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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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PIV measurement of turbulent mixing layer

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2008年第11期29卷 1867-1871页

作者： Guo, Fu-De Chen, Bin Wang, Zhi-Wei Guo, Lie-Jin Zhang, Xi-Min State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

In present paper a turbulent mixing layer with the velocity ratio 4:1 which was produced by a special designed splitter plated placed in a vertical rectangular channel was experimentally investigated by PIV. The Reynolds number based on the velocity difference of two steams and hydraulic diameter of the channel ranges from 4400-158400. It is found that the scale of coherent vortex structure increases with increasing the Reynolds number and then decreases with continuously increasing the Reynolds number. The injected bubble will delay or hinder the evolution of the coherent structures. Afterwards the statistical and instantaneous distributions of Reynolds stress, turbulent intensity, vorticity and swirling strength are obtained. The results show that all these turbulent parameters exist only in a very narrow conical region in the downstream of the mixing layer. The Reynolds stress and turbulent intensity first increase and then decrease with increasing the Reynolds number and decrease with the evolution of mixing layer, while vorticity and swirling strength increase with increasing the Reynolds number and decrease with the evolution of mixing layer.

关键词： Reynolds number

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Influence of the initial condition on pool water instantaneous flash evaporation

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2008年第8期29卷 1335-1338页

作者： Guo, Ying-Li Deng, Wei Yan, Jun-Jie Wang, Gui-Fang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

An experimental study has been performed to investigate pool water instantaneous flash evaporation in a rectangle chamber. The water level was at 40 mm, 60 mm, 100 mm, 150 mm. Initial conditions of the liquid varied from 55 to 88C temperature and 3 to 35C superheat. Visualization of the phenomenon using a CCD camera lets us firstly point out the influence of the initial conditions on the flashing phenomenon. The experimental results show that at a constant initial water temperature, the greater the superheat approaches, the more quickly the liquid temperature will decrease. At a constant superheat, the initial water temperature has little influence on the decrease rate of the water temperature. The higher the water level will be, the slower the water temperature will decrease as well as the higher the water temperature will be when the flashing is finished. Experimental study allows us to correlate the water temperature with the initial water temperature and the superheat while flashing is going.

关键词： Water temperature

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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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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

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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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