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Brownian Dynamics Simulation of Microstructures and Elongational Viscosities of Micellar Surfactant Solution

Chinese Physics Letters 2008年第12期25卷 4469-4472页

作者：魏进家 KAWAGUCHI Yasuo 宇波李凤臣 State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 Department of Mechanical Engineering Faculty of Science and Technology Tokyo University of Science Noda Chiba 2788-510 Japan Beijing Key Laboratory of Urban Oil and Gas Distribution Technology China University of Petroleum (Beijing) Beijing 102249 School of Energy Science and Engineering Harbin Institute of Technology Harbin 150001

Brownian dynamics simulation is conducted for a dilute surfactant solution under a steady uniaxial elongational flow. A new inter-cluster potential is used for the interaction among surfactant micelles to determine the micellar network structures in the surfactant solution. The micellar network is successfully simulated. It is formed at low elongation rates and destroyed by high elongation rates. The computed elongational viscosities show elongation- thinning characteristics. The relationship between the elongational viscosities and the mierostructure of the surfactant solution is revealed.

关键词： field emission molybdenum dioxide enhancement factor

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Available energy analysis of new tandem double-capillary tube refrigeration system for refrigerator-freezers

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Frontiers of Energy and Power Engineering in China 2008年第1期2卷 36-42页

作者： Maogang, He Xinzhou, Song Ying, Zhang Jiantao, Zhang State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 China Henan Xinfei Electric Co. Ltd. Xinxiang 453002 China

A new tandem double-capillary tube refrigeration system for refrigerator-freezers is proposed. A capillary tube was added between the two evaporators in the fresh and frozen food storage chests to raise the evaporation temperature of the refrigerating chamber, and reduce the heat exchange temperature difference and the available energy loss. Peng-Robinson (P-R) equation of state was adopted to calculate the thermodynamic properties of the refrigerants, and the available energy analysis of the vapor compression refrigeration cycle was programmed to calculate the thermodynamic performances of the new and the conventional refrigeration cycle of the refrigerator-freezer. The calculation results show that the available energy efficiency of the conventional refrigeration cycle of the refrigerator-freezer is 21.20% and 20.57%, respectively when the refrigerant is R12 and R134a, while that of the double-capillary tube refrigeration cycle of the refrigerator-freezer is 23.97% and 23.44%, respectively. By comparison, the available energy efficiency of the new refrigeration system increases by 13.07% and 13.95%, respectively. © 2008 Higher Education Press and Springer-Verlag.

关键词： Available energy analysis Chest refrigerator Double-capillary tube Pyrology

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Experimental Investigation of Slug Development on Horizontal Two-phase flow

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Chinese Journal of Chemical Engineering 2008年第2期16卷 171-177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

Slug initiation and subsequem evolution along a 5.0 cm ID, 16m long horizomal pipe are experimentally studied. The transient characteristics of interfacial structures are described by using simultaneous measuremeres of the liquid height at multiple locations along the pipe. Various effects of superficial gas and liquid velocities and pressure oscillation on the slug initiation and evolution along the pipe are illustrated. It is found that the slug is initiated by a deterministic orocess with reolenishmem and deoletion of liquid near the inlet for the superficial gas velocity USG〈3.0m·s^-1 and by a stochastic process with wave coalescence along the pipe for USG〉3.0m·s^-*** evolution of the slugs is strongly attected by superhclal gas and liquid veloclties for USG〈3.0m·s^-1 but weakly affected by the superficial gas velocity for USG〉3.0 m·s . The suppression of pressure oscillation at the pipe inlet significantly delays the onset of slugging, with slugs forming postponed further downstream. The slug frequency at the outlet is, however, not affected by the variation in the pressure oscillation.

