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Preparation of CdS photocatalyst and its performance of hydrogen production

Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology 2006年第SUPPL. 2期28卷 164-168页

作者： Zhang, Xiang-Hui Jing, Deng-Wei Xing, Chan-Juan Guo, Lie-Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Cadmium sulfide photocatalyst was prepared by hydrothermal methods with one-step and two-step methods, respectively. Platinum was loaded on the surface of prepared photocatalysts and its optimal loading amount was examined. All the prepared photocatalysts were characterized by XRD, UV-Vis, XRF, SEM and TEM and their pohtocatalytic activity was evaluated by H2 evolution from water under visible light. It was found that the photocatalyst prepared by two-step showed markedly improved hydrogen production activity.

关键词： CdS Hydrogen production Photocatalyst

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Investigation on heat transfer characteristics of fully developed flow in bilaterally heated narrow annuli

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Hedongli Gongcheng/Nuclear power engineering 2006年第SUPPL. 1期27卷 57-60页

作者： Zeng, He-Yi Qiu, Sui-Zheng Jia, Dou-Nan School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Numerical research was carried out on the convection heat transfer characteristics in bilaterally heated annular channel with narrow gap under the conditions of fully developed flow, where the inner and outer walls are heated by uniform but unequal heat fluxes. Calculation results show that the ratio of the inner wall heat flux to the outer wall heat flux has great effects on the heat transfer characteristics in bilaterally heated narrow annuli. With the increase of the inner wall heated flux, the heat transfer coefficient at the outer wall of the inner tube will decrease, while the heat transfer coefficient at the inner wall of outer tube will increase. These numerical results are in good agreement with some experimental results in open literatures. Numerical results also show that the decrease of the annuli gap will yield heat transfer deterioration during flowing in narrow annular channels.

关键词： Heat transfer

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Stability of stratified flow and slugging in horizontal gas-liquid flow

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Progress in Natural Science:Materials International 2005年第11期15卷 1026-1034页

作者： GU Hanyang and GUO Liejin (State key laboratory of multiphase flow in power engineering, Xi’an Jiaotong University, Xi’an 710049, China) State Key Laboratory of Multiphase Flow in Power Engineering Xi''an Jiaotong University Xi''an 710049 China

A transient one-dimensional two-fluid model is proposed to investigate numerically the interfacial instability and the onset of slugging for liquid-gas flow in a horizontal duct. In the present model, the effects of surface tension and transverse variations in dynamic pressure are taken into account. The evolution of interfacial disturbances is displayed and compared with the linear viscous Kelvin-Helmholtz stability analyses. It shows that interfacial wave is more instable due to the non-linear effect. The model predicts well the stability limit of stratified flow in comparison with the experimental data, and also automatically tracks the onset of slugging. The results show that the initiation of hydrodynamic slugging is related to local interfacial instability. Based on the cycle of slugging, a model for slug frequency is presented, which predicts the trends of slug frequencies with gas/liquid flow rate well in comparison with the available data. The effects of physical properties on slugging have been examined. It is found that with the increase in the gas viscosity and liquid density the slugging would be inhibited, whereas, with the increase in liquid viscosity and gas density, the slugging can be promoted.

关键词： two-fluid model Kelvin-Helmholtz stability interfacial instability onset of slugging gas-liquid stratified flow.

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Thermal boundary condition for the thermal lattice Boltzmann equation

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Physical Review E 2005年第1期72卷 016703-016703页

作者： G. H. Tang W. Q. Tao Y. L. He State Key Laboratory of Multiphase Flow School of Energy and Power Engineering Xi’an Jiaotong University Xi’an Shaanxi 710049 China

A thermal boundary condition for a double-population thermal lattice Boltzmann equation (TLBE) is introduced and numerically demonstrated. The unknown distribution population at the boundary node is decomposed into its equilibrium part and nonequilibrium parts, and then the nonequilibrium part is approximated with a first-order extrapolation of the nonequilibrium part of the populations at the neighboring fluid nodes. Numerical tests with Dirichlet and Neumann boundary constraints show that the numerical results of the TLBE together with the present boundary schemes agree well with the analytical solutions and those of the finite-volume method.

关键词： NAVIER-STOKES EQUATION BGK MODEL HEAT-TRANSFER GAS AUTOMATA flowS SIMULATION PRESSURE VELOCITY

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Gas slippage effect on microscale porous flow using the lattice Boltzmann method

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Physical Review E 2005年第5期72卷 056301-056301页

作者： G. H. Tang W. Q. Tao Y. L. He State Key Laboratory of Multiphase Flow School of Energy and Power Engineering Xi’an Jiaotong University Xi’an Shaanxi 710049 China

A lattice Boltzmann method is developed for gaseous slip flow at the pore scale in microscale porous geometries. flow characteristics through various porous structures are studied for different Knudsen numbers and inlet to outlet pressure ratios. It is found that the gas permeability is larger than the absolute permeability of porous media due to the gas slippage effect. Furthermore, the rarefaction influence on the gas permeability is more evident for porous structures with low porosity. The Klinkenberg equation is confirmed for the simulated porous structures. However, the second-order term of the Knudsen number (Kn2) cannot be neglected for gaseous flow with relatively high Knudsen numbers. A model for predicting the pressure drop of the flow through microscale porous media is presented based on the Ergun equation and the Carman-Kozeny equation by taking into account the effects of gas rarefaction and compressibility.

