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作者： Zhen, H.S. Leung, C.W. Cheung, C.S. Huang, Z.H. Department of Mechanical Engineering Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong State Key Laboratory of Multiphase Flows in Power Engineering Xi'An Jiaotong University Xi'an 710049 China

Experimental study is conducted to clarify the effects of hydrogen addition to biogas and hydrogen fraction in the biogas-H2 mixture on the stability, thermal and emission characteristics of biogas-H2-air premixed flames using a 9 mm-ID-tube Bunsen burner. Variation in biogas composition is allowed to range from BG60 (60%CH4- 40%CO2), down to BG50 (50%CH4-50%CO 2) and to BG40 (40%CH4-60%CO2). For each biogas, the fraction of hydrogen in the biogas-H2 mixture is varied from 10% to 50%. The results show that upon hydrogen addition and increasing hydrogen fraction in the fuel mixture, there are corresponding changes in flame stability, laminar burning velocity, flame tip temperature and CO pollutant emission. Under the tested conditions of 400 ≤ Re ≤ 800 and 0.8 ≤ φ ≤ 1.2, the otherwise incombustible biogas-air mixture becomes flammable upon hydrogen addition and the threshold value of hydrogen fraction for occurrence of stable flames increases with the increase in the CO concentration of biogas. Overall, the flame stability is best at rich equivalence ratio of φ = 1.2. The laminar burning velocity of the biogas-H2-air mixture is found to be higher than pure biogas due to addition of hydrogen, and it monotonically increases at higher hydrogen fraction. Further, a shift in equivalence ratio for peak laminar burning velocity from stoichiometric ≤ = 1.0 to φ = 1.2 is observed. The results also show a monotonic increase in flame temperature and a monotonic decrease in CO emission at higher hydrogen fraction. The more efficient oxidation of CO into CO2 reveals that more complete combustion is induced by hydrogen addition. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Velocity

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Three-dimensional steady calculation on two-phase flow in secondary side of steam generator

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Hedongli Gongcheng/Nuclear power engineering 2014年第2期35卷 37-40页

作者： Cong, Tenglong Tian, Wenxi Qiu, Suizheng Su, Guanghui Xie, Yongcheng Yao, Yangui Department of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Shanghai Nuclear Engineering Research and Design Institute Shanghai 200233 China

Secondary side two-phase flow in steam generator was simulated based on the porous media model. Additional momentum and energy source terms were appended to the momentum and energy equations of porous media region, respectively. The additional momentum source contained the resistances of downcomer, tube bundle, support plate and separator. The additional energy source included the heat transfer from primary side to secondary side fluid. Solving the control equations by ANSYS FLUENT solvers yielded the distributions of velocity, temperature, pressure, density and quality. The distributions of velocity, void fraction and mixture density in hot side vary significantly from these in cold side;the void fraction at the inlet of separator differs from 0.63 to 0.98;pressure descends along axial direction, while at the positions of support plates, pressure declines sharply.

关键词： Porous materials

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Tandem cylinder flow and noise control 20

Tandem cylinder flow and noise control

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20th AIAA/CEAS Aeroacoustics Conference 2014

作者： Liu, Hanru Azarpeyvand, Mahdi Wei, Jinjia Ilário da Silva, Carlos R. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China Mechanical Engineering Department University of Bristol BS8 1TR United Kingdom EMBRAER S.A. São José dos Campos São Paulo Brazil

ISBN: (数字)9781624102851

ISBN: (纸本)9781624102851

This paper is concerned with the application of porous coatings as a passive flow control method for reducing the aerodynamic sound from cylinders in tandem. The aim here is to perform a parametric proof-of-concept study to investigate the effectiveness of porous treatment on bare tandem cylinders to control and regularize the vortex shedding and flow within the gap region between the two bluff bodies, and thereby control the aerodynamic sound generation mechanism. The aerodynamic simulations are performed using 2D transient RANS approach with k-ω transitional turbulence model and the acoustic computations are carried out using the standard Ffowcs Williams-Hawkings (FW-H) acoustic analogy. Numerical flow and acoustic results are presented for bare tandem cylinders and porous-covered cylinders, with different porosities and thicknesses. Experimental flow and acoustic data are also provided for comparison. Results show that the proper use of porous coatings can lead to robust control of the flow within the gap region, the turbulence level and interaction with the downstream body, and therefore the generation of tonal and broadband noise. It has also been observed that the magnitude and the frequency of the primary tone reduce significantly as a result of the flow regularization. Preliminary experimental results are also provided for a single cylinder, confirming that the use of porous covers can effectively control the lift fluctuation near the primary vortex shedding tone.

