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Manipulating metal-oxygen local atomic structures in singlejunctional p-Si/WO_(3) photocathodes for efficient solar hydrogen generation

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Nano Research 2021年第7期14卷 2285-2293页

作者： Wu Zhou Chung-Li Dong Yiqing Wang Yu-Cheng Huang Lingyun He Han-Wei Chang Shaohua Shen International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityShaanxi 710049China Department of Physics Tamkang UniversityTamsui 25137TaiwanChina

Self-passivation in aqueous solution and sluggish surface reaction kinetics significantly limit the photoelectrochemical(PEC)performances of silicon-based ***,a WO_(3) thin layer is deposited on the p-Si substrate by pulsed laser deposition(PLD),acting as a photocathode for PEC hydrogen *** to bare p-Si,the single-junctional p-Si/WO_(3) photoelectrodes exhibit excellent and stable PEC performances with significantly increased cathodic photocurrent density and exceptional anodic shift in onset potential for water *** is revealed that the WO_(3) layer could reduce the charge transfer resistance across the electrode/electrolyte interface by eliminating the effect of Fermi level pinning on the surface of *** importantly,by varying the oxygen pressures during PLD,the collaborative modulation of W–O bond covalency and WO6 octahedral structure symmetry contributes to the promoted charge carrier transport and ***,a large band bending at the p-Si/WO_(3) junction,induced by the optimized O vacancy contents in WO_(3),could provide a photovoltage as high as~500 mV to efficiently drive charge transfer to overcome the water reduction ***,by manipulating W–O local atomic structures in the deposited WO_(3) layer,a great improvement in PEC performance could be achieved over the singlejunctional p-Si/WO_(3) photocathodes for solar hydrogen generation.

关键词： silicon local atomic structure water splitting photocathodes hydrogen generation

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Acetic acid-assisted mild dealloying of fine CuPd nanoalloys achieving compressive strain toward high-efficiency oxygen reduction and ethanol oxidation electrocatalysis

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Carbon Energy 2023年第7期5卷 112-120页

作者： Danye Liu Yu Zhang Hui Liu Peng Rao Lin Xu Dong Chen Xinlong Tian Jun Yang State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijingChina State Key Laboratory of Marine Resource Utilization in South China Sea Hainan Provincial Key Lab of Fine ChemistrySchool of Chemical Engineering and TechnologyHainan UniversityHaikouChina Jiangsu Key Laboratory of New Power Batteries School of Chemistry and Materials ScienceJiangsu Collaborative Innovation Centre of Biomedical Functional MaterialsNanjing Normal UniversityNanjingChina Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijingChina Nanjing IPE Institute of Green Manufacturing Industry NanjingJiangsuChina

Dealloying by which the transition metal is partially or completely leached from an alloy precursor is an effective way to optimize the fundamental effects for further enhancing the electrocatalysis of a ***,to address the deficiencies associated with the commonly used dealloying methods,for example,electrochemical and sulfuric acid/nitric acid treatment,we report an acetic acid-assisted mild strategy to dealloy Cu atoms from the outer surface layers of CuPd alloy nanoparticles to achieve high-efficiency electrocatalysis for oxygen reduction and ethanol oxidation in an alkaline *** leaching of Cu atoms by acetic acid exerts an additional compressive strain effect on the surface layers and exposes more active Pd atoms,which is beneficial for boosting the catalytic performance of a dealloyed catalyst for the oxygen reduction reaction(ORR)and the ethanol oxidation reaction(EOR).In particular,for ORR,the CuPd nanoparticles with a Pd/Cu molar ratio of 2:1 after acetic dealloying show a half-wave potential of 0.912 V(***)and a mass activity of 0.213 AmgPd^(-1) at 0.9 V,respectively,while for EOR,the same dealloyed sample has a mass activity and a specific activity of 8.4 Amg^(-1) and 8.23 mA cm^(-2),respectively,much better than their dealloyed counterparts at other temperatures and commercial Pd/C as well as a Pt/C catalyst.

