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An Adaptive VOF Method on Unstructured Grid

AIP Conference Proceedings 2011年第1期1376卷 642-644页

作者： L. L. Wu M. Huang B. Chen State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

In order to improve the accuracy of interface capturing and keeping the computational efficiency, an adaptive VOF method on unstructured grid is proposed in this paper. The volume fraction in each cell is regarded as the criterion to locally refine the interface cell. With the movement of interface, new interface cells (0 ≤ f ≤ 1) are subdivided into child cells, while those child cells that no longer contain interface will be merged back into the original parent cell. In order to avoid the complicated redistribution of volume fraction during the subdivision and amalgamation procedure, a predictor‐corrector algorithm is proposed to implement the subdivision and amalgamation procedures only in empty or full cell ( f = 0 or 1). Thus volume fraction in the new cell can take the value from the original cell directly, and the interpolation of the interface is avoided. The advantage of this method is that the re‐generation of the whole grid system is not necessary, so its implementation is very efficient. Moreover, an advection flow test of a hollow square was performed, and the relative shape error of the result obtained by adaptive mesh is smaller than those by non‐refined grid, which verifies the validation of our method.

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Study on the Radiation Distribution in A Fluidized Tubular Reactor for Heterogeneous Photocatalytic Hydrogen Production

Study on the Radiation Distribution in A Fluidized Tubular R...

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2011 International Conference of Environmental Science and engineering（ICESE 2011）

作者： Zhao Liang Fan Liangliang Jing Dengwei Liu Wenxu Cao Fei Zhu Xule Yang Junyin Zhang Hailong State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

Radiation distribution study is of importance for the design and the optimization of fluidized photocatalytic tubular reactor which has been developed for photocatalytic hydrogen production under direct solar light. In the present study, the radiation distribution in such reactor was successfully simulated by adopting Monte Carlo method and the six-flux radiation absorption-scattering models. Both the incident angles of light around the reactor and the concentration distribution of photocatalyst were taken into account. Our analysis indicates that the angles and the intensity of the incident rays significantly affect the radiation distribution. Moreover, it was also found that the equilibrium radiation distribution has a close relationship with the density distribution of the photocatalysts. The simulated results are expected to be helpful for obtaining the optimal operating parameters for solar photocatalytic hydrogen production.

关键词： Radiation distribution,Fluidized tubular reactor,Nanometer catalyst Compound parabolic concentrators

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Photocatalytic reforming of formic acid with simultaneous hydrogen production under visible light over CdS sensitized Na 2 Ti 2 O 4 (OH) 2

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MRS Online Proceedings Library 2011年第1期1326卷 1-6页

作者： Wendong Tang Dengwei Jing Liejin Guo State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an P. R. China

The present work reports the renewable hydrogen production by an anaerobic photocatalytic reforming of formic acid over CdS sensitized Na2Ti2O4(OH)2 nanotubes. the Na2Ti2O4(OH)2 nanotube was prepared and charactered by X-ray diffraction, UV-visible absorption, transmission electron microscopy, etc. The activity of the catalyst in formic acid was investigated. The greatest photocatalytic reforming activity of formic acid occurs as the formic acid initial concentration is 20 v.%. A probable mechanism for the photocatalytic reforming process was proposed and discussed.

关键词： nanostructure photochemical hydrothermal

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Eosin Y-sensitized ZnO/TiO 2 for efficient visible light photocatalytic hydrogen evolution

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MRS Online Proceedings Library 2011年第1期1326卷 1-6页

作者： Haipei Liu Dengwei Jing Liejin Guo State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an P. R. China

In this work a series of Eosin Y-ZnO(x%)/TiO2 were prepared. ZnO well dispersed on the surface of TiO2, which improves the adsorption of Eosin Y and the excited electron to transfer to the conduction band of TiO2. Therefore the visible light activity of 0.2%Pt-Eosin Y-ZnO(x%)/TiO2 is much higher than that of the 0.2%Pt-Eosin Y-TiO2 and 0.2%Pt-Eosin Y-ZnO. The 0.2%Pt-Eosin Y- ZnO(1.5%)/TiO2 has the highest visible light activity among the catalysts coupled with various ZnO amount, whose activity is increased by a factor of 3.5 compared to that of 0.2%Pt-Eosin Y-TiO2. It is proposed that, 0.2%Pt-Eosin Y-ZnO(1.5%)/TiO2 has the optimal trapping sites of carriers and thickness of the space-charge layer on the TiO2 particle surface, so these factors result a more efficient charge separation, an increased lifetime of the charge carriers, and the enhanced of hydrogen production.

