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Silver-Doping Induced Lattice Distortion in TiO2 Nanoparticles

Chinese Physics Letters 2009年第7期26卷 339-342页

作者：吴雪炜吴大建刘晓峻 Department of Electronic Science and Engineering Key Lab of Modern Acoustics of MOE Nanjing University Nanjing 210093 State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong University Xi'an 710049

The Ag-doping effects on Ti02 nanoparticles are investigated by means of x-ray diffraction （XRD） and Raman scattering spectroscopy. XRD and Raman results indicate that Ag-doping stabilizes the rutile phase in TiO2. We find an Ag-doping induced lattice expansion in both anatase and rutile phases. The Ag-doping has different influences on the lattice distortion for anatase and rutile phases, that is, the e/a-value for the anatase phase decreases with 0.5% Ag-doping and then increases with 1~ Ag-doping while that for the rutile phase shows a gradual increase with increasing Ag-doping. We have ascribed the different variations of lattice distortion due to Ag-doping to the change of interracial interaction between the anatase and rutile phases induced by different Ag concentrations.

关键词： PHOTOCATALYTIC ACTIVITY VISIBLE-LIGHT AG-TIO2 ANATASE RUTILE FILMS AG

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Granular surface flow in a two-dimensional rotating drum: Particle dynamics simulation

Granular surface flow in a two-dimensional rotating drum: Pa...

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2006 AIChE Spring National Meeting - 5th World Congress on Particle Technology

作者： Li, S.-Q. Zhang, X. Zhao, X.-L. Yao, Q. Key Lab. of Power Engineering and Thermal Science Department of Thermal Engineering Tsinghua University Beijing 100084 China

Granular surface flows in partially-filled rotating drums are widely encountered in many industrial applications, for example incineration, calcination, granulation, etc., but the understanding of such flows is still less clear than those of fluid flow. In this paper, The particle dynamics (PD) simulation, derived from molecular dynamics simulation, has been performed in a two-dimensional horizontal drum, whose axial length is only 35 times of particle diameters to delete the effect of the inside wall. The PD simulation is validated by the experimental data using method of positron emission particle tracking in literature. Simulated results indicate that the behavior of granular flow in rotating drums can be classified into two distinct zones: the shear active layer at bed surface and the quasi-static plug flow region adjacent to wall. It is noted that the behavior of granular solids in plug flow region is not a simple rigid rotation at an angular wall velocity. It implies that there exists a plastic deformation of granular material in this region. A continuum approach is developed for this phenomenon, in which the plastic flow in plug-flow region is originally described by using an exponential function and the cascading flow in active layer is described by a linear profile of shear flow.

关键词： Granular materials

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Systematic characterization of transport and thermoelectric properties of a macroscopic graphene fiber

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Nano Research 2016年第11期9卷 3536-3546页

作者： Weigang Ma Yingjun Liu Shen Yan Tingting Miao Shaoyi Shi Mincheng Yang Xing Zhang Chao Gao Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering Mechanics Tsinghua University Beijing 100084 China MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and Engineering Key Laboratory of Adsorption and Separation Materials & Technologies of Zhejiang Province Zhejiang University Hangzhou 310027 China Department of Thermal Engineering Tsinghua University Beijing 100084 China Key Laboratory of Process Fluid Filtration and Separation College of Mechanical and Transportation Engineering China University ot Petroleum Beijing Beijing 102249 China

Graphene, a two-dimensional material with extraordinary electrical, thermal, and elastic performance, is a potential candidate for future technologies. However, the superior properties of graphene have not yet been realized for graphenederived macroscopic structures such as graphene fibers. In this study, we systematically investigated the temperature （T ）-dependent transport and thermoelectric properties of graphene fiber, including the thermal conductivity （A）, electrical conductivity （o）, and Seebeck coefficient （S）. A increases from 45.8 to 149.7 W·m^-1·K^-1 and then decreases as T increases from 80 to 290 K, indicating the boundary-scattering and three-phonon Umklapp scattering processes. σ increases with T from 7.1 × 10^4 to 1.18 × 10^5 S·m^-1, which can be best explained by the hopping mechanism. S ranges from -3.9 to 0.8 μV·K^-1 and undergoes a sign transition at approximately 100 K.

