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TiO2-SnO2:F interfacial electronic structure investigated by soft x-ray absorption spectroscopy

Physical Review B 2012年第12期85卷 125109-125109页

作者： Coleman X. Kronawitter Mukes Kapilashrami Jonathan R. Bakke Stacey F. Bent Cheng-Hao Chuang Way-Faung Pong Jinghua Guo Lionel Vayssieres Samuel S. Mao Department of Mechanical Engineering University of California at Berkeley Berkeley California 94720 USA Environmental Energy Technologies Division Lawrence Berkeley National Laboratory Berkeley California 94720 USA Advanced Light Source Lawrence Berkeley National Laboratory Berkeley California 94720 USA Department of Chemical Engineering Stanford University Stanford California 94305 USA Department of Physics Tamkang University Tamsui Taiwan Republic of China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi 710049 People's Republic of China

The electronic structure of the titanium dioxide (TiO2)-fluorine-doped tin dioxide (SnO2:F) interface is investigated by soft x-ray absorption spectroscopy using synchrotron radiation. The measurements probe the site- and symmetry-selected unoccupied density of states and reflect the interaction between an early transition-metal-oxide (d0) semiconductor and a post-transition-metal-oxide (d10) degenerate semiconductor. The distinct interfacial electronic structure of TiO2-SnO2:F is established by contrasting spectra with those for anatase and rutile TiO2, SnO2:F, and ZnO-SnO2:F and CdO-SnO2:F interfaces. Oxygen 1s absorption spectra, which relate to the O 2p partial density of states of the conduction band, indicate that the interface is associated with a reduction in Ti d-O p orbital hybridization and an alteration of the TiO2 crystal field. These observations are consistent with measured titanium 2p absorption spectra, which in addition provide evidence for distortion of long-range order around the cation site in the interfacial TiO2. The TiO2-SnO2:F interface is a functional component of a number of optoelectronic devices, perhaps most notably within the anode structure of solar cell architectures. In nonequilibrium conditions, such as those found in operating solar cells, interfacial electronic structure directly influences performance by modifying, for instance, the quasi-Fermi level electrons and the potential distribution at the transparent electrode.

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Research on a Poly-Generation System for Gas-Biochar-Heat-Electricity by Supercritical Water Gasification of Biomass Waste

SSRN

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SSRN 2024年

作者： Wang, Cui Jin, Hui School of Water and Environment Chang'an University Xi’an710054 China Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of the Ministry of Education Chang'an University Xi’an710054 China Key Laboratory of Eco-hydrology and Water Security in Arid and Semi-arid Regions of Ministry of Water Resources Chang’an University Xi’an710054 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China Ministry of Education of China Chongqing University Chongqing400044 China

Biomass energy is renewable and rich in the world, providing a solution for the shortage in fossil fuel and serious environmental pollution. Proposing efficient utilization method of biomass waste demands urgent attention. Supercritical water gasification (SCWG) process is a potential technology. In this work, a poly-generation system based on SCWG was developed to convert biomass waste to gas, biochar, heat and electricity. Firstly, mass, energy, and exergy flow were calculated at the typical condition. Subsequently, impact of various operating parameters, including gasification temperature, mass flowrate of preheated water, biomass concentration, on the hydrogen-rich syngas yield, generated electricity, thermodynamic performance of the system was investigated. The result demonstrated that the exergy loss primarily occurred on cooler, reactor, heat exchanger and preheater, accounting for more than 90% of total exergy loss under different conditions, arising from irreversible reaction, heat transfer and heat dissipation. Higher temperature, higher biomass concentration and more preheated water exerted a positive effect for hydrogen-rich gas production and supplied heat energy, while these parameters were disadvantageous to exergy efficiency. Biochar energy was primarily affected by biomass concentration. Energy efficiency increased with preheated water quantity and biomass concentration rising, and impact of biomass concentration was more significant. Conversely, evaluated gasification temperature displayed an adverse effect on energy efficiency. The maximal exergy efficiency reached about 58.3% at 550°C, biomass concentration of 33%, preheated water mass flowrate of 900 kg·h-1 © 2024, The Authors. All rights reserved.

关键词： Biomass

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Corrigendum to ‘Experimental investigation of the microlayer and dry spot dynamic characteristics in a small channel flow boiling by laser interferometry method’ [International Journal of Heat and Mass Transfer 201 (2023) 123585]

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International Journal of Heat and Mass Transfer 2023年 209卷

作者： Zhong-Xiang Shen Ming Gao Wu-han Dong Li-xin Zhang Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai 200093 China

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Experimental study on steam plume and temperature distribution for sonic steam jet

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Journal of Physics: Conference Series 2009年第1期147卷

作者： Xinzhuang Wu Junjie Yan Wenjun Li Dongdong Pan Ying Li State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 P.R.China

The sonic steam jet in subcooled water was investigated experimentally over a wide range of steam mass flux and water temperature conditions. Four different steam plume shapes were observed in present test conditions, and the condensation form was mainly controlled by the steam mass flux and water temperature. Moreover, the unstable jet was observed on the condition of low steam mass flux and high water temperature. The transition criterion of unstable-stable jet was also given. The temperature fields in the steam plume and in the surrounding water were measured. Axial temperature distributions represented the four typical steam plumes, and the fluctuation of axial temperature confirmed the existence of expansion and compression waves. Additionally, the radial temperature distributions were independent of water temperature for small radial distance at nozzle exit, and further the axial location was apart from the nozzle exit, longer the radial distance affected by the momentum diffusion.

