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1st ASME Micro/Nanoscale Heat Transfer International Conference, MNHT08

作者： Wen-Quan, Tao Gui-Hua, Tang Ya-Ling, He Zhuo, Li State Key Laboratory of Multiphase Flow School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 China

ISBN: (纸本)0791842924

First the flow friction characteristics of nitrogen and helium in stainless steel microtubes, glass microtubes, square glass microchannels, and rectangular silicon microchannels are tested. The data in glass microtubes with diameters from 50 to 201 microns and in square glass channels with characteristic diameters from 52 to 100 microns show that the friction factors are in good agreement with the conventional predictions. The friction factors in stainless-steel tubes with diameters from 119 to 300 microns are much higher than the conventional ones. The results for two of the four silicon microchannels with characteristic diameters from 26-60 microns are in good agreement while those of the other two channels are larger. This discrepancy is resulted from the large relative surface roughness. Smaller friction factors in glass microtubes with diameters from 10 to 20 microns are obtained due to the rarefaction effect. Second the flow friction experimental data for deionized water flow in glass microtubes with diameters from 50 to 530 microns show that friction factors and transition Reynolds numbers are in good agreement with the conventional predictions. However, the friction factors in stainless steel microtubes with diameters from 50-1570 microns are much higher than the conventional predictions. This discrepancy is attributed to the large surface relative roughness or denser roughness distribution. Numerical simulations considering electroviscous effect are carried out. The simulation results show that the electroviscous effect does not play a significant role in the friction factor for channel dimensions of the order of microns though it does affect the velocity profile and hence it could be neglected in engineering applications for channel dimensions of the order of microns. Third the measured local Nusselt number distribution of deionized water along the axial direction of the stainless steel tubes of 373-1570 microns with uniform heat flux do not accord with th

关键词： Glass

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EXPERIMENTAL STUDY ON GAS-LIQUID TWO-PHASE flowS IN AN AREATION TANK BY USING IMAGE TREATMENT METHOD

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Journal of Hydrodynamics 2008年第5期20卷 650-655页

作者： CHENG Wen LIU Wen-hong HU Bao-wei WAN Tian State Key Laboratory of Multiphase Flow in Power Engineering Xi＇an Jiaotong University Xi＇an 710049 China Environment Research Institute Xi＇an University of Technology Xi＇an 710048 China Environment Research Institute Xi＇an University of Technology Xi＇an 710048 China

Particle Image Velocimetry （PIV） technique was employed to study experimentally gas-liquid two-phase flow in an aeration tank. In terms of the PIV principles, an algorithm of PIV based on the Fast Fourier Transformation （FFT） was worked out. The PIV program was developed and verified, and then was used to measure three kinds of states in the testing device. The program was also used to calculate and analyze the related parameters. The experimental data indicate that the bubbles in testing device have the longest resident time and stronger turbulent intensity for the gas-liquid two-phase flow in a special case （Case 3）, resulting in great increase of the oxygen transferring speed and efficiency, whereby providing the basis for the selection design of aeration tank.

关键词： gas-liquid two-phase flow Particle Image Velocimetry （PIV） Fast Fourier Transformation （FFT） aeration tank

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Preparation and characterization of ZnO/ZnS hybrid photocatalysts via microwave-hydrothermal method

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Frontiers of Environmental Science & engineering 2008年第4期2卷 415-420页

作者： Jinglian ZHAO Liang ZHAO Xinping WANG State Key Laboratory of Multiphase Flow in Power Engineering Department of Environmental EngineeringXi’an Jiaotong UniversityXi’an 710049China Department of Physics and Astronomy Rice UniversityHoustonTX 77005-1657USA

The photocatalytic performance of ZnO/ZnS hybrid nanocomposite was largely higher than that of the mere ZnO or ZnS nanoparticles,but the complicated procedure and misdistribution of final products limited its large-scale *** exploration of a novel synthesis route of ZnO/ZnS hybrid photocatalysts with high catalytic performance is becoming a crucial step for the large-scale application of ZnO/ZnS hybrid photocatalytic *** and characterization of nanosized ZnO/ZnS hybrid photocatalysts were studied in this *** photocatalysts were obtained via microwavehydrothermal crystallization with the help of sodium *** products were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),particle size distribution(PSD),and Fourier transformed infrared spectroscopy(FT-IR).The results indicated that so-synthesized ZnO/ZnS samples consisted of the high pure cubic(sphalerite)ZnS and hexagonal ZnO nanocrystallines with a narrow particle size *** possible formation mechanisms of ZnO/ZnS nanocrystallines were mainly attributed to the superficially protective effect of *** photocatalytic experiments demonstrated that the ZnO/ZnS photocatalysts exhibited a higher catalytic activity for the degradation of acid fuchsine than other monocomponents.