关键词： MEDIA PERMEABILITY SIMULATION FLUIDS MODEL MICROCHANNELS EQUATION

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Investigation on heat transfer characteristics of spiral wall with internal rib in supercritical sliding-pressure operation once-through boiler

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical engineering 2005年第16期25卷 90-95页

作者： Tang, Ren-Hu Yin, Fei Chen, Ting-Kuan National Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Within the range of pressures from 9 to 28 MPa, mass velocities from 600 to 1200 kg/(m2s), and heat fluxes from 200 to 500 kW/m2, experiments have been performed to investigate the heat transfer to water in the inclined upward internally ribbed tube with the inclined angle of 19.5 degree, the maximum outer diameter of 38.1 mm, and the thickness of 7.5 mm. Based on the experiments, it was found that heat transfer enhancement of the internally ribbed tube could postpone departure from nucleate boiling at the sub-critical pressure. However, the heat transfer enhancement decreased near the critical pressure. At supercritical pressure, the temperature difference between the wall and fluid increased near the pseudo-critical temperature, but the increasing of wall temperature was less than that of departure from nucleate boiling at sub-critical pressure. When pressure was close to the critical pressure, the temperature difference between the wall and fluid greatly increased near the pseudo-critical temperature. Heat transfer to supercritical water in the inclined upward internally ribbed tube was enhanced or deteriorated near the pseudo-critical temperature with the variety of ratio between the mass velocity and the heat flux. Due to the rotational flow of the internal groove reducing the effect of nature convection, the internal wall temperature of the inclined upward internally ribbed tube uniformly distributed along the circumference. The maximum internal wall temperature difference of the inclined upward internally ribbed tube along the circumference was only 10 degree Centigrade when the fluid enthalpy exceeds 2000 kJ/kg. Considering the effect of acute variety of the fluid property on heat transfer, the correlation of heat transfer coefficient on the top of the inclined upward internally ribbed tube have been provided.

关键词： Boilers

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Experimental study of the hydrogen production from coal/CMC gasified in super critical water by continuous flow thermal-catalytic reaction system

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Taiyangneng Xuebao/Acta Energiae Solaris Sinica 2005年第6期26卷 874-877页

作者： Yan, Qiuhui Guo, Liejin Liang, Xing Zhang, Ximin Hao, Xiaohong Ma, Lijing State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

As coal was transported homogeneously at high pressure by adding the sodium carboxymethylcellulose (CMC), the hydrogen production from catalytic gasification of coal/CMC in supercritical water (SCW) was investigated. The experimental results showed that the molar fraction of hydrogen is higher than that in conventional gasification. H2, CO2 and CH4 are the main product gases, the higher pressure and higher CMC content is advantage of hydrogen production. Longer residence time is favorite to gasification of coal/CMC, but it is not advantage of hydrogen production from coal/CMC gasified in SCW at 20-25 MPa, 15-30 s and 650°C.

关键词： Hydrogen

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Probabilistic distribution of initial ejection state of particles in equilibrium sand transport

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2005年第4期26卷 613-616页

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

The equilibrium sand transport is simulated by Lagrange model combined with the probabilistic distributions of initial speed and angle of ejection sand grain in this paper. Five forms of the possible distributions are summarized from the previous study results published in literature. Since the macro-quantities simulated by rational distribution should be coincident well with experimental result, the rationality of the distributions can be tested by comparing the quantities simulated from these distributions with the experimental quantities. Detailed analysis indicates that the distribution of initial speed and angle of ejected grains in equilibrium sand transport should be a monotonous decline function. According to the experimental data a segmented function comprised by an exponential distribution and a normal distribution is suggested in this paper. This distributions is confirmed by further comparison with experimental data.

关键词： Distribution Ejection Equilibrium transport Sand

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Study on dryout point in vertical narrow annuli

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Nuclear Science and Techniques/Hewuli 2005年第1期000卷

作者： TIAN Wen-xi AYE Myint QIU Sui-zheng JIA Dou-nan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an710049

Prediction of dryout point is experimentally investigated with deionized water upflowing through narrow annular channel with 1.0 mm and 1.5 mm gap respectively. The annulus with narrow gap is bilaterally heated by AC current power supply. The experimental conditions covered a range of pressure from 0.8 to 3.5 MPa, mass flux of 26.6 to 68.8 kg·m-2·s-1 and wall heat flux of 5 to 50 kW·m-2. The location of dryout is obtained by observing a sudden rise in surface temperature. Kutateladze correlation is cited and modified to predict the location of dryout and proved to be not a proper one. Considering in detail the effects of geometry of annuli, pressure, mass flux and heat flux on dryout, an empirical correction is finally developed to predict dryout point in narrow annular gap under low flow condition, which has a good agreement with experimental data.

关键词： Narrow annular channel Bilaterally heating Dryout point Critical quality Annular flow

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Economic performance analysis and heat exchange calculating in the system of storage ice by spraying water in winter

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Yingyong Jichu yu Gongcheng Kexue Xuebao/Journal of Basic Science and engineering 2005年第SUPPL.期13卷 177-183页

作者： Liu, Weimin Bi, Qincheng Guo, Yajun Dong, Mingxiao Zhang, Linhua Gao, Feng State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China School of Environmental and Municipal Eng. Xi'an University of Architecture and Technology Xi'an 710049 China Shandong Institute of Architecture and Engineering Jinan 250014 China

The system of ice-making by spraying water in winter and utilizing the ice in summer is pollution-free and economizes the first investment, operating cost, and reduces the peak of electric power in summer. Through establishing the energy equilibrium equation of sprayed water drop, the relation between the diameter of water droplet and the time of icing at different ambient temperature and coefficient of performance of the system of ice-making by spraying water has been obtained. The errors between the numerical solution and the experimental data lie in a range of 7% to 10%, indicating that the model is reasonable. The method of the ice making is promising in the exercisable region to substitute the mechanical refrigeration system.

关键词： Cold storage

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