关键词： catalytic hydrogenation energy generation

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Improved Photocatalytic H 2 Evolution from Inorganic/Organic Sacrificial Solution over Ni-Doped (CuIn) 0.2 Zn 1.6 S 2 Photocatalysts

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MRS Online Proceedings Library 2011年第1期1326卷 1-6页

作者： Xianghui Zhang Dengwei Jing Liejin Guo State Key Lab of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an PR China

The Ni-doped (CuIn)0.2Zn1.6S2 photocatalysts were prepared via a two-step ultrasonic-hydrothermal method under an environmental-friendly condition. XRD pattern profiles suggested that Ni2+ successfully doped into (CuIn)0.2Zn1.6S2 lattice. UV-Vis spectra indicated that the optical properties of the photocatalysts greatly depended on the amount of Ni doped. SEM images show that the samples were microspheres. The microsphere structures were gradually damaged with the increment of Ni doping amount. The photoactivity of (CuIn)0.2Zn1.6S2 was enhanced when Ni2+ was doped into the crystal structure. The H2 evolution performance over the prepared samples from inorganic/organic sacrificial solution was systematic investigated.

关键词： catalytic energy generation hydrogenation

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Experimental investigation of heat transfer for supercritical pressure water flowing in vertical annular channels

Experimental investigation of heat transfer for supercritica...

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作者： Gang, Wu Bi, Qincheng Yang, Zhendong Wang, Han Zhu, Xiaojing Hao, Hou Leung, L.K.H. State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an 710049 China Atomic Energy of Canada Limited Chalk River ON K0J 1J0 Canada

An experiment has recently been completed at Xi'an Jiaotong University (XJTU) to obtain wall-temperature measurements at supercritical pressures with upward flow of water inside vertical annuli. Two annular test sections were constructed with annular gaps of 4 and 6 mm, respectively, and an internal heater of 8 mm outer diameter. Experimental-parameter ranges covered pressures of 23-28 MPa, mass fluxes of 350-1000 kg/m2/s, heat fluxes of 200-1000 kW/m2, and bulk inlet temperatures up to 400 °C. Depending on the flow conditions and heat fluxes, two distinctive heat transfer regimes, referring to as the normal heat transfer and deteriorated heat transfer, have been observed. At similar flow conditions, the heat transfer coefficients for the 6 mm gap annular channel are larger than those for the 4 mm gap annular channel. A strong effect of spiral spacer on heat transfer has been observed with a drastic reduction in wall temperature at locations downstream of the device in the annuli. Two tube-data-based correlations have been assessed against the experimental heat transfer results. The Jackson correlation agrees with the experimental trends and overpredicts slightly the heat transfer coefficients. The Dittus-Boelter correlation is applicable only for the normal heat transfer region but not for the deteriorated heat transfer region. © 2011 Published by Elsevier B.V.

关键词： Heat transfer coefficients

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Deposition of Cement Kiln Ash on the Tubes of Waste Heat Recovery Boiler

Deposition of Cement Kiln Ash on the Tubes of Waste Heat Rec...

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IEEE PES Asia-Pacific power and Energy engineering Conference (APPEEC)

作者： Yufeng Wang Chunyun Hu Shi'en Hui Qinxin Zhao Qulan Zhou State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi China

Deposition of cement kiln ash on the tubes of heat recovery boiler affects the heat exchange efficiency. The basic characteristic of cement kiln ash and the deposition on the tubes with different arrangements are presented. Numerical simulation and experiment measurement show that flow field feature, especially the low-velocity zone and vortex street, causes different shape of ash deposit around the tube. The effect of ash concentration, tube arrangement and gas velocity on the deposition is analyzed. The effect of the tube diameter and the gas composition is also discussed.

关键词： Ash Electron tubes Surface treatment Heat recovery Waste heat Shape Boilers

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Decalin dehydrogenation on active carbon supported Pt-Ni bimetallic catalysts

Decalin dehydrogenation on active carbon supported Pt-Ni bim...