关键词： compressive strain effect dealloying electrocatalysis ethanol oxidation reaction oxygen reduction reaction

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Experimental and Numerical Study on Co-combustion Behaviors and NO_(x) Emission Characteristics of Semi-coke and Coal in a Tangentially Fired Utility Boiler

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Journal of Thermal Science 2021年第4期30卷 1116-1131页

作者： WANG Chang’an FENG Qinqin JIN Liyan WANG Zhichao YAO Wei WANGPengqian DU Yongbo ZHANG Xilai YANG Zhongcan CHE Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an 710049China Xi’an Thermal Power Research Institute Co. LTD.Xi’an 710054China

The utilization of powdery semi-coke as a power fuel in pulverized coal-fired power plants has become a new and potential technique to consume the excess powdery *** characteristic of low volatile results in poor combustion performance and high NO_(x) emission,and to co-fire with bituminous coal is a practical strategy to address this ***,the co-combustion characteristics and the inherent interaction between semi-coke and coal remain insufficiently *** addition,the influences of secondary air arrangement,the boiler operation load,and the fuel type on co-combustion process are still unclear,which is urgent to be further *** the present study,experiments and numerical simulations were jointly utilized to inquire into the co-combustion behaviors and NO_(x) emission features of semi-coke and *** results demonstrated that the"out-furnace method"was a suitable choice for small-capacity boiler when the proportion of semi-coke was 33%,due to the limited combinations of the semi-coke injection *** was recommended that semi-coke was preferred to be injected from the middle layers of the furnace under the"in-furnace method"to improve the overall co-combustion *** critical value of the separated over fire air ratio in this study was 27.5%,over which a slight drop of carbon content in fly ash could come ***,the elevation in the proportion of separated over fire air gave rise to the significant decline of NO_(x) *** constricted secondary air arrangement was preferred to be employed due to the high boiler *** separated over fire air and the surrounding air needed to maintain a wide-open degree to prevent the increase of NO_(x) emissions and the coking of *** the load reduction regulation method adopted in this study,the NO_(x) concentration first rose and then dropped,while the burnout ratio decreased obviously as the operation load was *** combinations of coa

关键词： semi-coke numerical simulation co-combustion NOx emission blending method

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Insights into the microstructural design of high-performance Ti alloys for laser powder bed fusion by tailoring columnar prior-βgrains andα-Ti morphology

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Journal of Materials Science & Technology 2024年第20期187卷 156-168页

作者： S.X.Wang S.F.Li X.M.Gan R.D.K.Misra R.Zheng K.Kondoh Y.F.Yang State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Science and Technology on Particle Materials Chinese Academy of SciencesBeijing 100190China Department of Metallurgical Materials and Biomedical EngineeringUniversity of TexasEl Paso TX 79968USA Joining and Welding Research Institution Osaka University11-1 MihogaokaIbarakiOsaka 567-0047Japan

A high-performance Ti-Ni-B alloy with good tensile properties and reduced mechanical anisotropy was developed by promoting the columnar to equiaxed transition(CET)of prior-βgrains and modifyingα-laths to equiaxed *** Ni and B contributed to the refinement of columnar prior-βgrains during the L→βphase transformation by generating constitutional *** with Ni,B had a su-perior capability of generating constitutional undercooling,which not only replaced a significant amount of Ni with a minor addition to reduce the formation of brittle eutectoid,but also reacted with Ti to form TiB to promote heterogeneous nucleation ofα-Ti grains during theβ→αphase *** with the restricted growth ofα-laths induced by the refinement of prior-βgrains,a fully equiaxedα-Ti structure was *** competition between the negative effect of brittle eutectoid and the positive role ofα-lath to equiaxed grain transition on the ductility of as-printed Ti-Ni-B alloys was fundamen-tally governed by the morphology of eutectoid and technically dependent on the Ni-B *** the addition was 1.2Ni-0.06B(wt.%)or less,the positive effect ofα-lath on equiaxed grain transition can effectively mitigate the issue of reduced ductility caused by brittle *** contrast,at 1.8Ni-0.09B or greater,the negative effect of eutectoid *** insights into microstructural design obtained through the aforementioned approach were presented and discussed.

关键词： Laser powder bed fusion Titanium alloys Grain refinement Powder processing Anisotropy

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Simulation Study on Heat Exchangers Characteristics of Solar Thermal Steam System Based on Aspen Plus 2

Simulation Study on Heat Exchangers Characteristics of Solar...

