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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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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： NUMERICAL-SIMULATION STRONG SHOCKS flowS MODEL SCHEMES CONNECTION

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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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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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A novel design of the collector's cover of solar induced convection power plant

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International Solar Energy Society Solar World Congress 2007, ISES 2007

作者： Li, Ping Mei, Danhua Li, Zaoyang Chen, Weixiong Zhang, Yongzhi Zhao, Liang School of Energy and Power Engineering 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 Induced Convection Power Plant is a technology of new energy using. It has a very broad perspective. However, the efficiency of the technology not so acceptable. This paper focuses on improving the efficiency of the technology. The thermal physical properties of common glass, polycarbonate and polycarbonate with CO2 ware compared in this paper to study the superiority and scientificity of polycarbonate with CO2. The results show that, the heat transfer coefficient of polycarbonate with CO2 is the smallest so that it has the best effect of warm-keeping. and it can improve the efficiency of the system to large extent. According to the study, the polycarbonate with CO2 is the best one for solar radiation to go through and it is not easy for Far Infrared ray to do that. Base on the results and other advantages of the polycarbonate with CO2, we conclude that polycarbonate with CO2 is the best choice for the material of the slope solar collector cover.

关键词： Polycarbonates

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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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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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Experimental study of heat transfer of ultra-supercritical pressure water in vertical upward internally ribbed tube

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High Technology Letters 2007年第1期13卷 17-22页

作者：王为术 Chen Tingkuan Luo Yushan　 Gu Hongfang Yin Fei National Key Laboratory of Multiphase Flow in Power Engineering Xi＇ an Jiaotong University Xi＇ an 710049 P.R. China School of Power Electric North China Institute of Water Conservancy and Hydroelectric Power Zhengzhou 450011 P.R. China

Under ultra-supercritical pressure, the heat transfer characteristics of water in vertical upward 4- head internally ribbed tubes with a diameter of 28.65mm and thickness of 8mm were experimentally studied. The experiments were performed at P = 25- 34MPa, G = 450- 1800kg/（m^2·s） and q = 200 600kW/m^2. The results show that the pressure has only a moderate effect on the heat transfer of uhra-supercritical water when the water temperature is below the pseudocritical point. Sharp rise of the wall temperature near the pesudocritical region occurs earlier at a higher pressure. Increasing the mass velocity improves the heat transfer with a much stronger effect below the pesudocritical point than that above the pesudocritical point. For given pressure and mass velocity, the inner wall heat flux also shows a significant effect on the inner wall temperature, with a higher inner wall heat flux leading to a higher inner wall temperature. Increasing of inner wall heat flux leads to an early occurrence of sharp rise of the wall temperature. Correlations of heat transfer coefficients are also presented for vertical upward internally ribbed tubes.

关键词： heat transfer supercritieal ultra-supereritieal vertical upward internally fibbed tube

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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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