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International Conference on Mechanic Automation and Control engineering (MACE)

作者： Lei LingHu Weitao Wu Suitao Qi Chunhai Yi Gangli Zhu Bolun Yang Department of Chemical Engineering State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

Pt-Ni bimetallic catalysts and their corresponding monometallic catalysts supported on active carbon were prepared by incipient wetness impregnation or chelating formaldehyde reduction. The effect of feed/catalyst ratio and the metal impregnation sequence for active carbon supported bimetallic nanoparticle on dehydrogenation activity of decalin was investigated. The results showed that the conversion of decalin increased up to 72% over 3%Pt/C catalyst when the feed/catalyst ratio reached 3.3 mL/g, under which condition the catalyst was in the liquid film state, having a higher temperature and larger contact area. The Pt-Ni/C bimetallic catalyst showed higher activity than either Pt/C or Ni/C monometallic catalyst. The impregnation sequence has a significant effect on the catalytic performance of three bimetallic supported catalysts. Pt first catalyst displayed the best dehydrogenation activity and selectivity to naphthalene. It reveals that the impregnation sequence more likely altered the location of active metal species and the formation of Pt-Ni bimetallic bond, which lead to the different catalytic behavior for decalin dehydrogenation.

关键词： Nickel Hydrogen Carbon Hydrogen storage Organic chemicals X-ray scattering Chemicals

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Analysis Of Thermal-Hydraulic Performance During Full Pressure Startup Scheme Of IPWR

Analysis Of Thermal-Hydraulic Performance During Full Pressu...

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The Fifth China-Korea Workshop on Nuclear Reactor Thermal Hydraulics

作者： Liang zhao Guanghui Su Suizheng Qiu Wenxi Tian Zhangli Wang Department of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

In an integral pressurized water reactor(IPWR), the primary coolant system components and the loop system equipment are housed in the reactor pressure vessel, and the pipe lines connecting between those components are eliminated because of the requirement of compact layout in-vessel. The compactness and inherent safety of the system are enhanced with the concise structure. Thus, this design scheme is suitable for the medium or small size nuclear power plants or ships nuclear systems in the economic and technological aspects. According to the thermal- hydraulic characteristics of the IPWR,a reasonable description of the system mathematical and physical model is established, including core model, simplified pump model, once-through steam generator (OTSG) model, flow friction and heat transfer models. Meanwhile, all possible flow and heat transfer conditions are considered and the corresponding optional models are presented. In addition, the Gear method is used for the numerical solution of transient equations. The full pressure startup method is simulated with this model. Because of the adoption of modular programming techniques, both of the steady and transient state analysis codes can be applied easily to other thermal-hydraulic analysis of special reactors and special cases by modifying and updating the corresponding function modules.

关键词： Analysis Of Thermal-Hydraulic Performance During Full Pressure Startup Scheme Of IPWR

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Development of RETAC for AP1000 Thermal-hydraulic Characteristics and Safety Analysis on PRHRS Inadvertent Operation Accident

Development of RETAC for AP1000 Thermal-hydraulic Characteri...

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The Fifth China-Korea Workshop on Nuclear Reactor Thermal Hydraulics

作者： W.W.Wang G.H.Su W.X.Tian S.Z.Qiu State Key laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and Technology Xi'an Jiaotong University

In the present study, a thermal-hydraulic safety analysis code for AP1000 named RETAC (REactor Transient Analysis Code) has been developed using FORTRAN 90 language. A point reactor neutron kinetics model with six groups of delayed neutrons was adopted to describe the core thermal power transient. A distribute parameter model with two-phase drift flux model was used in the U-tube steam generator simulation. In the pressurizer simulation, a multi-region non-equilibrium model was adopted. Similar to current large commercial codes such as RELAP5 and RETRAN series, the four-quadrant analogy curves were used for the solution of the transient behaviors of the main coolant pumps. In this paper, a new and reasonable model for the passive residual heat removal heat exchanger (PRHR HX) was proposed based on basic equations of mass, momentum and energy. Gear method and Adams predictor-corrector method were adopted alternately for a better solution to ill-condition differential equations corresponding to detail processes. The PRHR HX inadvertent operation accident was chosen in the transient accident analysis. Furthermore, the simulation results obtained by RETAC were compared with that by Westinghouse-developed LOFTRAN code. The comparison results showed a good agreement and thus proved the accuracy and reliability of the RETAC code. With the adoption of modular programming techniques, the RETAC code can be easily modified and applied to higher power passive safety reactors in the future.

关键词： RELAP Development of RETAC for AP1000 Thermal-hydraulic Characteristics and Safety Analysis on PRHRS Inadvertent Operation Accident

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