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NUMERICAL SIMULATION AND COMPARISON OF WATER INTAKE-OUTLET METHODS IN power PLANTS

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Journal of Hydrodynamics 2007年第5期19卷 623-629页

作者： CHENG You-liang YING Bo-fen school of energy and power engineering North China Electric Power University Baoding 071003 China

The eclipsed form arrangement and march-past method of water intake-outlet arrangements in power plants were researched by 3-D numerical simulation based on the k-e two-equation turbulence model. Firstly, the flowing characteristics of eclipsed form arrangement were analyzed and the effects of some main factors on inlet temperature were investigated. The simulation results are basically in agreement with those of the previous experiments. Then, by comparing the inlet temperature of the above two intake-outlet methods, the superiority and its existent conditions of the eclipsed form were examined.

关键词： method water simulation eclipsed form arrangement,intake-outlet inlet temperature,march-past numerical

An exploration for the macroscopic physical meaning of entropy

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Science china(Technological Sciences) 2010年第7期53卷 1809-1816页

作者： WU Jing1 & GUO ZengYuan2 1 College of energy and power engineering, Nanjing university of Aeronautics and Astronautics, Nanjing 210016, china 2 Key Laboratory for Thermal Science and power engineering of Ministry of Education, school of Aerospace, Tsinghua university, beijing 100084, china 1. College of energy and power engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China2. Key Laboratory for Thermal Science and Power Engineering of Ministry of Education School of Aerospace Tsinghua University Beijing 100084 China

The macroscopic physical meaning of entropy is analyzed based on the exergy (availability) of a combined system (a closed system and its environment), which is the maximum amount of useful work obtainable from the system and the environment as the system is brought into equilibrium with the environment. The process the system experiences can be divided in two sequent sub-processes, the process at constant volume, which represents the heat interaction of the system with the environment, and the adiabatic process, which represents the work interaction of the system with the environment. It is shown that the macroscopic physical meaning of entropy is a measure of the unavailable energy of a closed system for doing useful work through heat interaction. This statement is more precise than those reported in prior literature. The unavailability function of a closed system can be defined as T0S and p0V in volume constant process and adiabatic process, respectively. Their changes, that is, AiTgS) and A (p0V) represent the unusable parts of the internal energy of a closed system for doing useful work in corresponding processes. Finally, the relation between Clausius entropy and Boltzmann entropy is discussed based on the comparison of their expressions for absolute entropy.

关键词： entropy macroscopic physical meaning exergy heat interaction

The CAD System Development for power Plants Pipe-Prefabrication

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武汉理工大学学报 2006年第S2期28卷 718-723页

作者： RUI Xiaoming~1 MA Zhiyong~2 1.Laboratory of Condition Monitoring and Control for power Plant Equipment, 2.school of energyand power engineering,north china electric power university,beijing 102206,china Laboratory of Condition Monitoring and Control for power Plant Equipment school of energyand power engineering North China Electric Power UniversityBeijing 102206China

An intelligent design software system for the power station pipe-prefabrication (PPDS) has been developed in the paper,which is taking pipe material database as core and developed on the platform of AutoCAD and Borland C++. Whereas design and construction of power plants in china belong to different deportments,the input and recognition problem of pipeline system disposition chart must be solved firstly for the prefabrication *** on AI technology,the model fast building subsystem (MFBS) was established for entering the 3-D pipeline graph data,so that the problems of reconstruction of pipeline digital model and computer identification of original 2-D design data can be solved. The optimization design scheme in the pipe-prefabrication process has been studied and also the corresponding algorithm put *** technique and system mentioned can effectively raise the pipe-prefabrication design quality and efficiency in the con- struction of large scale power plants,reduce the period of design and the waste of raw *** has still offered the functions such as the construction design for pipeline prefabricated process,the detailing drawing for manufacturing pipe section and automatic generating the technical files for the completed project.

关键词： computer aided design pipe-prefabrication design power plants building engineering

CFD simulation of pressure fluctuation characteristics in the gas-solid fluidized bed:Comparisons with experiments

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Petroleum Science 2011年第2期8卷 211-218页

作者： Wang Qingcheng Zhang Kai Gu Hongyan beijing Shenwu Thermal energy Technology Co. LTD Beijing 102200 China State Key Laboratory of Heavy Oil Processing China University of Petroleum Beijing 102249 China National engineering Lab for Biomass power Generation Equipment North China Electric Power University Beijing 102206 China electrical engineering College Guizhou University Guiyang 550025 China

A simple hydrodynamic model based on two-fluid theory, taking into account the effect of discrete particles on both the gas- and solid-phase momentum equations, was used to numerically investigate the pressure fluctuation characteristics in a gas-solid fluidized bed with the aid of CFX 4.4, a commercial CFD software package, by adding user-defined Fortran subroutines. Numerical simulations together with typical experimental measurements show that pressure fluctuations originate above the distributor when a gas pulse is injected into the fluidized bed. The pressure above the bubble gradually increases due to the presence of a rising bubble. When the bubble passes through the bed surface, the pressure near the bed surface gradually decreases to a lower value. Moreover, the pressure signals in the bubbling fluidized beds show obviously periodic characteristics. The major frequency of pressure fluctuations at the same vertical position is affected slightly by the operating gas velocity, and the amplitude of pressure fluctuations is related to both the operating gas velocity and the vertical height. In this study, the influence of the operating gas velocity on the pressure wave propagation velocity can be ignored, and only two peak frequencies in the power spectrum of the pressure fluctuations are observed which are associated with the bubble formation above the distributor and its eruption at the bed surface.

