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作者： Yu, Bo Wei, Jinjia Kawaguchi, Yasuo Department of Oil and Gas Storage and Transportation Engineering China University of Petroleum Beijing 102249 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Department of Mechanical Engineering Faculty of Science and Technology Tokyo University of Science Noda Chiba 278-8510 Japan

In Part I [Wei et al., 2004, 2004 ASME Int. Mech. Eng. Conference], we presented the experimental results for swirling flows of water and cetyltrimethyl ammonium chloride (CTAC) surfactant solution in a cylindrical vessel with a rotating disk located at the bottom for a Reynolds number of around 4.3 × 104 based on the viscosity of solvent. For the large Reynolds number, violent irregular instantaneous secondary flows at the meridional plane were observed by use of a particle image velocimetry system. Because of the limitations of our computer resources, we did not carry out direct numerical simulation for such a large Reynolds number. The LES and turbulence model are alternative methods, but a viscoelastic LES/turbulence model has not yet been developed for the surfactant solution. In this study, therefore, we limited our simulations to a laminar flow. The marker-and-cell method proposed for Newtonian flow was extended to the viscoelastic flow to track the free surface, and the effects of Weissenberg number and Froude number on the flow pattern and surface shape were studied. Although the Reynolds number is much smaller than that of the experiment, the major experimental observations, such as the inhibition of primary and secondary flows and the decrease of the dip of the free surface by the elasticity of the solution, were qualitatively reproduced in the numerical simulations. Copyright © 2006 by ASME.

关键词： Fluids

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Swirling flow of a viscoelastic fluid with free surface - Part I: Experimental analysis of vortex motion by PIV

Swirling flow of a viscoelastic fluid with free surface - Pa...

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作者： Wei, Jinjia Li, Fengchen Yu, Bo Kawaguchi, Yasuo State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China University of Tokyo Meguro-ku Tokyo 153-5805 Japan Oil and Gas Storage and Transportation Engineering China University of Petroleum Beijing 102249 China Department of Mechanical Engineering Faculty of Science and Technology Tokyo University of Science Noda 278-8510 Japan

The swirling flows of water and CTAC (cetyltrimethyl ammonium chloride) surfactant solutions (50-1000 ppm) in an open cylindrical container with a rotating disc at the bottom were experimentally investigated by use of a double-pulsed PIV (particle image velocimetry) system. The flow pattern in the meridional plane for water at the present high Reynolds number of 4.3 × 104 differed greatly from that at low Reynolds numbers, and an inertia-driven vortex was pushed to the comer between the free surface and the cylindrical wall by a counter-rotating vortex caused by vortex breakdown. For the 1000 ppm surfactant solution flow, the inertia-driven vortex located at the corner between the bottom and the cylindrical wall whereas an elasticity-driven reverse vortex governed the majority of the flow field. The rotation of the fluid caused a deformation of the free surface with a dip at the center. The dip was largest for the water case and decreased with increasing surfactant concentration. The value of the dip was related to determining the solution viscoelasticity for the onset of drag reduction. Copyright © 2006 by ASME.

关键词： Fluids

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Liquid kinematic viscosity of the binary mixtures of methanol and castor oil

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2006年第SUPPL. 1期27卷 79-81页

作者： Meng, Xian-Yang Wu, Jiang-Tao Liu, Zhi-Gang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The liquid kinematic viscosity of the binary mixtures of methanol and castor oil are reported over the temperature range from 243~353 K made with a calibrated Ubbelohde-type capillary viscometer. The total experimental uncertainty is less than 1.06%. In addition, the results were correlated as a function of temperature as the kinematic viscosity equation of the binary mixtures. The absolute average deviation and the maximum deviation of the experimental results from the correlated equation are 1.11% and 3.31%, respectively.

关键词： Castor oil Kinematic viscosity Liquid mixtures Methanol

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New method of preparing solid solution ZnS-CuInS2 and its activity of photocatalytic splitting water for hydrogen production

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Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology 2006年第SUPPL. 2期28卷 240-244页

作者： Guo, Peng-Hui Guo, Lie-Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Synthesis of solid solution ZnS-CuInS2 has been demonstrated. The crystallinity and stability of catalysts were highly improved by the combination of two usual ways used for improving the crystallinity of materials-calcination at high temperature or hydrothermal, so was the activity of photocatalytic splitting water for hydrogen production. The catalysts were characterized by XRD, BET, SEM, XRF and UV-Vis. The results of the photocatalytic hydrogen production showed that the catalyst had the highest stability and activity by H2S inflowing to the metal cation solution following with calcination and hydrothermal. After the catalyst was loaded with 3% Pt, the velocity of hydrogen production has been further improved to 127 μmol/h. And its apparent quantum efficiency at 420 nm was up to 4.43%.

关键词： Photocatalytic hydrogen production Preparation ZnS-CuInS2 solid solution

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Shape of isolated bubble in intermittent flows in horizontal straight tube

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2006年第3期27卷 433-436页

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

An experimental study of the shape of a single bubble similar to those observed in horizontal plug/slug flow was performed by visual observation and conductance probes in this paper. The results show that the shape of the nose and body of bubble depends on the Froude number defined by gas/liquid mixture velocity, whereas the shape of the back region of bubble depends on both the Froude number and bubble length. The photographic pictures show that the motion of bubble is related to the characteristics of bubble head and the transition from plug flow to slug flow occurs when the back of the bubble changes from staircase to hydraulic jump pattern with increasing the Froude number and bubble length.