关键词： macroscopic graphene fiber thermoelectric properties thermal conductivity electrical conductivity Seebeck coefficient

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Corrosion behavior and mechanism of heat-resistant steel T91 in high-temperature carbon dioxide environment

Corrosion behavior and mechanism of heat-resistant steel T91...

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Chinese Materials Conference, 2018

作者： Gui, Yong Liang, Zhiyuan Yu, Miao Zhao, Qinxin Key Laboratory of Thermal Fluid Science and Engineering of MOE School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China

ISBN: (纸本)9783035713848

Corrosion behavior of martensitic heat resisting steel T91 in high-temperature carbon dioxide environment at 500-700 °C was investigated. X-ray diffraction, scanning electron microscopy and glow-discharge optical emission spectrometry were employed to characterize the corrosion products. The results showed that the corrosion kinetics of T91 followed a parabolic law with experimental time. The oxide scale thickness of T91 followed an exponential growth law from 500 °C to 700 °C. Internal carburization was detected underneath the corrosion scale. What’s more, the carburization depth was larger than the corrosion scale. The variations of Cr and C elements distribution were discussed. © 2019 Trans Tech Publications, Switzerland.

关键词： Carbon dioxide

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Transient flow and thermal performance of integrated deflector under periodic supersonic flame impingement 15

Transient flow and thermal performance of integrated deflect...

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15th International Heat Transfer Conference, IHTC 2014

作者： Zhang, J.J. Qu, Z.G. Fu, R.P. He, Y.L. MOE Key Laboratory of Thermal Fluid Science and Engineering School of Energy and Power Engineering Xi'An Jiaotong University Xi'an Shaanxi710049 China

Flow deflector is an effective approach to realize the thermal spreading and flow splitting of high temperature gas from jet impingement. Two integrated deflectors composed of ablation-resistant layer, thermal insulation layer and multifunctional lattice metal layer are designed and prepared. The transient thermal performance of deflectors under periodical supersonic flame impingement is experimentally studied by employing a kerosene flame jet. A verified 3D numerical model is established to analyze the effects of jet distance, horizontal angel and axial angel of deflector on the flow and thermal distribution characteristics. The experimental results show that the temperature variation of impinged surface with impingement periods trends to stable periodic fluctuation after four periods. Compared to carbon aerogel, the phase change material of LiF as the Layer-2 of deflector decreases the whole temperature level of deflector and especially reduces ablation rate of C/SiC plate by about 40%. The numerical simulation finds that the deflector behaves a good fluid deviating capacity towards the given direction (more than 50% gas flow towards the up section). The gas accelerating effect above the impingement position forms a small region with second peak pressure, temperature and heat transfer coefficient. The increase of horizontal angle or the decrease of axial angle enlarges the highest pressure and temperature on impinged surface due to the more uniform gas distributions deviated by deflector.

关键词： Flow of gases

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A Hierarchical Multi-stage Fusion Deep Learning Framework for Short-Term Wind power Prediction

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Renewable Energy 2025年

作者： Rui Qin Hwa Kian Chai Kai Liu Hang Yu Jing Huang National Key Lab of Aerospace Power System and Plasma Technology Xi’an Jiaotong University Xi’an 710049 P.R. China Institute for Infrastructure and Environment School of Engineering The University of Edinburgh EH9 3FB Edinburgh UK Department of Industrial Engineering University of Padua Padova 35131 Italy Key Laboratory of Thermal-Fluid Science and Engineering MOE School of Energy and Power Engineering Xi’an Jiaotong University 710049 Xi’an P.R. China