关键词： Gas-solid fluidized bed CFD simulation experimental measurements propagation ofpressure fluctuations pressure wave velocity pressure fluctuation frequency

Synchronization of Digital Chaos in Secure Communication Systems

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Journal of university of Science and Technology beijing 2001年第4期8卷 299-305页

作者： Geng Zhao, Deling Zheng, ShaojunHuang 1)College of electric Science and Technology beijing. beijing 100070, china 2)Information engineering school, university of Science and Technology beijing. beijing 100083, china Coll Elect Sci & Technol beijing Beijing 100070 Peoples R China Univ Sci & Technol beijing Informat Engn Sch Beijing 100083 Peoples R China

The theories of synchronization based on secure communications using digital chaos are presented. A new synchronous method-cycles-interval Pulse drive is developed and realized. Experimental results show it is available, and in order to reduce synchronous noise, a method using model references solves the ratio of signal power to noise power, so the secure communication system can be realized.

关键词： digital chaotic synchronization cycles-interval pulses drive synchronous noise model reference

Preparation of semi-solid AlSi7Mg alloy slurry with big capability

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Rare Metals 2010年第6期29卷 642-645页

作者： LI Sha and MAO Weimin school of Materials Science and engineering,university of Science and Technology beijing,beijing 100083,china school of Materials Science and engineering University of Science and Technology Beijing Beijing China

Semi-solid AlSi7Mg alloy slurry was prepared by low superheat pouring and weak traveling-wave electromagnetic *** effects of pouring temperature and stirring power on the microstructure of AlSi7Mg alloy slurry were *** results show that the semi-solid AlSi7Mg alloy slurry of 5 kg can be *** new technology can save energy and make the pouring process *** the pouring temperature is decreased at a stirring power of 0.41 kW,the shape of primary α-Al grains gradually changes from dendritic-like to *** the alloy melt is poured at the temperature（630°C） with a certain superheat,the pouring process becomes easier,and the spherical microstructure of AlSi7Mg alloy slurry can be prepared by the weak traveling-wave electromagnetic *** the pouring temperature is 630°C,increasing the stirring power appropriately can result in better spherical primary α-Al grains,but if the stirring power is increased to a certain value（1.72 kW）,the shape of primary α-Al grains does not obviously improve when the stirring power is continually increased.

关键词： aluminum alloys metal forming semisolid slurry electromagnetic stirring microstructure

Analysis on Fast Reclosing of Line Start Permanent Magnet Motor with Time-Stepping Finite Element Method

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Analysis on Fast Reclosing of Line Start Permanent Magnet Mo...

Experimental study on drying of typical MSW under incinerator-like conditions

11th International Conference on electrical Machines and Systems

作者： Luo Yingli Li Zhiqiang Liu Mingji Zhu Lifang school of electrical and Electronic engineering north china electric power university beijing 102206 china. school of electrical and Electronic engineering North China Electric Power University Beijing China

＜正＞The transient process of fast reclosing of line start permanent magnet synchronous motor was analyzed by time-stepping finite element *** shows that reciosure could bring serious danger on permanent magnet motor... 详细信息

ISBN: (纸本)9787506292214

关键词： Magnetic analysis Permanent magnet motors Finite element methods Nonlinear equations Rotors Torque Voltage Coupling circuits Electromagnetic coupling Magnetic fields

来源： cnki会议评论

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Science china(Technological Sciences) 2007年第5期50卷 636-643页

作者： ZHANG YanGuo1, CHEN MeiQian2, MENG AiHong1, LI QingHai1 & CHEN YunXuan2 1 Key Laboratory for Thermal Science and power engineering of Ministry of Education, Tsinghua university, beijing 100084, china 2 school of Mechanical, Electronical and Control engineering, beijing Jiaotong university, beijing 100044, china 1. Key Laboratory for Thermal Science and power engineering of Ministry of Education Tsinghua University Beijing 100084 China 2. school of Mechanical Electronical and Control Engineering Beijing Jiaotong University Beijing 100044 China

In this paper, a series of experiments were conducted to investigate the drying of typical municipal solid wastes (MSW) in a muffle incinerator. From the experimental drying characteristic curves, the effects of temperature on drying process were observed to be more obvious in the low temperature region than in the high tem- perature region in muffle incinerator. At a specified drying temperature, drying time was highly dependent upon the packed waste thickness, having an exponent rela- tion with the thickness. When the drying temperature increased or the thickness of potato bulks was diminished, the maximum drying rate reduced. Based on the first-order reaction, activation energy (Ea), and factor A of potato and cabbage were determined.

关键词： drying, MSW, potato blocks, cabbage stems, temperature, dying rate

A Win-win Strategy for Risk Decision-making under a BOT Scheme

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A Win-win Strategy for Risk Decision-making under a BOT Sche...