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An efficient cellular flow model for cohesive particle flocculation in turbulence

arXiv

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arXiv 2020年

作者： Zhao, K. Vowinckel, Bernhard Hsu, T.-J. Köllner, T. Bai, B. Meiburg, E. Department of Mechanical Engineering UC Santa Barbara CA93106 United States State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Leichtweiß-Institut für Wasserbau Technische Universität Braunschweig Braunschweig38106 Germany Center for Applied Coastal Research Department of Civil & Environmental Engineering University of Delaware NewarkDE19716 United States

We propose a one-way coupled model that tracks individual primary particles in a conceptually simple cellular flow setup to predict flocculation in turbulence. This computationally efficient model accounts for Stokes drag, lubrication, cohesive and direct contact forces on the primary spherical particles, and allows for a systematic simulation campaign that yields the transient mean floc size as a function of the governing dimensionless parameters. The simulations reproduce the growth of the cohesive flocs with time, and the emergence of a log-normal equilibrium distribution governed by the balance of aggregation and breakage. Flocculation proceeds most rapidly when the Stokes number of the primary particles is O(1). Results from this simple computational model are consistent with experimental observations, thus allowing us to propose a new analytical flocculation model that yields improved agreement with experimental data, especially during the transient stages. Copyright © 2020, The Authors. All rights reserved.

关键词： Turbulence

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A Piv Measurement and Numerical Simulation of Gas‐Liquid Two‐Phrase flow in An Aeration Tank

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AIP Conference Proceedings 2007年第1期914卷 453-457页

作者： Wen Cheng Chun‐Di Yang Yuichi Murai Fujio Yamamoto 1State Key Laboratory of Multiphase Flow in Power Engineerig Xi’ann Jiaotong University Xi’an 710049 China 2Environment Research Institute Xian University of Technology Xian 710048 China 3Div. of Mec. Science Graduate School of Engineering Hokkaido University Japan 4Graduate School of Engineering University of Fukui Bunkyo 3‐9‐1 Fukui 910‐8507 Japan

Aeration plays an important role in the treatment of activated sludge. The aeration performance is deeply affected by the movement law of bubble liquid flow in aeration tank. In order to discuss the influence of gas‐phase, liquid‐phase motions in an aeration tank on the sewage disposal, three kinds of boundaries and initial conditions were applied in the experiment to study the law of two‐phase flow. A developed two‐equation turbulence model was employed in this paper. Results obtained by experiment are compared with those from the mathematical model. It is found that the results of measurement and simulation agree with each other.

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Fluoride-Salt-Cooled High-Temperature Reactor: An Integrated Nuclear-Based Energy Production and Conversion System

SSRN

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SSRN 2023年

作者： Zhang, Dalin Li, Xinyu Jiang, Dianqiang Zhou, Xingguang Lv, Xindi Yun, Shichang Wu, Wenqiang He, Xuanang Li, Haoyang Min, Xin Chen, Kailong Tian, Wenxi Qiu, Suizheng Su, Guanghui Zhao, Quanbin Fu, Yao Tang, Chuntao Zhuo, Wenbin Li, Jinggang Zuo, Jiaxu State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai201800 China Shanghai Nuclear Engineering Research & Design Institute Co. Ltd. Shanghai200233 China CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology Nuclear Power Institute of China Chengdu610213 China China Nuclear Power Technology Research Institute Guangdong Shenzhen518000 China Nuclear and Radiation Safety Center Ministry of Ecology and Environment Beijing100082 China

Based on the analysis of energy structure and the development trends of advanced nuclear energy technology, combining the complementary advantages of nuclear energy and other energy sources in China, the Fluoride-salt-cooled High-temperature Reactor(FuSTAR) system has been proposed. FuSTAR system is designed to address production capacity issues in areas with energy shortages or resource concentration and can be combined with high-temperature process heat to achieve high-value-added processes such as hydrogen production. In this paper, the design and optimization processes of FuSTAR are described from three aspects: the neutronic and thermal-hydraulic system, the thermal transport system, and the power cycle system. Tri-structural isotropic fuel combined with helical cruciform elements has been studied in detail on the neutron physics and thermal-hydraulic properties, and the flow and heat transfer experiment is carried out for the first time. The multilayer nonlinear programming method has been applied to the design of thermal transport systems and the passive residual heat removal system and proved to be fast and efficient. Then the optimal parameters and configuration of the thermoelectric conversion system are obtained directly by using the superstructure optimization method, which saves computing resources greatly. Based on the above design and parameters, the inherent safety of FuSTAR is demonstrated through deterministic safety analysis. In addition, the iodine-sulfur cycle technology is also designed and analyzed, and the characteristics of tritium production in FuSTAR are calculated. The research provides important guidance for the detailed design and operation of FuSTAR. Moreover, this study highlights the significant potential of integrating nuclear energy with other energy sources in an optimized energy-production system. Based on the current research findings, prospects for future research directions are also suggested. © 2023, The Authors. All rights r

