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Effect of anisotropic electron transfer on the reactive nucleation of oxide nanowires

CHEMICAL PHYSICS LETTERS 2020年 750卷 137505-137505页

作者： Zheng, Yao-Ting He, Min Cheng, Guang-xu Zhang, Zaoxiao Tan, Jianping Xuan, Fu-Zhen Wang, Zhengdong Xi An Jiao Tong Univ Sch Chem Engn & Technol State Key Lab Multiphase Flow Power Engn Xian Peoples R China East China Univ Sci & Technol Minist Educ Key Lab Pressure Syst & Safety Shanghai Peoples R China

The traditional wisdom that the transfer of electron is isotropic across the oxide layer in Cabrera-Mott model, is powerless in the explanation of reactive nucleation of oxide NWs. In the study, the effect of electron transfer on the dissociation reaction around the tip of oxide NWs is uncovered using molecular dynamics simulation. Based on the simulation, a tip-reaction model is proposed in the interpretation of nucleation of oxide NWs and verified by kelvin probe force microscopy testing. The anisotropy of electron transfer across the oxide layer is found to play a key role in the reactive nucleation of oxide NWs.

关键词： Oxide nanowire Surface Electron transfer Nucleation Kelvin probe force microscopy

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Particle-Scale Modelling of Injected Hydrogen and Coke Co-Combustion in the Raceway of an Ironmaking Blast Furnace

SSRN

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SSRN 2022年

作者： Dianyu, E. Zhou, Peng Ji, Langyong Cui, Jiaxin Xu, Qiang Guo, Liejin Yu, Aibing International Institute for Innovation Jiangxi University of Science and Technology Ganzhou341000 China Jiangxi Provincial Key Laboratory for Simulation and Modelling of Particulate Systems Jiangxi University of Science and Technology Ganzhou341000 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China ARC Research Hub for Computational Particle Technology Department of Chemical Engineering Monash University VIC3800 Australia Centre for Simulation and Modelling of Particulate Systems Southeast University Monash University Joint Research Institute Suzhou215123 China

Hydrogen is an environmentally friendly fuel that does not produce greenhouse gas (GHG) emissions. Its applications have attracted significant attention from many industries, especially the ironmaking industry, which consumes massive amounts of fossil energy. The injection of hydrogen into a blast furnace (BF) is one of the most promising low-carbon ironmaking routines. In this study, an experimentally validated CFD-DEM model is adopted to investigate the dynamics, microstructure and thermochemical behaviours in the raceway of a BF with hydrogen injection operations (HIOs), which include raceway evolution, force distribution and the co-combustion characteristics of hydrogen and coke. Some significant features are obtained through comparison analyses between HIOs and air injection operations (AIOs). In particular, the effects of the hydrogen injection concentration on the raceway size, gas temperature and components are studied. The simulation results show that a smaller raceway is formed under HIOs in comparison with that of AIOs. In addition, the gas temperature is higher near the tuyere but lower along the tuyere axis, and the oxygen consumption is larger and produces more CO. As the hydrogen injection concentration increases: (i) the raceway size and gas temperature decrease;(ii) the CO is generated at the early stage and the maximum CO2 concentration moves to inlet direction along the tuyere axis. The results provide insights on the fundamental understanding of low-carbon ironmaking BF technology. © 2022, The Authors. All rights reserved.

关键词： Blast furnaces

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Study on combustion and emission characteristics of a heavy-duty gas turbine combustor fueled with natural gas

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FUEL 2020年 275卷 117988-117988页

作者： Zeng, Wen Pang, Liyao Zheng, Weilin Hu, Erjiang Shenyang Aerosp Univ Liaoning Key Lab Adv Test Technol Aerosp Prop Sys Shenyang 110136 Liaoning Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shanxi Peoples R China

