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16th World Hydrogen Energy Conference 2006, WHEC 2006

作者： Jing, Dengwei Guo, Lie-Jin Xing, Chanjuan Yan, Qiuhui State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China

ISBN: (纸本)9781622765409

Nanosize WS2 sensitized mesoporous TiO2 was prepared to extend the adsorption of the wide band gap TiO2 into visible light region. Compared with nonporous particle TiO2 substrate, it was found that the existence of mesopore is important for larger amount of WS 2 loading and inhibition of the light-induced detachment of WS 2 particles from the TiO2 substrate during photocatalytic reaction, which leads to higher photocatalytic activity and stability. We also found that the rate-determining step for photocatalytic hydrogen production is the transfer of electrons from TiO2 substrate to H+ in solution, when the recombination between electrons and holes within TiO 2 could be neglected. In this case, deposition of Pt at the surface of semiconductor is indispensable for efficient hydrogen production.

关键词： Titanium dioxide

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Multiplicity Analysis in Reactive Distillation Column Using ASPEN PLUS

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Chinese Journal of Chemical engineering 2006年第3X期14卷 301-308页

作者：杨伯伦吴江赵国胜王华军路士庆 State Key Laboratory of Multiphase Flow in Power Engineering Xi＇an Jiaotong University Xi＇an 710049 China

Reactive distillation processes for synthesis of ethylene glycol （EG） and ethyl tert-butyl ether （ETBE） were modeled with the simulation package ASPEN PLUS. The input multiplicity and output multiplicity were discussed with the method of sensitivity analysis for both cases. In EG production process, steady state multiplicities were studied in terms of effective liquid holdup volume and boil-up ratio. In ETBE synthesis process, the user kinetic subroutine was supplied into ASPEN PLUS firstly, and then the composition, temperature and reaction-rate profiles within the reactive distillation column were presented in detail. A set of stable solution branches based on distinct initial guesses for a range of boil-up ratio were found in EG synthesis. Input multiplicities were observed for a range of reboiler duty at several values of reflux ratio for ETBE synthesis process. These results can be used to avoid excessive energy consumption and achieve optimum design of reactive distillation column.

关键词： reactive distillation ASPEN PLUS multiplicity ethyl tert-butyl ether ethylene glycol

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Local flow Regime Transition Criteria of Gas-Liquid Two-phase flow in Vertical Upward Tube with a Horizontal Rod

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Chinese Journal of Chemical engineering 2006年第4X期14卷 442-449页

作者：胡志华杨燕华刘磊周芳德 School of Mechanical Engineering Shanghai Jiaotong University Shanghai 200030 China State Key Laboratory of Multiphase Flow in Power Engineering Xi＇an Jiaotong Univeristy Xi＇an 710049 China

The upward multiphase cross flow and heat transfer in the vertical tube may occur in oil production and chemical facilities. In this study, the local flow patterns of an upward gas-water two phase cross flow in a vertical tube with a horizontal rod have been investigated with an optical probe and the digital high speed video system. The local flow patterns are defined as the bubble, slug, churn and annular flow patterns. Optical probe signals are ana- lyzed in terms of probability density function, and it is proved that the local flow patterns can be recognized by this method. The transition mechanisms between the different flow patterns have been analyzed and the corresponding transitional models are proposed. Finally, local flow pattern maps of the upward gas-water two-phase flow in the vertical tube with a horizontal rod are constructed.

关键词： gas-liquid two-phase cross flow local flow pattern transition

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Analysis of flow instabilities in forced-convection steam generator

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Nuclear Science and Techniques 2006年第3期000卷 185-192页

作者： WU Ge-Ping QIU Sui-Zheng SU Guang-Hui JIA Dou-Nan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Because of the practical importance of two-phase instabilities, substantial efforts have been made to date to understand the physical phenomena governing such instabilities and to develop computational tools to model the dynamics. The purpose of this study is to present a numerical model for the analysis of flow-induced instabilities in forced-convection steam generator. The model is based on the assumption of homogeneous two-phase flow and thermodynamic equilibrium of the phases. The thermal capacity of the heater wall has been included in the analysis. The model is used to analyze the flow instabilities in the steam generator and to study the effects of system pressure, mass flux, inlet temperature and inlet/outlet restriction, gap size, the ratio of do /di, and the ratio of qi/qo on the system behavior.

关键词： Steam generator Forced convection flow instability

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An investigation of flow characteristics and critical heat flux in vertical upward round tube

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Nuclear Science and Techniques 2006年第3期000卷 170-176页

作者： FAN Pu QIU Sui-Zheng JIA Dou-Nan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Prediction of critical heat flux (CHF) in annular flow is important for the safety of once- through steam generator and the reactor core under accident conditions. The dryout in annular flow occurs at the point where the film is depleted due to entrainment, deposition, and evaporation. The film thickness, film mass flow rate along axial distribution, and CHF are calculated in vertical upward round tube on the basis of a separated flow model of annular flow. The theoretical CHF values are higher than those derived from experimental data, with error being within 30%.

