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Chemical characteristics of size-resolved aerosols in winter in Beijing

Journal of Environmental Sciences 2014年第8期26卷 1641-1650页

作者： Kang Sun Yu Qu Qiong Wu Tingting Han Jianwei Gu Jingjing Zhao Yele Sun Qi Jiang Ziqi Gao Min Hu Yuanhang Zhang Keding Lu Stephan Nordmann Yafang Cheng Li Hou Hui Ge Masami Furuuchi Mitsuhiko Hata Xingang Liu State Key Laboratory of Water Environment Simulation School of EnvironmentBeijing Normal University College of Environmental Sciences and Engineering Peking University State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of Sciences Environmental Science Center University of Augsburg School of Foreign Languages China University of Political Science and Law School of Chemistry Beijing Normal University Multiphase Chemistry Department Max Planck Institute for Chemistry Laboratory of Atmospheric Environment and Pollution Control Engineering Graduate School of Natural Science & TechnologyKanazawa University

Size-resolved aerosols were continuously collected by a Nano Sampler for 13 days at an urban site in Beijing during winter 2012 to measure the chemical composition of ambient aerosol particles. Data collected by the Nano Sampler and an ACSM（Aerodyne Aerosol Chemical Speciation Monitor） were compared. Between the data sets,similar trends and strong correlations were observed,demonstrating the validity of the Nano Sampler. PM10 and PM2.5concentrations during the measurement were 150.5 ± 96.0 μg/m3（mean ± standard variation）and 106.9 ± 71.6 μg/m3,respectively. The PM2.5/PM10 ratio was 0.70 ± 0.10,indicating that PM2.5dominated PM10. The aerosol size distributions showed that three size bins of 0.5–1,1–2.5 and 2.5–10 μm contributed 21.8%,23.3% and 26.0% to the total mass concentration（TMC）,respectively. OM（organic matter） and SIA（secondary ionic aerosol,mainly SO42-,NO3-and NH4＋） were major components of PM2.5. Secondary compounds（SIA and secondary organic carbon） accounted for half of TMC（about 49.8%） in PM2.5,and suggested that secondary aerosols significantly contributed to the serious particulate matter pollution observed in winter. Coal burning,biomass combustion,vehicle emissions and SIA were found to be the main sources of PM2.5. Mass concentrations of water-soluble ions and undetected materials,as well as their fractions in TMC,strikingly increased with deteriorating particle pollution conditions,while OM and EC（elemental carbon） exhibited different variations,with mass concentrations slightly increasing but fractions in TMC decreasing.

关键词： Aerosol Size distribution Chemical characteristics Beijing

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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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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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Shaped Photocatalysts: Surface Activation of Faceted Photocatalyst: When Metal Cocatalyst Determines the Nature of the Facets (Adv. Sci. 11/2015)

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Advanced Science 2015年第11期2卷 n/a-n/a页

作者： Bin Wang Maochang Liu Zhaohui Zhou Liejin Guo International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow Xi'an Jiaotong University Xi'an Shaanxi 710049 P.R. China

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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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Morphological changes and reduction mechanism for the weak reduction of the preoxidized panzhihua ilmenite

Morphological changes and reduction mechanism for the weak r...

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作者： Zhang, Jianbo Zhang, Gengyu Zhu, Qingshan Lei, Chao Xie, Zhaohui Li, Hongzhong State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China

Morphological changes and phase transition behaviors were investigated for the weak reduction (reduction of ferric iron-to-ferrous state) of preoxidized Panzhihua ilmenite by hydrogen at 873 K to 1073 K (600 °C to 800 °C). Ilmenite was preoxidized for 4 hours at 1023 K and 1173 K (750 °C and 900 °C), respectively, before the reduction. The results revealed that there were two competing reduction routes. At high reduction temperatures, e.g., 1023 K and 1073 K (750 °C and 800 °C), ferric irons from both hematite and pseudobrookite would combine with rutile grains as formed in the preoxidation to form homogeneous ilmenite phase with pores immingled. However, at lower reduction temperatures, e.g., 873 K (600 °C), hematite and pseudobrookite are reduced mainly through direct reduction without the participation of rutile. As a result, the as-reduced ilmenites show great differences in their phase components and microstructure, especially for the Ti species. For ilmenites preoxidized at 1023 K (750 °C), most of the Ti ions present in the needlelike rutile network, but for ilmenites preoxidized at 1173 K (900 °C), Ti distributed in both irregular rutile grains and ilmenite matrix. © 2014 The Minerals, Metals & Materials Society and ASM International.