In this paper, the ignition delay and laminar combustion characteristics of natural gas were tested in a chemical shock tube and a constant volume combustion reactor, respectively, and simulated with the Gri_3.0, USC_2.0 and NUI_Galway models, respectively. It is proved that the ignition delay and laminar combustion characteristics of natural gas simulated with the Gri_3.0 model are in better agreement with the experiment than the USC_2.0 and NUI_Galway models. Furthermore, the simulated variation trends of the mole fractions of main species, especially NO and NO2 with temperature by the Gri_3.0 model are in better agreement with the experimental data in the oxidation of natural gas. The combustion process and pollutants generation characteristics in a single flame tube of a heavy-duty gas turbine burning natural gas were simulated by coupling the Gri_3.0 model with the computational fluid dynamics. It is shown that the simulated average temperature and the NOx concentration at the outlet of the flame tube are slightly higher than the experimental value by 8.06% and 5.08%, respectively. Because the NOx emission is higher than the designed value, fuel flows in the annular, main, and pilot combustion zones of the flame tube were reassigned and effects of the fuel redistributions on the NOx emission characteristics were investigated. It is shown that the NOx concentration at the outlet of the flame tube increases from 157.1 mg/m(3) to 175.5 mg/m(3) when the fuel flow in the pilot combustion zone is redistributed to the main combustion zone, and decreases from 157.1 mg/m(3) to 139.51 mg/m(3) when the fuel flow in the pilot combustion zone is redistributed to the annular combustion zone. The research results will provide theoretical basis and technical support for the optimization of this gas turbine operation.

关键词： Heavy-duty gas turbine Natural gas Combustion characteristics Emission characteristics Staged combustion

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A two-dimensional mathematical model for vanadium redox flow battery stacks incorporating nonuniform electrolyte distribution in the flow frame

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APPLIED THERMAL engineering 2019年 151卷 495-505页

作者： Zhang, B. W. Lei, Y. Bai, B. F. Xu, A. Zhao, T. S. Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Hong Kong Univ Sci & Technol HKUST Energy Inst Dept Mech & Aerosp Engn Hong Kong Peoples R China

Lumped models have been widely adopted to predict the performance of the vanadium redox flow battery (VFRB) stack, which mainly due to its simplicity in modeling transient behaviors during operation cycles. However, average transport and electrochemical properties in previous lumped models make it impossible to obtain the information of electrolyte distributions in stacks. To address this issue, in this work, we report a two-dimensional mathematical model for a VRFB stack considering the effect of nonuniform electrolyte distributions in the flow frame via a flow network equivalence method. With this new model, battery performance and its temperature at different operating conditions are determined accurately. It is demonstrated that (i) temperature fluctuations of the stack reach up to 10 K at different current densities and flow rates;(ii) 25% blockage in the middle cell can lead to the capacity reduction by up to 80%.

关键词： Vanadium redox flow battery stack Battery thermal management Two-dimensional thermal model Nonuniform electrolyte distribution

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Failure Analysis of Tube-Burst on T91 Platen Superheater of 600 MW Supercritical Boiler

Failure Analysis of Tube-Burst on T91 Platen Superheater of ...

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Artificial Intelligence and Electromechanical Automation (AIEA), International Conference on

作者： Ke Sun Jia'an Wang Yu Yan Jiahao Jiang Lei Deng State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an China China Huadian Electric Power Research Institute Co. Ltd. Hangzhou China

ISBN: (数字)9781728182889

ISBN: (纸本)9781728182896

In this paper, the specimen of the bursting tubes, original tube and oxide-like debris are analysed in-depth by macroscopic examination, chemical composition analysis, mechanical properties, metallographic examination, scanning electron microscopy and energy spectrum analysis etc.,. It shows that the main reason for the tube-burst is that the original oxide matters or time-original oxide matters blocks the tube, reducing the cooling effect of the steam, and resulting in a short-term overheating of the tube. It is recommended to control the internal cleanliness of boiler equipment and pipest.

关键词： component tube burst failure analysis oxide matters over temperature FAILURE ANALYSIS excess temperature platen superheater Energy Dispersive X-Ray Spectroscopy oxides Cooling effects tube reducing

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Hierarchical zeolite enveloping Pd-CeO2 nanowires: An efficient adsorption/catalysis bifunctional catalyst for low temperature propane total degradation

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CHEMICAL engineering JOURNAL 2020年 393卷 124717-124717页