关键词： High temperature reactors

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Flocculation of suspended cohesive particles in homogeneous isotropic turbulence

arXiv

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arXiv 2021年

作者： Zhao, K. Pomes, F. Vowinckel, Bernhard Hsu, T.-J. Bai, B. Meiburg, E. Department of Mechanical Engineering UC Santa Barbara Santa BarbaraCA93106 United States State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Leichtweiß-Institute for Hydraulic Engineering and Water Resources Technische Universität Braunschweig Braunschweig38106 Germany Center for Applied Coastal Research Department of Civil & Environmental Engineering University of Delaware NewarkDE19716 United States

We investigate the dynamics of cohesive particles in homogeneous isotropic turbulence, based on one-way coupled simulations that include Stokes drag, lubrication, cohesive and direct contact forces. We observe a transient flocculation phase characterized by a growing average floc size, followed by a statistically steady equilibrium phase. We analyze the temporal evolution of floc size and shape due to aggregation, breakage, and deformation. Larger turbulent shear and weaker cohesive forces yield elongated flocs that are smaller in size. Flocculation proceeds most rapidly when the fluid and particle time scales are balanced and a suitably defined Stokes number is O(1). During the transient stage, cohesive forces of intermediate strength produce flocs of the largest size, as they are strong enough to cause aggregation, but not so strong as to pull the floc into a compact shape. Small Stokes numbers and weak turbulence delay the onset of the equilibrium stage. During equilibrium, stronger cohesive forces yield flocs of larger size. The equilibrium floc size distribution exhibits a preferred size that depends on the cohesive number. We observe that flocs are generally elongated by turbulent stresses before breakage. Flocs of size close to the Kolmogorov length scale preferentially align themselves with the intermediate strain direction and the vorticity vector. Flocs of smaller size tend to align themselves with the extensional strain direction. More generally, flocs are aligned with the strongest Lagrangian stretching direction. The Kolmogorov scale is seen to limit floc growth. We propose a new flocculation model with a variable fractal dimension that predicts the temporal evolution of the floc size and shape. © 2021, CC BY.

关键词： Flocculation

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Determination of mass diffusion coefficients of oxygenated fuel additives in air using digital real-time holographic interferometry

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Journal of Physics: Conference Series 2009年第1期147卷

作者： Maogang He Ying Guo Qiu Zhong Ying Zhang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 People's Republic of China

In this work, an experimental system based on digital real-time holographic interferometry for measuring the mass diffusion coefficients of fluid is introduced. The method of processing interference fringe hologram is also introduced thoroughly. By uncertainties analysis and experimental verification, the accuracy of this system is validated. The experimental uncertainties in temperature and mass diffusion coefficient are estimated to be no greater than ± 0.16 K and ± 0.2 %, respectively. On this basis, the mass diffusion coefficients of three fuel additives, diethyl 1,6-hexanedioate (diethyl adipate, DEA), dimethyl carbonate (DMC) and diethyl carbonate (DEC) in air were measured at T = (278.15 to 338.15) K under atmospheric pressure, and polynomial was fitted by the experimental data.

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Realization of Multilocal Gradient-Doping Pcn by Alkali Metal Ion Sustained Release Capsules for Enhanced Photocatalytic Water Splitting

SSRN

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SSRN 2023年

作者： Yan, Jiawei Fang, Fenjian Wei, Zhidong Chi, Jiasheng Chen, Mingxia Jiang, Zhi Jiang, Kun Shen, Shaohua Shangguan, Wenfeng Research Center for Combustion and Environment Technology Shanghai Jiao Tong University Shanghai200240 China College of Smart Energy Shanghai Jiao Tong University Shanghai200240 China College of Electrical Energy and Power Engineering Institute of Fuel Cells Shanghai Jiao Tong University Shanghai200240 China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China

The gradient-doping technique has been widely applied to induce an oriented built-in electric-field. However, it is still not efficient enough for charge mobility especially for particulate semiconductors, as the field is primarily in one direction from inner to surface. Here, we propose a multilocal gradient-doping technique that a nano-capsule is designed to store dopants and then release them into semiconductors nonuniformly. As an illustration, scattered pyrochlore-type K2Ta2O6 nanoparticles have been validated the capability of storing and releasing K+, which subsequently diffuse into the substrate PCN. Multi point-radiative gradient in K+ concentration, confined within the K2Ta2O6’s vicinity, will construct several 3D potential wells which can not only accelerate the carrier separation but also offer more migration channels for both photo-induced electrons and holes to the surface. Consequently, the multilocal K+ gradient-doping PCN shows the longest carriers’ lifetime and highest AQY (~21.8% at 400 nm) compared with the other uniformly doping techniques. © 2023, The Authors. All rights reserved.

关键词： Charge transfer

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