关键词： Ilmenite

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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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Characterization of biogas-hydrogen premixed flames using Bunsen burner

Characterization of biogas-hydrogen premixed flames using Bu...

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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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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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"what We Breathe Impacts Our Health: Improving Understanding of the Link between Air Pollution and Health"

"what We Breathe Impacts Our Health: Improving Understanding...

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作者： West, J. Jason Cohen, Aaron Dentener, Frank Brunekreef, Bert Zhu, Tong Armstrong, Ben Bell, Michelle L. Brauer, Michael Carmichael, Gregory Costa, Dan L. Dockery, Douglas W. Kleeman, Michael Krzyzanowski, Michal Künzli, Nino Liousse, Catherine Lung, Shih-Chun Candice Martin, Randall V. Pöschl, Ulrich Pope, C. Arden Roberts, James M. Russell, Armistead G. Wiedinmyer, Christine Environmental Sciences and Engineering University of North Carolina at Chapel Hill Chapel HillNC27599 United States Health Effects Institute BostonMA02110 United States European Commission Joint Research Centre Institute for Environment and Sustainability IspraI. 21027 Italy Institute for Risk Assessment Sciences Universiteit Utrecht Julius Center for Health Sciences and Primary Care University Medical Center Utrecht Utrecht3584 CJ Netherlands State Key Lab for Environmental Simulation and Pollution Control College of Environmental Science and Engineering Peking University Beijing100871 China Social and Environmental Health Research London School of Hygiene and Tropical Medicine LondonWC1E 7HT United Kingdom School of Forestry and Environmental Studies Yale University New HavenCT06511 United States School of Population and Public Health University of British Columbia VancouverBCV6T 1Z3 Canada Chemical and Biochemical Engineering University of Iowa Iowa CityIA52242 United States Air Climate and Energy Research Program Office of Research and Development Environmental Protection Agency DurhamNC27705 United States Harvard T. H. Chan School of Public Health BostonMA02115 United States Civil and Environmental Engineering University of California at Davis DavisCA95616 United States Environmental Research Group King's College London LondonSE1 9NH United Kingdom Epidemiology and Public Health Swiss Tropical and Public Health Institute Basel Switzerland University of Basel Basel Switzerland Laboratoire d' Aérologie CNRS-Université de Toulouse Toulouse31400 France Research Center for Environmental Changes Academia Sinica Taipei Taiwan Physics and Atmospheric Science Dalhousie University HalifaxNSB3H 4R2 Canada Harvard-Smithsonian Center for Astrophysics CambridgeMA02138 United States Multiphase Chemistry Department Max Planck Institute for Chemistry Mainz55128 Germany Economics Brigham Young University ProvoUT84602 United States Ea

Air pollution contributes to the premature deaths of millions of people each year around the world, and air quality problems are growing in many developing nations. While past policy efforts have succeeded in reducing particulate matter and trace gases in North America and Europe, adverse health effects are found at even these lower levels of air pollution. Future policy actions will benefit from improved understanding of the interactions and health effects of different chemical species and source categories. Achieving this new understanding requires air pollution scientists and engineers to work increasingly closely with health scientists. In particular, research is needed to better understand the chemical and physical properties of complex air pollutant mixtures, and to use new observations provided by satellites, advanced in situ measurement techniques, and distributed micro monitoring networks, coupled with models, to better characterize air pollution exposure for epidemiological and toxicological research, and to better quantify the effects of specific source sectors and mitigation strategies. © 2016 American Chemical Society.

关键词： Health

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