关键词： gas-liquid slug flow slug initiation and evolution slug frequency

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Experimental investigation on the conversion of nitrogenous gas products during coal pyrolysis

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Journal of Fuel Chemistry and Technology 2008年第2期36卷 134-138页

作者： Hai-feng LIU Yin-he LIU Yan-hua LIU De-fu CHE State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The conversion of nitrogenous gas products during coal pyrolysis is investigated in a drop tube reactor. Four raw coals and two demineralized coals have been used for pyrolysis at 500°C, 700°C, 900°C and 1100°C. The results indicate that the yields of N 2 and NO precursors, such as HCN and NH 3 , increase with increasing temperature. Coal type has significant effect on the yield of nitrogenous gas products. For lower rank coal, the conversion of fuel nitrogen is higher. Majority of fuel nitrogen in high rank coals is built into condensed aromatic structures to form Char-N. The mineral matters in coal can promote the conversion of fuel nitrogen to N 2 , but they can also suppress the conversion of fuel nitrogen to HCN and NH 3 .

关键词： coal pyrolysis HCN NH 3 N 2

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Research and application of flow visualization technique in large-scale hydraulic models

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Journal of Physics: Conference Series 2009年第1期147卷

作者： Wen Cheng Bao-wei Hu Tian Wan Zhang-bin Wang Fujio Yamamoto State Key Laboratory of Multiphase Flow in Power Engineering Key Laboratory of Northwest Water Resources and Environmental Ecology of Education Ministry ShaoXing University Shao Xing 312000 China Fiber Amenity Engineering Course Graduate School of Engineering University of Fukui Bunkyo 3-9-1 Fukui 910-8507 Japan Xian Jiao tong University Xian 710049 China Xian University of Technology Xian 710048 China

With the rapid development of computer and optical technique, as a powerful measuring method in hydrodynamics, flow visualization technique is able to get much flow field information in practical engineering. It also has an important meaning to projects and environmental areas. The image processing is the key to flow visualization for gaining flow field information. In terms of the PIV principles, the algorithm of PIV based on Fast Fourier Transformation (FFT) is studied, and the image mosaic program based on genetic algorithm has been compiled. The flow field of seabuckthorn flexible dam has been calculated and analyzed by using those methods as above-mentioned, and in the meanwhile, the application of flow visualization technique to measure the outdoor flow field has been studied exploringly, which proves that it is feasible to apply this technique to measure the large-scale outdoor flow field.

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Theoretical model for interfacial structure in bubble slug

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Shanghai Jiaotong Daxue Xuebao/Journal of Shanghai Jiaotong University 2008年第6期42卷 1009-1012+1016页

作者： Gu, Han-Yang Guo, Lie-Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China School of Nuclear Science and Engineering Shanghai Jiaotong University Shanghai 200240 China

Slug flow is a highly intermittent flow regime in which large bubble slugs flow alternately with liquid slugs at randomly fluctuating frequency. A one-dimensional model for the interfacial structure in bubble slug was developed based on mass and momentum conservation for bubble nose, body and tail as well as for a hydraulic jump at the rear of the bubble. The model can reproduce experimental results accurately. The results indicate that the interfacial structure is strongly dependent on the Froude number defined by gas/liquid mixture velocity, pipe inclination, and bubble length.

关键词： Gas-liquid flow Interfacial structure One-dimensional model

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An Efficient Segregated Algorithm for Incompressible Fluid flow and Heat Transfer Problems - IDEAL (Inner Doubly Iterative Efficient Algorithm for Linked Equations) Part II: Application Examples

引用

Numerical Heat Transfer: Part B -- Fundamentals 2008年第1期53卷 18-38页

作者： Sun, D. L. Qu, Z. G. He, Y. L. Tao, W. Q. wqtao@*** State Key Laboratory of Multiphase Flow in Power Engineering School of Energy & Power Engineering Xi''an Jiaotong University Xi''an Shaanxi People''s Republic of China