引用

2nd International Conference on Algorithms, High Performance Computing and Artificial Intelligence, AHPCAI 2022

作者： Chen, Pengfei Chen, Kang Peng, Huaiwu Zhang, Yanlong Bawaa, Baercheng Zhao, Qiuyang Institute of Solar Engineering Technology Northwest Engineering Corporation Limited Power China Xi'an710065 China Xi'An Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an China

ISBN: (纸本)9798350334784

In the thermal recovery project of thick oil, there are high standards for steam temperature and flow rate. The solar thermal steam supply system can convert unstable solar energy into stable and efficient carrier heat, which can be used to transfer heat to low-temperature water to produce high-temperature steam and achieve a clean and low-carbon steam supply. The rated pressure of steam and the split ratio of molten salt in the heating system have a great influence on the demand area and heat load of solar panels. In this paper, a simulation is made on the solar thermal steam supply system based on Aspen Plus. The simulation result shows that the increase in pressure will cause a growth in the area of the photothermal concentrator field but will reduce the area used for photovoltaic panels. At the same time, it reduces the heat load of the evaporator and extends its service life. The split ratio affects the molten salt temperature at the outlet of the superheater and the reheater. When the split ratio increases, the heat transfer temperature difference between the two ends of the superheater heat flow decreases, and the heat transfer temperature difference of the reheater grows bigger. Therefore, the molten salt temperature flowing out of the reheater rises. © 2022 IEEE.

关键词： Heat exchangers

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Multi-physics analysis of the galvanic corrosion of Mg-steel couple under the influence of time-dependent anisotropic deposition film

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Journal of Magnesium and Alloys 2021年第3期9卷 866-882页

作者： Kai Wang Chenpei Li Yanhui Li Jinling Lu Yueshe Wang Xingqi Luo State Key Laboratory of Eco-hydraulics in Northwest Arid Region Xi'an University of TechnologyNo.5 Jinhua South RoadXi'an 710048China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityNo.28 Xianning West RoadXi'an 710049China

The anisotropic deposit film formed during the galvanic corrosion can impede the mass transfer of the involved species,thereby affecting the electro-chemical behavior and the evolution of galvanic *** limitations of experimental studies in the spatial-temporal scales restrict a deeper understanding of the corrosion mechanism,which can be complemented by numerical simulation.A multi-physics coupled model is proposed in this work to systematically investigate the temporal and spatial evolution of galvanic corrosion of the Mg-steel couple with the growing anisotropic deposition *** utilizing the multi-physics field coupled technique,various coupled physical-chemical processes underlying the corrosion behavior are built into the model,including chemical reactions,ionic mass transfer in the bulk solution and the deposition layer,interfacial reaction,deposition of corrosion products as well as the morphological transitions caused by metal dissolution and *** particular,the anisotropic deposit film is considered to be a porous layer with a porosity varying in time and space as the corrosion *** predicted corrosion morphology by this model is better than the previous *** coupled relationship between the electrochemical behavior(e.g.,electrode reaction kinetics,current density,surface potential)and the physical processes(e.g.,ionic transport,geometric evolution of metal surface and film interface)is *** results indicate that a porous deposition layer with a denser inner layer and a loose outer layer is generated,leading to more significant inhibition of mass transfer in the inner layer than the outer *** anisotropism of the deposition layer results in a non-uniform conductivity distribution and a discontinuous current density distribution in the *** current density on the electrode surface is inhibited by the deposition layer and the variation in the cathode/anode area ratio during the corrosion *** c

关键词： Galvanic corrosion Corrosion product film Modeling Mass transport Porosity

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A framework of the transport model for high-order eddy viscosity tensor in two-dimensional turbulent flow

arXiv

引用

arXiv 2023年

作者： Zhou, Xingguang Zhang, Dalin Tian, Wenxi Su, Guanghui Qiu, Suizheng State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'An710049 China

Motivated by the concept of eddy viscosity tensor in improved Boussinesq hypothesis, a transport model of high-order eddy viscosity tensor in 2D-3C turbulence structure is derived from the second-order moment model by tensorial analysis. Compared with the previous high-order eddy viscosity tensor mathematical model [1-3] for turbulent flow under special operating conditions, we have obtained a general high-order eddy viscosity tensor transport model, which can show the anisotropy and transport characteristics of Reynolds stress. The transport equation of a high-order eddy viscosity tensor includes the transient term, convection term, production term, diffusion term, positive-definite source term, and dissipation term. In addition, when the components of high-order eddy viscosity tensor are positive or negative, the physical meaning of the source terms is also discussed. Two numerical simulation cases are also interpreted to verify the model. First, we apply the transport model of high-order eddy viscosity to the numerical calculation analysis of two-dimensional straight channel turbulent flow, and the results show that this model can effectively characterize the anisotropy of Reynolds stress. With a combination of analytical and numerical methods, we analyze the flow fields and the components of high-order eddy viscosity tensor to investigate the evolution law of high-order eddy viscosity tensor. The characteristics of the principal components and tensorial invariance of dimensionless Reynolds stress anisotropy tensor of two-dimensional straight channel turbulent flow also have been investigated with the Lumley triangle [4,5]. The results show that this model has a good agreement with the DNS calculation results for the characteristics of dimensionless Reynolds stress anisotropy tensor. Then, we make the numerical investigation for a two-dimensional planar asymmetric diffuser and compare the results with the experiments of Obi *** [6]. The transport model can reso