The Supervisory Control and Data Acquisition (SCADA) system encompasses a wealth of information with diverse physical significance, which can be categorized into homogeneous and heterogeneous data. The underlying differences and complementarities within and among these data types are crucial for enhancing the performance of short-term wind power forecasting. Accordingly, this paper introduces a deep learning architecture with a multi-stage information fusion mechanism for short-term wind power forecasting. The initial fusion module focuses on analyzing the internal correlations of homogeneous information and extracting valuable insights from historical data. Subsequently, the second fusion module emphasizes the disparities among heterogeneous information, highlighting the interplay and mutual enhancement of different physical data through spatial and temporal interaction mechanisms. This multi-layered, multi-dimensional information fusion strategy not only bolsters the model's ability to comprehend intrinsic data relationships but also enhances forecasting accuracy. Ultimately, a bidirectional long short-term memory network is employed for real-time and precise wind power forecasting tasks. Three experiments conducted on real SCADA data from wind farms substantiate the reliability and effectiveness of the proposed method. The approach outperforms 12 existing advanced methods in both single-step and multi-step predictions, significantly improving the accuracy of short-term wind power forecasting and providing robust decision support for wind farm operations and maintenance.

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A PID controller with desired closed-loop time response and stability margin 36

A PID controller with desired closed-loop time response and ...

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第36届中国控制会议

作者： Xinxin Wang Xiaoqiang Yan Donghai Li School of mechanical engineering university of science and technology Beijing State Key Lab of Power Systems Department of Thermal Engineering Tsinghua University

ISBN: (纸本)9781538629185

In this article, we propose a PID tuning method which can simultaneously guarantee desired closed-loop time response and stability margin. For systems without time-delay, dominant pole placement method is used to guarantee the desired closed-loop time response and generalized-frequency method is adopted to give systems the desired stability margin. For systems with time-delay, however, the desired closed-loop time response and the stability margin are obtained through dominant pole placement method and gain-phase margin test method respectively. To demonstrate the effectiveness and confirm the validity of the proposed methodology, examples are provided for illustration.

关键词： PID controller the desired closed-loop time response stability margin

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Crossover Equation of State for Selected Hydrocarbons(C4–C7)

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Chinese Journal of Chemical engineering 2014年第Z1期22卷 1291-1297页

作者：申爱景刘强段远源杨震 Key Laboratory of Thermal Science and Power Engineering of MOE Beijing Key Laboratory for CO2Utilization and Reduction Technology Tsinghua University

The organic Rankine cycle(ORC) has attracted attention for waste heat recovery and renewable energy *** accurate prediction for thermodynamic properties of working fluids is of great importance for cycle performance evaluations and system design. Particularly, hydrocarbons are promising for their good performance and low global warming potentials. Moreover, the thermal efficiency of the ORC is higher when the evaporation temperature is closer to the critical temperature, which makes the properties in the critical region rather important. Recent research has shown that using mixture as working fluid can achieve better temperature matches. Therefore, an equation of state(Eo S) that can be extended to mixture calculations is more attractive. Specific Eo S for selected hydrocarbons is precise, but very complex. Cubic Eo Ss, such as widely used Peng–Robinson Eo S and Soave–Redlich–Kwong(SRK) Eo S, fail to accurately predict liquid densities over wide pressure ranges or pressure–density–temperature(pρT) properties in the near-critical region. This work combines the volume translation approach and the crossover method to provide better prediction for thermodynamic properties in the critical region and in regions far from the critical point. A crossover volume translation SRK Eo S is developed and used for n-butane, i-butane, n-pentane, i-pentane, n-hexane, i-hexane and n-heptane. The volume translation term is set as a constant to ensure the accuracy of the saturated liquid density at low reduced temperatures. Then, the crossover method is introduced into the volume translation Eo S to improve the predictions of thermodynamic properties in the critical region. Six crossover parameters are used, which are constants or functions of acentric factor and critical parameters. Therefore, none of the parameters in the crossover volume translation SRK Eo S is adjustable, which makes the crossover Eo S totally predictive and easily extend to mixtures. Comparisons show that th