In this article, comprehensive comparisons are made between the SIMPLER and IDEAL algorithms for four application examples. It is found that the IDEAL algorithm is efficient and stable not only for the simple, low-Re/Ra or coarse-mesh flow cases, but also for the complex, high-Re/Ra or fine-mesh flow cases. For the low-Re/Ra, coarse-mesh flow cases, the ratio of CPU time of IDEAL to that of SIMPLER ranges from 0.029 to 0.7. For the high-Re/Ra, fine-mesh flow cases, the IDEAL algorithm can obtain convergent results but the SIMPLER algorithm cannot, even though the underrelaxation factors are adjusted. [ABSTRACT FROM AUTHOR]

关键词： ALGORITHMS HEAT transfer FLUID mechanics FLUID dynamics HYDRODYNAMICS

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A parametric study to design an effective spray cooling deployment in an entrained-flow coal gasifier

A parametric study to design an effective spray cooling depl...

引用

25th Annual International Pittsburgh Coal Conference, PCC

作者： Wang, Qiu Liu, Peiyao Xu, Shisen Wang, Baomin Wang, Ting State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi China Thermal Power Research Institute Xi'an Shaanxi China Energy Conversion and Conservation Center University of New Orleans New Orleans LA 70148 United States

ISBN: (纸本)189097725X

Gasification is a clean technique that converts coal into syngas, which can be cleaned much more easily than the coal itself. The raw sysgas exiting the gasifier is usually at a very high temperature. To protect the rearward equipment, the raw syngas needs to be cooled to allow appropriate cleaning of particulates, ashes, and sulfur before it exits the gasifier. Cooling of the syngas can be performed by employing heat exchangers or direct spray cooling. This paper focuses on conducting a 3-D CFD parametric study to aid in the design of an effective water spray cooling deployment. The studied parameters include water droplet sizes (100400m) and water injection angles. The goal is to cool the syngas from 1550C to 800C using the shortest spray section. The gasifier is designed to produce methanol at a full load condition, so the amount of sprayed water is fixed to ensure the syngas composition meets the specifications for methanol production. The gasifier is steam-oxygen blown with dry coal feed using approximately 960 tons per day. The results reveal that smaller droplets are effective in reducing the cooling section length. Moreover, using three water injection angles show that inclining the spraying angle upward 45 degrees could shorten the effective cooling length. This study provides a guide for cutting the cost of manufacturing a gasifier cooling section.

关键词： Coal

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Analysis of impedance with different discharge current in proton exchange membrane fuel cell

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Hsi-An Chiao Tung Ta Hsueh/Journal of Xi'an Jiaotong University 2008年第5期42卷 622-625页

作者： Shang, Dehua Ma, Bin Zhang, Guangsheng Guo, Liejin Liu, Hongtan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Department of Mechanical Engineering University of Miami Coral Gables FL 33124 United States

Considering the fact that proton exchange membrane (PEM) fuel cell has different impedance performances under different discharge currents, a PEM fuel cell with single serpentine flow field was investigated with electrochemical impedance spectroscopy, and the R (QR) equivalent circuit was used to calculate the circuit element parameters. The experimental results show that water in the fuel cell increases from insufficient to sufficient and then excessive with the increasing discharge current. Accordingly, the electrochemical reaction rate on the electrodes increases first and then decreases, thus the charge transfer resistance decreases and then increases. The impedance of PEM fuel cell increases obviously for high discharge currents due to the accessional impedance produced by double-layer effect, while the impedance reaches minimum at medium discharge current (5 A).

关键词： Proton exchange membrane fuel cells (PEMFC)

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Synthesis of Biodiesel from Soybean Oil and Methanol Catalyzed by Cationic Ion-exchange Resin in an Ultrasonic Reactor

Synthesis of Biodiesel from Soybean Oil and Methanol Catalyz...

引用

The 12th Asian Pacific Confederation of Chemical Engineering Congress

作者： B.Yang Bolun Department of Chemical Engineering State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong University Xi'an Shaanxi 710049China

Biodiesel is generally produced by the transesterification of vegetable oils or animal fats com- posed of C-C fatty acid triglycerides with methanol under the presence of a catalyst. The conventional biodiesel product... 详细信息

关键词： pharmaceutical synthesis green chemistry green engineering solvent selection

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