作者： Dong, Tao Liu, Wenming Ma, Mudi Peng, Honggen Yang, Senyou Tao, Jinxiong He, Chi Wang, Liang Wu, Peng An, Taicheng Nanchang Univ Coll Chem Key Lab Jiangxi Prov Environm & Energy Catalysis 999 Xuefu Rd Nanchang 330031 Jiangxi Peoples R China Xi An Jiao Tong Univ Sch Energy & Power Engn State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Guangdong Univ Technol Inst Environm Hlth & Pollut Control Sch Environm Sci & Engn Guangdong Key Lab Environm Catalysis & Hlth Risk Guangzhou 510006 Peoples R China Univ Chinese Acad Sci Natl Engn Lab VOCs Pollut Control Mat & Technol Beijing 101408 Peoples R China Zhejiang Univ Coll Chem & Biol Engn Minist Educ Key Lab Biomass Chem Engn Hangzhou 310027 Peoples R China East China Normal Univ Dept Chem & Mol Engn Shanghai Key Lab Green Chem & Chem Proc North Zhongshan Rd 3663 Shanghai 200062 Peoples R China

Volatile organic compounds (VOCs) are significant ozone (O-3) and particulate matter (PM) formation precursors and are deleterious to both human health and environment. Catalytic combustion can degrade VOCs to H2O and CO2 without secondary pollution, suggesting a potential sustainable technology for air pollution control. However, the concentration of exhausted VOCs is usually too low for effective decomposition. Herein, a novel adsorption/catalysis bifunctional catalyst, hierarchical silicalite-1 (S-1) zeolite enveloping Pd-CeO2 nanowires (Pd-CeO2NW@S-1), was designed and prepared using a simple one-pot two-step method and applied for the degradation of propane. Pd-CeO2NW@S-1 exhibited superior catalytic activity (T-90 decreased to 296 degrees C) as well as increased thermal and hydrothermal stability (no obviously decrease in activity when treated at 700 degrees C or reacted with water gas, respectively) compared with Pd-CeO2 nanowires supported on the outer surface of S-1 (Pd-CeO2NW/S-1) and previously reported Pd based catalysts for propane degradation. In addition, the activity over Pd-CeO2NW@S-1 after five reaction cycles just with little decrease and could be restored by a simple regeneration step and without any detection of coke. The remarkable performance over Pd-CeO2NW@S-1 was attributed to the high dispersion of Pd and Ce encapsulated in hierarchical zeolite with superior propane adsorption performance and the special confinement structure according the Mars-van-Krevelen (MvK) mechanism. This confinement adsorption/catalysis bifunctional strategy can be used to design other high-performance catalysts for degradation of VOCs.

关键词： Volatile organic compounds Catalytic combustion Propane total degradation Zeolite confinement Sinter resistance Adsorption/catalysis bifunctional catalyst

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Analysis of Frequent Tube Burst of High Temperature Reheater in 600 MW Unit

Analysis of Frequent Tube Burst of High Temperature Reheater...

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Sustainable power and Energy Conference (iSPEC)

作者： Ke Sun Jia'an Wang Yu Yan Jiahao Jiang Lei Deng Defu Che China Huadian Electric Power Research Institute Co. Ltd. Hangzhou China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an China

ISBN: (数字)9781728191645

ISBN: (纸本)9781728191652

The reasons of frequent tube burst of the high temperature reheater in a supercritical 600 MW unit were systematically investigated via the examination of macroscopic inspection, chemical composition, mechanical properties, microstructures, scanning electron microscope and energy disperse spectroscopy detection. It is demonstrated that the tube burst of the high temperature reheater results from not only design factors, but also manufacture quality. Due to the absence of solid solution treatment in spare elbow, the inner dislocations and residual stress increase obviously, which accelerates the precipitation of carbide containing Cr and the formation of Cr depleted zone on grain boundary(GB) subsequently, leading to the decrease of GB corrosion resistance and the final leakage of high temperature reheater tube induced by intergranular corrosion.

关键词： Temperature Corrosion Welding Electron tubes Residual stresses Acceleration Elbow

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High spatio-temporal heterogeneity of carbon footprints in the Zhejiang Province, China, from 2005 to 2015: implications for climate change policies

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ENVIRONMENTAL CHEMISTRY LETTERS 2020年第3期18卷 931-939页

作者： Zheng, Sheng Shan, Jiaming Singh, Ramesh P. Wu, Yuzhe Pan, Jiachen Wang, Yueshe Lichtfouse, Eric Zhejiang Univ Dept Land Management Hangzhou 310058 Peoples R China Chapman Univ Schmid Coll Sci & Technol Sch Life & Environm Sci One Univ Dr Orange CA 92866 USA Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Aix Marseille Univ CNRS Coll France IRDINRAECEREGE F-13100 Aix En Provence France