关键词： Hydrocarbon Organic Rankine cycle Thermodynamic property Crossover Volume translation SRK Eo S

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Evolution of nanofluid rayleigh-bénard flows between two parallel plates: A mesoscopic modeling study

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Journal of Nanotechnology in engineering and Medicine 2013年第4期4卷 040905页

作者： Lu, Gui Duan, Yuan-Yuan Wang, Xiao-Dong Key Laboratory for Thermal Science and Power Engineering MOE Tsinghua University Beijing 100084 China Institute of Thermal Engineering Beijing Jiaotong University Beijing 100044 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

The developing and developed nanofluid Rayleigh-Bénard flows between two parallel plates was simulated using the mesoscopic thermal lattice-Boltzmann method (LBM). The coupled effects of the thermal conductivity and the dynamic viscosity on the evolution of Rayleigh-Bénard flows were examined using different particle volume fractions (1-4%), while the individual effects of the thermal conductivity and the dynamic viscosity were tested using various particle sizes (11 nm, 20 nm, and 30 nm) and nanoparticle types (Al 2O3, Cu, and CuO2). Two different heating modes were also considered. The results show that Rayleigh-Bénard cell in nanofluids is significantly different from that in pure fluids. The stable convection cells in nanofluids come from the expansion and shedding of an initial vortex pair, while the flow begins suddenly in pure water when the Rayleigh number reaches a critical value. Therefore, the average Nusselt number increases gradually for nanofluids but sharply for pure liquids. Uniform fully developed flow cells with fewer but larger vortex pairs are generated with the bottom heating with nanofluids than with pure liquid, with extremely tiny vortexes confined near the top heating plate for top heating. The number of vortex pairs decreases with increasing nanoparticle volume fraction and particle diameter due to the increasing of dynamic viscosity. The average Nusselt number increases with the increasing Rayleigh number, while decreases with the increasing nanoparticle diameters. The nanoparticle types have little effect on the Rayleigh-Bénard flow patterns. The Rayleigh-Bénard flows are more sensitive with the dynamic viscosity than the thermal conductivity of nanofluids. Copyright © 2013 by ASME.

关键词： Nanoparticles

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Catalytic urea hydrolysis by composite metal oxide catalyst towards efficient urea-based SCR process:performance evaluation and mechanism investigation

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Frontiers of Environmental science & engineering 2023年第5期17卷 67-80页

作者： Yuchen Li Zhen Chen Xiangyu Zhang Kun Yang Lidong Wang Junhua Li MOE Key Laboratory of Resources and Environmental Systems Optimization Department of Environmental Science and EngineeringNorth China Electric Power UniversityBeijing 102206China State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China Xi’an Thermal Power Research Institute Co. Xi’an 710032China

As a promising option to provide gaseous NH_(3) for SCR system,catalytic urea hydrolysis has aroused great attention,and improving surface area and activity of catalysis are the crucial issues to be solved for efficient urea ***,a composite metal oxide(TiO_(2)@Al_(2)O_(3))catalyst was prepared by a simple hydrothermal method,with mesoporous alumina(γ-Al_(2)O_(3))as *** results verify the mesoporous structure and submicron cluster of TiO_(2)@Al_(2)O_(3),with exposed crystal faces of(101)and(400)for TiO_(2)andγ-Al_(2)O_(3),*** electronegativity difference of Ti4+and Al3+changes the charge distribution scheme around the interface,which provides abundant acid/base sites to boost the urea ***,for an optimal proportioning with nano TiO_(2)content at 10 wt.%,the hydrolysis efficiency can reach up to 35.2%at 100℃ in 2 h,increasing by~7.1%than that of the blank experiment.^(13)C NMR spectrum measurements provide the impossible intermediate species during urea *** calculations are performed to clarify the efficient H_(2)O decomposition at the interface of TiO_(2)@Al_(2)O_(3).The result offers a favorable technology for energy-efficiency urea hydrolysis.

关键词： SCR Urea hydrolysis Catalytic Water dissociation Electronegativity

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