关键词： Annular flow Critical heat flux Dryout Entrainment Deposition

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Theoretical investigation on the steady-state natural circulation characteristics of a new type of pressurized water reactor

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Nuclear Science and Techniques 2006年第5期000卷 314-320页

作者： GOU JunLi QIU SuiZheng SU GuangHui JIA DouNan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

This article presents a theoretical investigation on the steady-state natural circulation characteristics of a new type of pressurized water reactor. Through numerically solving the one-dimensional steady-state single-phase conservative equations for the primary circuit and the steady-state two-phase drift-flux conservative equations for the secondary side of the steam generator, the natural circulation characteristics were studied. On the basis of the preliminary calculation analysis, it was found that natural circulation mass flow rate was proportional to the exponential function of the power and that the value of the exponent is related to the operating conditions of the secondary side of the steam generator. The higher the outlet pressure of the secondary side of the steam generator, the higher the primary natural circulation mass flow rate. The larger height difference between the core center and the steam generator center is favorable for the heat removal capacity of the natural circulation.

关键词： Pressurized water reactor Natural circulation characteristics Height difference

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Study of a PEMFC performance based on a novel current distribution measurement method

Study of a PEMFC performance based on a novel current distri...

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16th World Hydrogen Energy Conference 2006, WHEC 2006

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

ISBN: (纸本)9781622765409

With the novel and simple current distribution measurement gasket developed by MPFL, the performance of a single PEM fuel cell with serpentine flow field was investigated without modifying any of its components. Inhomogeneous current distributions were demonstrated clearly by the measurement results. Current distribution at different cell operating parameters, including reactant gas flow rate, reactant gas humidification temperature and cell operating temperature, were measured and the effects of such parameters were analyzed. Reactant gas flow rate exert effects on current distribution by influencing the reactant concentration distribution, while the critical effects of gas humidification and cell temperature is caused by their significant influence on water balance and water distribution in PEM fuel cell. To fully understand the combined effects of such factors, simultaneous measurement of current distribution, reactant distribution, temperature distribution and humidification distribution is necessary and will be helpful.

关键词： flow of gases

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Two dimensional numerical simulation of tapered pulse tube refrigerator

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2006年第2期27卷 199-201页

作者： Zhao, Chun-Feng He, Ya-Ling Ding, Wen-Jing Yang, Wei-Wei Tao, Wen-Quan State Key Lab. of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Two-dimensional numerical simulation of the viscous compressible oscillating flow was carried out for the uniform cross-section and tapered pulse tubes by using a compressible SIMPLEC algorithm code developed by the authors. Effects of the taper angle on the performance of the pulse tube refrigeration were studied. The results showed that there was an optimum taper angle for tapered pulse tube refrigerator. With this optimum taper angle, the refrigerator performance can be improved a lot. But when the taper angle becomes larger than the optimum value, the cooling performance becomes inferior to that of the circular tube. The inherent mechanism of how the tapered pulse tube affects the performance of pulse tube refrigerator was also studied from the view point of second flow distribution in the pulse tube. Compared to the uniform cross-section pulse tube, the values of second flow in tapered pulse tube change a lot and the distribution of second flow becomes uneven as well. This is the main reason that the performance of tapered pulse tube can be improved compared to uniform cross-section pulse tube.

关键词：锥形脉管二次流数值研究

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Convenient model of pressure gradient calculation of gas-liquid slug flow in vertical wellbore

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Zhongguo Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of China University of Petroleum (Edition of Natural Science) 2006年第4期30卷 75-77+85页

作者： Wang, Wei-Yang Chen, Ting-Kuan Luo, Yu-Shan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China College of Petroleum Engineering China University of Petroleum Dongying 257061 China

Based on mechanistic analysis of gas-liquid slug flow in vertical wellbore, a convenient model for pressure gradient calculation was developed by equivalent unit cell approach. The method of predicting liquid holdup in liquid slug was determined according to experimental data, and correlation experimental data from literatures were used to evaluate the model. The analysis results show that this model is relative to few parameters and easy to calculate, and the test data from different sources can be predicted with fairly well precision. In addition, much difference results can be achieved by variant correlations for liquid holdup in liquid slug, but the prediction of pressure gradient is not sensitive to the liquid holdup under the experimental conditions.

关键词： Gas-liquid slug flow multiphase flow Pressure gradient Vertical wellbore

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HYDRODYNAMIC RESISTANCE EFFECT OF FLUID LAYER BETWEEN TWO IMMERSED APPROACHING PARTICLES

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China Particuology 2006年第5期4卷 220-228页

作者： Yanpeng Li Bofeng Bai School of Environmental Science and Engineering Chang'An University Xi'an 710064 P.R. China State Key Lab of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 P.R. China

A three-dimensional direct simulation of an immersed solid particle approaching another particle, or a flat wall, is conducted to investigate the mechanics of hydrodynamic impact of immersed particles. The simulation method is based on a modified immersed boundary method using a fixed grid system. When the particle separation distance becomes smaller than grid spacing, to account for the hydrodynamic resistance effect of liquid layer between particles near contact, a microlayer model is developed to allow determination of the pressure profile within the micro-layer without neglecting the inertial force of the layer flow. The pressure force is then taken into account in equation of particle motion. Comparisons of the simulation results with the experimental results reported in the literature are shown to substantiate the model presented in this study. The simulations reveal the complex three-dimensional flow field of the liquid and the motion of the approaching particle. The fluid pressure in the gap caused by the unsteady motion of the particle is significantly increased when the separation distance of particles is less than about one-tenth diameters of particle. Therefore the velocity of approaching particle starts to decrease due to the hydrodynamic resistance force at this position.

关键词： direct simulation microlayer model immersed boundary method hydrodynamic resistance effect

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