关键词： Tensors

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Heat transfer behaviors of some supercritical fluids: A review

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Chinese Journal of Aeronautics 2022年第1期35卷 290-306页

作者： Gongnan XIE Xiaoxiao XU Xianliang LEI Zhouhang LI Yong LI Bengt SUNDEN School of Marine Science and Technology Northwestern Poly technical UniversityXi'an 710072China Key Laboratory of Low-grade Energy Utilization Technologies and Systems Chongqing UniversityChongqing 400044China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization Kunming University of Science and TechnologyKunming 650093China School of Mechanical Engineering Northwestern Polyteclwical UniversityXi'an 710072China Department of Energy Sciences Lund UniversitySE-22100 LundSweden

Supercritical fluids(e.g.,hydrocarbon fuels,water,carbon dioxide,and organic working medium,etc)have been recognized as working media to improve thermal efficiencies in power cycles and energy conversion,and have been used or selected as the working fluids in engineering fields such as aerospace,nuclear power,solar energy,refrigeration,geothermal energy,chemical technology,and so *** better understand the interesting characteristic or abnormal behaviors of supercritical fluids,most valuable research works(including experimental results and numerical studies)from domestic and abroad have been *** such,this paper presents a comprehensive review on heat transfer behaviors of some supercritical fluids in engineering *** review focuses on recently available articles published mainly from 2016 up to the present *** common problems(i.e.,heat transfer enhancement and heat transfer deterioration particularly for the supercritical hydrocarbon fuels)in the supercritical field are summarized and some perspectives on future prospects are also included.

关键词： Heat transfer behavior Supercritical fluids Thermo-physical property Turbulence model Working condition

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A Numerical Approach for Inlet-Outlet Boundary Conditions with Least-Square Moving Particle Explicit (Lsmpe) Method on Gpu

SSRN

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SSRN 2024年

作者： Ren, Qianyong Cao, Sheng Wang, Wenpeng Zhang, Bin Shan, Jianqiang Shaanxi Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

The study introduces a method for managing inlet and outlet boundary conditions using the Least-Square moving particle explicit method (LSMPE). A high-precision least squares discrete method was applied to the moving particle explicit method (MPE) based on predictive-corrected pressure. The code was accelerated using OpenACC for parallelization. Special boundary treatments were applied to minimize errors induced by boundaries, including particle number density correction for inlet particles, addressing slip or nonslip boundaries, and introducing concept particles at the outlet. The stability and accuracy of this method were validated through three cases. Simulation results for Poiseuille flow and circular flow demonstrated the method’s good precision, exhibiting stable pressure fields. Results from single-phase flow simulations through a porous medium bed agreed well with predictions from the Ergun equation, highlighting the method’s potential for practical engineering applications © 2024, The Authors. All rights reserved.

关键词： Porous materials

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Spherical Particles Growth with Dynamic Oscillation during Lithium Electrodeposition

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Energy Material Advances 2023年第1期4卷 112-119页

作者： Hanxu Jing Hui Xing Bohan Li Yongsheng Han MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Northwestern Polytechnical University710129 Xi’anChina Shaanxi Basic Discipline(Liquid Physics)Research Center Northwestern Polytechnical University710129 Xi’anChina State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of Sciences100190 BeijingChina

In this paper,the spherical particles growth during lithium electrodeposition was investigated by directly solving the governing equations based on the Landau transformation *** basic growth kinetic characteristics of a spherical particle during electrodeposition was *** results show that the dynamic oscillation of the growth velocity occurs during the spherical particle *** was found from numerical simulations that applied electrical potential difference,electrolyte concentration,and diffusion coefficient are 3 main factors influencing the spherical growth and the existence of the dynamic oscillation state of the growth velocity during *** increase in both the applied electrical potential difference and the electrolyte concentration can lead to the increase of the growth velocity of the spherical particle,while the growth velocity is independent of the diffusion ***,it was found that the wavelength and the amplitude of the dynamic oscillation of the growth velocity can be influenced by the applied electrical potential difference,the electrolyte concentration,and the diffusion *** determined that the dynamic competition between electrochemical reactions and ion transport in the electrodeposition is the reason for the existence of the oscillation of the growth velocity.

关键词： coefficient. method. oscillation

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