关键词： Vortex shedding

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Analysis of the loss of pool cooling accident in a PWR spent fuel pool with MAAP5

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Annals of Nuclear Energy 2014年 72卷 198-213页

作者： Xiaoli Wu Wei Li Yapei Zhang Wenxi Tian Guanghui Su Suizheng Qiu State Key Laboratory of Multiphase Flow in Power Engineering School of Nuclear Science and Technology Xi’an Jiaotong University No. 28 Xianning West Road Xi’an Shanxi 710049 China

The Fukushima Daiichi nuclear accident shows that it is necessary to study potential severe accidents and corresponding mitigation measures for the spent fuel pool (SFP) of a nuclear power plant (NPP). This paper presents the analysis of loss of pool cooling accident scenarios and the discussion of mitigation measures for the SFP at a pressurized water reactor (PWR) NPP with the MAAP5 code. Analysis of uncompensated loss of water due to the loss of pool cooling with different initial pool water levels of 12.2 m (designated as a reference case) and 10.7 m have been performed based on a MAAP5 input model. Scenarios of the accident such as overheating of uncovered fuel assemblies, oxidation of claddings and hydrogen generation, loss of intactness of fuel rod claddings, and release of radioactive fission products were predicted with the assumption that mitigation measures were unavailable. The results covered a broad spectrum of severe accident evaluations in the SFP. Furthermore, as important mitigation measures, the effects of recovering the SFP cooling system and makeup water in SFP on the accident progressions have also been investigated respectively based on the events of pool water boiling and spent fuels uncovery. Based upon the reference case, three cases with the recovery of SFP cooling system and three other cases with makeup water in SFP have been studied. The results showed that, severe accident might happen if SFP cooling system was not restored timely before the spent fuels started to become uncovered; spent fuels could be completely submerged and severe accident might be avoided if SFP makeup water system provided water with a mass flow rate larger than the average evaporation rate defined as the division of pool water mass above the top of the spent fuel assemblies by the amount of time to start uncovering the spent fuel assemblies when no mitigation measures were taken. Although spent fuel assemblies were partly exposed due to the mass flow rate of

关键词： Spent fuel pool MAAP5 Loss of pool cooling accident Mitigation measures

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A-Novel-CdS-Nanorod with Stacking Fault Structures: Preparation and Properties of Visible-Light-Driven Photocatalytic Hydrogen Production from Water Splitting

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Energy Procedia 2014年 61卷 2450-2455页

作者： Kai He Liejin Guo International Research Centre for Renewable Energy & State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi 710049 China (Kai He will present the paper at the conference)

In the present study, CdS nanorod particles with the stacking fault structures were hydrothermally synthesized through a dissolution-recrystallization approach in concentrated ammonia solvent, for the first time. It was clear that concentrated ammonia solution contained a large number of hydroxyl ions and large numbers of ammonia. Comprehensive characteristics were performed to investigate the influence of stacking fault structures on the photocatalytic activity and stability of CdS nanorod particles. Transmission electron microscopy (TEM) images revealed that the CdS catalyst included many nanorods with stacking fault structures. Stacking fault structures were obviously observed within CdS nanorods with the length ranging from 70 to 200 nm and diameter ranging from 20 to 65 nm, respectively. It revealed that the formation of CdS nanorod particles with stacking faults was contributed to the dissolution-recrystallization process. There were many structural units for cubic phase changing to hexagonal phase in the CdS crystals in the process of hydrothermal resulting in forming a large number of stacking fault structures. Photo-generated electrons and holes migrating directionally along the nanorods direction and the stacking fault structures in some nanorods could promote the separation of photo-generated electrons and holes, which enhanced the activity of visible-light-driven photocatalytic hydrogen production. Through the photocatalytic hydrogen production experiments, CdS nanorod particles with the stacking fault structures showed much higher photocatalytic activity than CdS patticles prepared by the conventional hydrothermal method using the water as the hydrothermal solvent.

