some cases it only needs as little as 17% of the iterations required by SIMPLER to reach the same convergence criterion.

关键词： Incompressible flow

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Wire‐Mesh Capacitance Tomography in Gas‐Liquid flows

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AIP Conference Proceedings 2007年第1期914卷 710-716页

作者： Shan‐Fang Huang Xiu‐Gang Zhang Dong Wang Zong‐Hu Lin State Key Lab. of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

A new intrusive, wire‐mesh capacitance tomography for phase distributions in horizontal pipes is presented. A wire with an insulating film is used as a capacitor. The capacitance is in direct proportion to water film thickness, independent of water distribution and the salinity. We can obtain film thickness by measurement of capacitance. The sensor consists of four parallel wire capacitors, vertically placed over the cross section of the pipe. The interface is the result of linking the discrete film thicknesses with smooth curve, which are the tomographic result only when both phases are continuous. Static and dynamic experiments were carried out in air‐water two‐phase flows in horizontal pipes, from which we analyze the disturbance factors of the sensor to the flow field and measurement error of film thickness. The experimental results show that the tomographic results are consistent with expectation. The method has several advantages of no reconstructed algorithms, high signal‐to‐noise ratio, high sensitivity, and high spatio‐temporal resolution. The disturbance and error can be neglected in the range of this paper.

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multiphase flow Measurements by Full Stream Batch Sampling

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AIP Conference Proceedings 2007年第1期914卷 165-171页

作者： Dong Wang Fa‐Chun Liang Xiu‐Gang Zhang Zong‐Hu Lin State Key Lab. of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

A new method of multiphase flow measurements that based on the “extracting and separating method” was proposed in this paper. An extraction flow (or sample) is diverted in a manner of time sharing or full stream batch sampling, then the sample is separated into single phase flows and metered with conventional flow meters, the total flow rates of each phase are determined according to the metered values and the extraction ratios. Because the full stream is conducted to the extraction loop during sampling, no matter what the flow regime of multiphase flow is, the extracted stream (or sample) is always the representative of the total stream and the extraction ratio can keep stable. Experiments were conducted in an air‐water‐oil flow test loop, the inside pipe diameter of the test loop was 50 mm, and the superficial gas velocity varied from 4.5 m/s ∼22m/s, the liquid superficial velocity was in the range of 0.02∼0.3m/s, the oil concentration was in the range of 0.0%∼60% by volume. The flow pattern occurring during the experiments included stratified flow, wave flow and annular flow. The experimental results shown that the full stream batch sample method is feasible to measure the multiphase flow rate, and the average error of flow rates measurements for each phase was less than 3.82%.

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Numerical simulation of upward microbubble-laden turbulent channel flow

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Nanjing Hangkong Hangtian Daxue Xuebao/Journal of Nanjing University of Aeronautics and Astronautics 2007年第1期39卷 51-55页

作者： Xiong, Xianpeng Liu, Weihua Ang, Haisong Gao, Xiufeng Wei, Jinjia College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

To improve the predictive accuracy of bubble concentration distribution, numerical study of upward turbulent channel flows laden with microbubbles is carried out and the fluid-bubble two-way coupling interaction is considered. Direct numerical simulation is used for solving the Navier-Stokes equation and Lagrangian approach is used to track the bubble trajectories through the action of forces imposed by the fluid and the gravity. The forces acted on the bubbles are drag, virtual mass, lift, wall lift, pressure gradient, and gravity. Numerical results show that the bubble concentration distribution can be predicted by using the two-way coupling of the fluid and the bubble motion, and adding the wall lift force into the bubble motion equation, and the fluid velocity, turbulence intensity and shear stresses modified by the bubble motions can also be revealed.

关键词： Bubbles (in fluids)

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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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