关键词： Bubble shape flow pattern transition Plug flow Slug flow

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Numerical study of heat transfer and fluid flow in a periodically wavy channel

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Jisuan Wuli/Chinese Journal of Computational Physics 2006年第1期23卷 93-97页

作者： Xie, Gong-Nan Wang, Qiu-Wang Luo, Lai-Qin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The periodically fully developed laminar heat transfer and fluid flow in a two-dimensional wavy channel in a compact heat exchanger are investigated numerically. Calculations are performed at Pr = 0.7, in the range of Re = 100-1100 with non-orthogonal non-staggered grids. The Semi-Implicit Method for Pressure Linked Equations Revised (SIMPLER) algorithm in the curvilinear body-fitted coordinates is used. The effect of the wavy height and distance on momentum and heat transfer is studied. Performance of model parameters is evaluated. It is shown that the overall Nusselt numbers and friction factors increase with the increase of Reynolds numbers. The friction factors and overall Nusselt numbers increase as increasing the wavy height or decreasing the wavy distance. The overall Nusselt numbers increase significantly with the wavy height, especially at high Reynolds numbers. The best wavy height and distance are 1.15 mm and 13 mm, respectively.

关键词： Channel flow

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Structural and photoelectrochemical characterization of CdS thin film electrodes in photoelectrochemical water splitting system

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Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology 2006年第SUPPL. 2期28卷 568-573页

作者： Su, Jin-Zhan Li, Ming-Tao Zhang, Xi-Min Guo, Lie-Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The structural properties of CdS thin films obtained by ultrasonic spray pyrolysis at different substrate temperature were studied by X-ray diffraction (XRD), scan electron microscope (SEM), Raman spectrum and Uv-vis absorption spectrum. The experimental results show that the crystallinity level gets higher with increasing substrate temperature while the bandgap remains constant. This deposition method should be an effective method as the deposited film looks uniform and smooth in the SEM image. Furthermore, the photoelectrochemical activities of CdS thin films used as electrode to split water to hydrogen and oxygen were investigated. The photoelectrochemical activity increases and then decreases with increasing substrate temperature which forms a peak value at 300 °C . Under a light intensity of 187 mW/cm, the electrode deposited at 300 °C gives a saturated photocurrent of 4.1 mA/cm with increasing electrode potential. The highest energy conversion efficiency was calculated as 0.68% at electrode potential of -0.13 V (vs SCE).

关键词： CdS Hydrogen solar Photoelectrochemistry Ultrasonic spray pyrolysis (USP)

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Research on optimization of the parameters for continuous anaerobic hydrogen production

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Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology 2006年第SUPPL. 2期28卷 174-180页

作者： Wu, Xiao-Min Yang, Hong-Hui Guo, Lie-Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Orthogonal array tests were carried out to investigate the optimal temperature(T), hydraulic retention time (HRT), pH and C/N ratio of anaerobic fermentative hydrogen production using a 20 L continuous stirred-tank reactor (CSTR). The results showed that hydrogen production rate, hydrogen content, glucose utilization ratio and hydrogen yield reached the maximum of 6.00 L/h, 55.0%, 99.0%, 157.86 mL/g in appropriate conditions, respectively. The optimal pH, T, HRT and C/N ratio were 5.0, 33.5-36.5 °C, 8.34 h, 112/1.55, respectively. A confirmation experiment was carried out to verify the optimal parameters obtained by orthogonal array tests. Hydrogen production rate, hydrogen content, glucose utilization ratio and potential hydrogen yield reached the maximum of 5.66 L/h, 54.0%, 0.97, 191.18 mL/g, respectively. The results of the confirmation experiment showed that hydrogen production with the optimal parameters was more efficient than that in the orthogonal array tests, and that suggested the orthogonal array tests were successful.

关键词： Anaerobic fermentation CSTR Hydrogen production Orthogonal array test

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Effects of reactant gas flow rates on the current distribution in a PEM fuel cell

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Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology 2006年第SUPPL. 2期28卷 601-604页

作者： Shang, De-Hua Zhang, Guang-Sheng Guo, Lie-Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

As an important performance diagnosis tool, in-situ measurement of current distribution in PEM fuel cells is helpful for better understanding of internal transport phenomena and optimization of fuel cell structures and operating parameters. With a specially developed current distribution measurement gasket, the effects of reactant gas flow rates on the current distribution in a PEM fuel cell with single serpentine flowfield were investigated. Experimental results show that insufficient hydrogen or air leads to decreased current density along the gas flow direction. Higher reactant gas flow rate favors not only the local performance but also the homogeneity of current distribution. But current distribution almost ceases to change with further increase of hydrogen flow rate when it reaches certain value.

关键词： Current distribution Fuel cell Proton exchange membrane (PEM)

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Experimental study of liquid slug velocity in horizontal pipe line

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2006年第1期27卷 71-74页

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

The velocities of liquid slugs in continuous slug flow were studied experimentally in a 133 m long horizontal pipeline. Measurements were performed by cross-correlating the signals of two pairs of probes installed along the pipeline. Correlations of liquid slug velocities with the mixed velocities are presented. It is found that the correlations depend on Froude numbers. At low Froude numbers, the correlation from the measurements of the upstream probes is consistent with that from the measurements of the downstream probes and both correlations agree well with the results of other researchers. But there is difference between the correlation of the upstream probes and that of the downstream probes at high Froude numbers. Compared with the experimental data of other researchers, it is expected that the velocities of liquid slugs are affected by the void fraction in liquid slugs and the evolution of the lengths of liquid slugs and elongated bubbles along pipeline. However, the wake effect may have no influence on the liquid slug velocities.

关键词： Liquid slug velocity Slug flow Slug length Two-phase flow

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