关键词： CdS Nanorods Stacking fault structures Photocatalytic hydrogen production

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FUNCTIONALIZED MODIFICATION TO G-C3N4 FOR EFFICIENT PHOTOCATALYTIC HYDROGEN GENERATION: ENHANCED OPTICAL ABSORPTION AND PROMOTED CHARGE SEPARATION

FUNCTIONALIZED MODIFICATION TO G-C3N4 FOR EFFICIENT PHOTOCAT...

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10th IUPAC International Conference on Novel Materials and their Synthesis NMS-X(IUPAC第十届新材料及其合成国际会议)

作者： S.SHEN J.CHEN International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi''an Jiaotong UniversityShaanxi 710049China

Metal oxide or metal nanodots modified g-C_3N_4 was fabricated using a facile evaporation-annealing method. The effect of metal oxide or metal nanodots decoration on the rate of visible-light (λ ＞ 420 nm) photocatalytic activity was studied by hydrogen production from triethanolamine (TEOA) aqueous solutions. The highest photocatalytic activity was observed on Cu(0.05wt%)/g-C_3N_4 with the hydrogen evolution rate of 241.3 μmolh~(-1)g~(-1), which exceeded that of pure g-C_3N_4 (141.6 μmolh~(-1) g~(-1) ) by more than 70%. The mechanism for the enhanced visible-light photocatalytic activity of g-C_3N_4 decorated with metal oxide or metal nanodots was carefully investigated. For the metal oxide nanodots decorated g-C_3N_4, the improved photocatalytic activity could be contributed to the promoted charge carrier transfer ability, as revealed by time-resolved photoluminescence emission decay spectra; for the metal nanodots decorated g-C_3N_4 (e.g. Ag@SiO_2/g-C_3N_4), the enhanced visible light absorption induced by plasmon effect greatly contributed to the improved photocatalytic activity for hydrogen production.

关键词： g-C3N4 optical absorption charge separation

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Experimental study on the vascular thermal response to visible laser pulses 15

Experimental study on the vascular thermal response to visib...

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15th International Heat Transfer Conference, IHTC 2014

作者： Li, D. Chen, B. Wu, W.J. Wang, G.X. He, Y.L. Ying, Z.X. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi710049 China Department of Mechanical Engineering University of Akron AkronOH44325-3903 United States Laser Treatment Center Department of Dermatology 2nd Affiliated Hospital Medical School Xi'an Jiaotong University Xi'an Shaanxi710004 China

Port Wine Stains (PWS) are congenital vascular malformations that progressively darken and thicken with age and laser therapy is most effective in clinical practice. Using dorsal skin chamber, this study evaluated thermal response of blood vessel to a 595 nm pulsed dye laser (PDL) with controlled energy doses and pulse durations. Totally 32 vessels (30∼300 μm in diameter) are selected from the dorsal skin of the mouse to match those in port wine stain. The experimental results showed that the thermal response of the blood vessels to laser irradiation can be recognized as coagulation, constriction with diameter decrease, disappearance, hemorrhage and collagen damage in the order of increasing laser incident fluence. Blood vessels with small diameter would response poor and survive from the laser heating because their thermal relaxation time is much shorter than the pulse duration. For PDL, vessel hemorrhage is the dominant thermal responses that appear in 15 of 32 blood vessels, and the consequent purpura can be used as treatment endpoint in clinical practice for 595nm PDL. The optimal incident fluence is from 10 to 12 J/cm2 under 6 ms pulse duration without considering the epidermal light absorption, while the optimal pulse duration is 6ms which is close to the thermal relaxation time of the blood vessels with average diameter of 110 μm.

关键词： Medical applications

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Understanding the Initial Decomposition Pathways of the n-Alkane/Nitroalkane Binary Mixture

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Chinese Journal of Chemistry 2013年第8期31卷 1087-1094页

作者： Yulei Guan Ying Zhang Chunhai Yi Bolun Yang Department of Chemical Engineering State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shannxi 710049 China

Addition of nitroalkanes into n-alkanes can lower the activation barriers of free-radical production and acceler- ate the decomposition of n-alkanes at relatively low temperatures. Four initial decomposition mechanisms of the n-butane/nitroethane binary mixture were proposed for the promoting effect and considered theoretically at the B3LYP, BB1K, BMK, MPW1K, and M06-2X levels with MG3S basis set. Energetics above was compared to high-level CBS-QB3 and G4 calculations. Calculated results confirm the feasibility of the four initial decomposition pathways：（I） the C--NO2 bond rupture of nitroethane to produce ethyl and .NO2, （II） HONO elimination from nitroethane followed by decomposition to .OH and .NO, （1II） rearrangement of nitroethane to ethyl nitrite which further dissociates into CH3CH20. and .NO, and （IV） direct hydrogen-abstraction ofnitroethane with n-butane.

