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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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Electrochemical treatment of pentachlorophenol on Ni-Sb-SnO2/Ti electrodes

Electrochemical treatment of pentachlorophenol on Ni-Sb-SnO2...

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International Symposium on Water Resource and Environmental Protection (ISWREP)

作者： Yun-Hai Wang Zhou Zhe Chen Qing-Yun Zhao Jing-Lian State Key Laboratory of Multiphase Flow Department of Environmental Science and Engineering Xi'an Jiaotong University China State Key Laboratory of Multiphase Flow Department of Environmental Science and Engineering Xi'an Jiaotong University Xi'an China

Nickel and antimony doped tin dioxide (NATO) coated titanium electrodes are prepared and tested for electrochemical treatment of pentachlorophenol (PCP). The effect of nickel content on the electrochemical activity is studied using PCP as target organic waste. The nickel content has an optimized value for the activity. The NATO is characterized and the relationship between activity and oxygen to tin atomic ratio is discussed.

关键词： Nickel Tin Degradation Surface treatment ISO standards

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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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Enhancing Photocurrent in Unannealed NiS x /CdS Photoelectrochemical System for Water Splitting and Hydrogen Production

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

作者： Ning Zhang Liejin Guo State Key Laboratory of Multiphase Flow in Power Engineering (MPFL) School of Energy and Power Engineering Xi’an Jiaotong University Shaanxi PR China

In this work, NiSx was deposited on FTO by chemical bath and worked as the inner layer in order to enhance the photocurrent of CdS film. It is found the unannealed CdS/NiSx had a higher photocurrent than unannealed CdS, but after annealing, the photocurrent of CdS/NiSx showed dramatical decrease. The mechanism was discussed in detail by UPS and current-potential curves.

关键词： Ni S thin film

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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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Performance enhancement for nanofluid-cooled microchannel heat sink

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Yingyong Jichu yu Gongcheng Kexue Xuebao/Journal of Basic Science and engineering 2012年第SUPPL.期20卷 169-180页

作者： Lin, Lin Wang, Xiaodong Wang, Zhenhua Department of Thermal Engineering University of Science and Technology Beijing Beijing 100083 China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing 102206 China Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy North China Electric Power University Beijing 102206 China Xi'an Shaangu Power Co. LTD Xi'an 710075 China

Based on selecting the proper formulas of thermal conductivity and viscosity for nanofluids, a three-dimensional fluid-solid conjugated model was developed to analyze the effect of the heat sink structure, the nanoparticle kind, diameter and volume fraction, and the base fluid kind on the cooling performance of microchannel heat sink. The results showed that: (1) thermal dispersion effect caused by nanoparticle random motion enhanced the thermal convection of nanofluid thus enhances significantly the cooling performance of heat sink;(2) the enhancement of nanofluids was closely dependent on the heat sink structure and the dependence was distinct from the pure fluid, hence the heat sink structure was needed to be optimized for nanofluids as coolants;(3) as the nanoparticle volume fraction increases, the thermal resistance reduced and the pressure increased, the water-based Al2O3 nanofluid with 0.5% volume fraction was the optimal coolant which caused 10.1% decrease in the thermal resistance and only 0.38% increased in the pressure drop;(4) although the nanoparticle size had a small effect on the thermal resistance, nanoparticles with small diameter were recommended with consideration of stability of nanofluids;(5) Al2O3 nanoparticle was superior to TiO2 and CuO, and water was the better base fluid than ethylene glycol and engine oil.

关键词： Nanoparticles

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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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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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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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