关键词： photocatalyst ZnO/ZnS sodium citrate hydrothermal microwave

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

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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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Combustion research in internal combustion engines and its challenges

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Neiranji Xuebao/Transactions of CSICE (Chinese Society for Internal Combustion Engines) 2008年第SUPPL.期26卷 101-106页

作者： Huang, Zuo-Hua Jiang, De-Ming Wang, Xi-Bin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

In this paper, the statues and development trends of combustion research in internal combustion engines are discussed from several aspects. Some key issues in combustion of internal combustion engines are raised. The combustion in internal combustion engines is a complex process with chemical reaction and energy conversion and there are still many aspects needed to be clarified, especially the chemical reaction mechanism and soot formation. Meanwhile, combustion diagnostic is playing an increasing role in the understanding of combustion. The motivation to deepen the research is the continuous requirement of high-efficiency and low-emission engines. Remarkable progress has been achieved in developing low-emission combustion concept like HCCI and low-temperature combustion. Alternative fuel engines become an important aspect in engine research and development. Advanced combustion technology combined with fuel control technology and after-treatment can realize the high-efficient and low-emission target.

关键词： Internal combustion engines

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Study on the characteristics of flowing organization in DMFC. Part I: Model development of cell with conventional symmetrical plates

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Taiyangneng Xuebao/Acta Energiae Solaris Sinica 2008年第9期29卷 1155-1160页

作者： Yin, Benhao He, Yaling Li, Xianglin Miao, Zheng State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

A two-dimensional, steady-state model of a direct methanol fuel cell (DMFC) with liquid methanol feed was developed. The electrode kinetics, multi-component transport and methanol crossover phenomenon were all considered. The effect of channels disposal density, the influence of backing layer, catalyst layer and polymer electrolyte membrane thickness on mass transfer and cell performance was investigated. The results showed that: with the increase of channels disposal density and the increase of catalyst layer thickness, the equality of reaction rate and cell performance will elevated. The sizes of catalyst layer and membrane effect farthest, the correspondingly optimized work can increase the average current density about 131.0% and 17.8%. There are moderate optimal thickness sizes of backing layer and membrane, and the sizes should be chosen after thinking about the sizes of flow field plate and MEA.

关键词： Methanol

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Effect of Pb2+ doping on band gap of Cd1-xZexS solid solution and photocatalytic water splitting activity

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Hsi-An Chiao Tung Ta Hsueh/Journal of Xi'an Jiaotong University 2008年第1期42卷 110-113页

作者： Xing, Chanjuan Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Pb2+ doped Cd0.2Zn0.8S and Cd0.8Zn0.2S were prepared with coprecipitation method. The results indicate that the valence band of Cd0.2Zn0.8S solid solution with wide band gap is heightened by the Pb 6s level hybridization with valence band, and the photocatalytical hydrogen evolution ability is improved. When Pb2+ is doped in Cd0.8Zn0.2S solid solution with narrow band gap, it acts as a recombination center and is unable to improve water splitting activity of the catalyst. So the doping of Pb2+ is effective only for the semiconductor with wide band gap.

关键词： Photocatalysis

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Effect of rotation on the flow and heat transfer performance of blade leading edge with impingement holes

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2008年第8期29卷 1397-1399页

作者： Zhang, Da-Hai Zeng, Min Luo, Lai-Qin Wang, Qiu-Wang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The numerical simulation technique was employed to study the flow and heat transfer performance of the rotating cooling channel with feed chamber and impingement chamber. The discharge coefficient of the impingement holes and the average Nusselt number of the impingement target surface in the blade leading edge in rotating were obtained. The result shows that the Coriolis force induced by the rotation effect can change the discharge coefficient of the impingement holes. With the increase of the rotating speed, the Coriolis force effect becomes more obvious. The discharge coefficient increases with the increase of rotating Reynolds number and outflow ratio, and decreases with the increase of the inlet Reynolds number. The influence of the rotation on the average Nusselt number of the impingement target surface is not obvious. With the increase of the rotating speed, Nusselt number increases slightly only at high rotating speed.

关键词： Rotation

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Research on holographic interference pattern of laser holographic interferometric technique

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Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument 2008年第SUPPL. 2期29卷 438-442页

作者： Guo, Ying He, Maogang Zhong, Qiu Zhang, Ying State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The processing of interference fringe is the most important step in holographic interferometric technique. The interference fringe of mass diffusion were gathered and proposed, and 3 key steps in the process which reduce the precision mostly were improved in this paper. The improvements include the following steps: wavelet de-noise, frequency-domain wave filtering, phase unwrapping. The categories of noise were analyzed and some specific methods were used to reduce the noise. The improvements increased the precision greatly, and established a solid foundation for the using of laser holographic interferometric technique.

关键词： Wavelet transforms

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