关键词： free radical initial decomposition mechanism computational chemistry hydrogen-abstraction bimol-ecular

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Optimization of crucial parameters for double-layer microchannel heat sink

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2014年第3期35卷 567-570页

作者： Lin, Lin Chen, Yang-Yang Wang, Xiao-Dong School of Mechanical 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

As compared with single-layer microchannel heat sink (SL-MCHS), double-layer microchannel heat sink (DL-MCHS) can significantly improve the temperature uniformity of electric elements. This work uses a three-dimensional solid-fluid conjugate model incorporated with a progressive optimization procedure to optimize the cooling performance of a water-cooled, silicon-based DL-MCHS. Four geometric parameters (channel number N, bottom channel height Hc1, upper channel height Hc2, and vertical rib width Wr) and coolant velocity ratio of upper channel to bottom channel, t, are selected as optimized variables. The results show that at a fixed pumping power of 0.05 W and a heat fluxes qw=100 W·cm-2, the optimal geometric structure and coolant velocity ratio for the DL-MCHS are Nopt=70, Hc1,opt=200 μm, Hc2,opt=650 μm, Wr,opt=71.48 μm, and topt=1.85. The thermal resistance of the optimal DL-MCHS is reduced by 11.3% compared to the SL-MCHS, and the maximum temperature difference is reduced to 0.5 K, which is far less than 4.2 K of the SL-MCHS.

关键词： Heat resistance

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Enhanced photodynamic therapy of mixed phase TiO2（B）/anatase nanofibers for killing of HeLa cells

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Nano Research 2014年第11期7卷 1659-1669页

作者： Shuchao Zhang Dongjiang Yang Dengwei Jing Hongwei Liu Long Liu Yi Jia Meihua Gao Liejin Guo Ziyang Huo Department of Blood Transfusion the Affifiated Hospital of Medical College Qingdao University Oingdao 266003 China Department of Immunology Medical College of Qingdao University Qingdao266000 China Collaborative Innovation Centre for Marine Biomass Fibers Materials and Textiles of Shandong Province College of Chemical and Environmental Engineering Qingdao University Qingdao China Queensland Micro- and Nanotechnology Centre (QMNC) Griffith University Nathan Brisbane QLD 4111 Australia International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering College of Chemistry Chemical and Environmental Engineering Xi'an Jiaotong University Xi'an 710049 China Australian Centre for Microscopy and Microanalysis (ACMM) the University of Sydney Sydney NSW 2006 Australia

Photodynamic therapy （PDT）, which is a procedure that uses photosensitizing drug to apply therapy selectively to target sites, has been proven to be a safe treatment for cancers and conditions that may develop into cancers. Nano-sized TiO2 has been regarded as potential photosensitizer for UV light driven PDT. In this study, four types of TiO2 nanofibers were prepared from proton tri-titanate （H2T3O7） nanofiber. The as-obtained nanofibers were demonstrated as efficient photosensitizers for PDT killing of HeLa cells. MTT assay and flow cytometry （FCM） were carried out to evaluate the biocompatibility, percentage of apoptotic cells, and cell viability. The non-cytotoxicity of the as-prepared TiO2 nanofibers in the absence of UV irradiation has also been demonstrated. Under UV light irradiation, the TiO2 nanofibers, particularly the mixed phase nanofibers, displayed much higher cell-killing efficiency than Pirarubicin （THP）, which is a common drug to induce the apoptosis of HeLa cells. We ascribe the high cell- killing efficiency of the mixed phase nanofibers to the bandgap edge match and stable interface between TiO2（B） and anatase phases in a single nanofiber, which can inhibit the recombination of the photogenerated electrons and holes. This promotes the charge separation and transfer processes and can produce more reactive oxygen species （ROS） that are responsible for the killing of HeLa cells.

关键词： photodynamic therapy titanium oxides （TiO2） nanomaterials apoptosis mixed phase

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