Energy consumption is a major factor influencing climate change. Low-carbon strategies can be defined from carbon (C) footprint and ecological pressure caused by energy consumption. We hypothesized that this should be done at the regional and city levels because factors controlling C footprints vary with location and time, yet there is actually little knowledge at local levels. Here, we mapped the C emissions and footprint of 11 cities in the Zhejiang Province of China, a rapidly growing area of about 57 million inhabitants, which is representative of the strong economic growth in China. The C footprint is expressed as the land surface necessary to adsorb C emissions. We studied spatio-temporal evolution of C footprints from 2005 to 2015 using the center of gravity method. Results show that total annual C emissions due to energy consumption in Zhejiang increased by 40.83 million tons (55.8%) from 2005 to 2011. Then, from 2011 to 2015, C emissions decreased by 5.8%, which is explained by the 5-year national plan aiming at decreasing emissions. Similarly, the total C footprint increased by 55.8% from 29,201,904 hm(2) in 2005 to 45,496,817 hm(2) in 2011 and then declined by 5.8% from 2011 to 2015. At the city level, Ningbo has the largest C footprint contribution, whereas Lishui the lowest. Zhoushan shows an increase in C emissions and footprint, whereas Hangzhou and Shaoxing show a decline. The center of gravity of the C footprint is located in Shaoxing and is moving southeast from 2006 to 2011. Overall, our findings reveal the high spatial heterogeneity of C footprint at the regional and city levels, implying that national low-carbon strategies should be adapted at lower levels for higher efficiency.

关键词： Spatio-temporal heterogeneity Energy consumption Carbon footprint Zhejiang Province

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Modeling of the filtered drag force in gas-solid flows via a deep learning approach

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CHEMICAL engineering SCIENCE 2020年 225卷 115835-115835页

作者： Zhang, Yu Jiang, Ming Chen, Xiao Yu, Yaxiong Zhou, Qiang Xi An Jiao Tong Univ Sch Chem Engn & Technol Xian 710049 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

A deep learning approach based on a proposed artificial neural network (ANN) is exploited to predict the filtered drag force, which is a desirable term for coarse-grid simulations of gas-solid flows. The proposed ANN model includes one input layer, five hidden layers and one output layer. The hidden layers are composed of three convolutional layers and two fully-connected layers. The results show that the proposed ANN model is superior to the multi-layered perceptron (MLP) model and the best available traditional functional model over a wide range of the filter size. The results also indicate that the use of the information on neighboring coarse grids is necessary for accurate estimation of the filtered drag force at the considered filter sizes. This finding is substantiated by a budget analysis which demonstrates that the diffusion of the Reynolds stress and solid phase stress significantly affects the filtered drag force. (c) 2020 Elsevier Ltd. All rights reserved.

关键词： Gas-solid flow Meso-scale structure Artificial neural network Two-fluid model Drag force

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Electrostatic-field-triggered stress in the lithiation of carbon-coated silicon

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JOURNAL OF power SOURCES 2020年 459卷 228100-228100页

作者： Zheng, Yao-Ting He, Min Cheng, Guang-xu Zhang, Zaoxiao Xuan, Fu-Zhen Wang, Zhengdong Xi An Jiao Tong Univ Sch Chem Engn & Technol State Key Lab Multiphase Flow Power Engn Xian Peoples R China East China Univ Sci & Technol Key Lab Pressure Syst & Safety Minist Educ Shanghai Peoples R China

The traditional viewpoint "the more the lithiation reaction, the bigger the growth stress" is proved to be improper through the simulation of lithiation reaction of carbon-coated silicon particle in the presence of electrostatic field. In the simulation, a positive correlation between growth stresses and charge density is observed and coincides with the experiment results in Pharr's work. Simulation results also indicate that the growth stresses consist of lithiation-reaction-induced stress (LRIS) and field-triggered stress (FTS). FTS is always neglected but can be comparable to, or even bigger than the LRIS in the initial stage of lithiation reaction. The physical mechanism for the formation of FTS is uncovered based on the standpoint of energy conservation and transformation. The FTS needs to be considered seriously because it can bring much more serious damage to the lattice structure of silicon especially in the development of lithium ion battery featuring rapid charging.

关键词： Ultrafast charging Electrostatic field Growth stress Lithiation

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