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Secondary side flow field of steam generator with coupled heat transfer from primary to secondary side fluid

Yuanzineng Kexue Jishu/Atomic Energy Science and Technology 2014年第8期48卷 1398-1405页

作者： Cong, Teng-Long Tian, Wen-Xi Qiu, Sui-Zheng Su, Guang-Hui Department of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

The 3D flow characteristics in SG can provide input for the analysis of flow induced vibration (FIV). The secondary side flow field was simulated based on the porous media model with FLUENT solver. The flow resistances of flow along and cross tubes as well as flow resistances of downcomer, support plates and separators were added to the momentum equation. The 3D heat transfer from primary to secondary side fluid was calculated during iteration and set as the energy source of secondary side fluid, and the calculation results agree well with the design values. Meanwhile, the results show that the resultant localized thermal-hydraulic characteristics were unevenly distributed. The maximum and minimum flow vapor qualities flowing into the primary separators are 0.75 and 0.07, respectively. The average heat transfer coefficients of primary and secondary sides are 15 856.5 and 63 623.0 W/(m2·K), respectively. The maximum heat transfer coefficient of secondary side is 122 862.9 W/(m2·K). The average heat flux of U-tube is 149.9 kW/m2. The maximum cross flow velocity and cross flow energy (ρu2) through the U-bend region are 4.06 m/s and 1 145 J/m3, respectively.

关键词： Porous materials

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Sensitive detection of iodine by low pressure and short pulse laser-induced breakdown spectroscopy (LIBS)

Sensitive detection of iodine by low pressure and short puls...

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作者： Zhang, Xiaobo Deguchi, Yoshihiro Wang, Zhenzhen Yan, Junjie Liu, Jiping State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an 710049 China Graduate School of Advanced Technology and Science University of Tokushima Tokushima 770-8501 Japan

In this study, Laser-Induced Breakdown Spectroscopy (LIBS) technology was applied to detect iodine, an essential element for human body. Iodine in buffer gases of N2 and air was detected using nanosecond and picosecond breakdowns of CH3I at reduced pressure. Compared with the conventional methods of iodine measurement, LIBS technology without sample preparation shows the merits of fast response, real-time detection and enhanced detection limit. The measurement results of iodine demonstrated that low-pressure LIBS is the favourable method for trace species measurement in analytical applications. The plasma generation processes of multi-photon ionization and electron impact ionization can be controlled by pressure and laser pulse width for the larger ionization and excitation processes of iodine, which was discussed by the intensity ratio of iodine emission at 183 nm to nitrogen emission at 174.3 nm. The detection limit of iodine measurement in N2 was 60 ppb in nanosecond breakdown at 700 Pa. Iodine in air as the buffer gas was also detected using nanosecond and picosecond breakdowns to examine the effect of oxygen. This journal is © the Partner Organisations 2014.

关键词： Impact ionization

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Simulation Investigation on the Dynamic Characteristics of a 600MW Supercritical Lignite-fired Pulverized Boiler

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Energy Procedia 2014年 61卷 1434-1437页

作者： Xiaoqu Han Zhaonan Xue Ming Liu Junjie Yan Jinshi Wang Daotong Chong Jiping Liu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

The real-time dynamic simulation model of a 600MW lignite-fired pulverized boiler, which is a supercritical once-through boiler with fan mill three drying media direct fired system, was established. The step reduction of hot flue gas flow rate was simulated. The dynamic responses of live and reheat steam temperatures were obtained and analyzed. Results show that the response of steam temperature is an oscillation process. The superheat and reheat steam overtemperature values are influenced by the boiler load, the hot flue gas extracting percent and the inertia time of pulverizing system.

关键词： Simulation Dynamic Characteristics Hot Flue Gas Extracting Percent Steam Overtemperature

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Study on Steam-Water Solar Cavity Receiver

Study on Steam-Water Solar Cavity Receiver

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2014第四届国际新能源产业大会——主题：助力一个美丽、洁净、可持续发展的家园

作者： Jinjia Wei State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

Solar energy is clean without pollution,rich and free,so solar thermal power has the huge potential for future energy *** type concentrating technology can be used for large-scale solar power *** the power tower system,the heat receiver is the key equipment for sunlightheat *** thermal performance of the receiver will affect the efficiency of the entire power *** is no rich experience on the design of receiver,which is mainly based on the coal-fired *** to the non-uniform and instantaneous characteristics of sunlight,the receiver should differ greatly from the conventional coal-fired *** it is necessary to study the receiver according to the sunlight *** experiment platform for testing the thermal performance of a water/steam cavity receiver was firstly designed and *** start-up curves under different operating pressures were obtained and the receiver has low thermal efficiency of only about 55-70%.The low thermal efficiency is attributed to the low mass flow rate.A combined method was proposed to evaluate the thermal performance of the cavity receiver for start up and *** numerical results are in good agreement with the *** results suggested that an appropriate mass flow rate of 200 kg/h should be chosen for the design and operation of the experiment *** thermal performance of a solar cavity receiver under windy conditions was numerically *** heat flux and temperature distributions on boiling tubes in the cavity were *** convective and radiative heat losses were analyzed in *** the wind flow angle or velocity can obviously affect the air velocity inside the cavity,which reaches the maximum value for side on wind,resulting in a large convective heat *** on the experimental and numerical studies,a water/steam cavity receiver was designed and *** receiver is now being used in 1MW power tower plant in China with a

关键词： Study on Steam-Water Solar Cavity Receiver

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Ausgeprägte Nahordnung in kleinen amorphen Calciumcarbonat‐Clustern (<2 nm)

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Angewandte Chemie 2016年第40期128卷

作者： Shengtong Sun Daniel M. Chevrier Peng Zhang Denis Gebauer Helmut Cölfen Physikalische Chemie Universität Konstanz Universitätsstraße 10 78457 Konstanz Deutschland School of Chemical Engineering State Key Laboratory of Chemical Engineering Shanghai Key Laboratory of Multiphase Materials Chemical Engineering East China University of Science and Technology 130 Meilong Road Shanghai 200237 Volksrepublik China Department of Chemistry and Institute for Research in Materials Dalhousie University Halifax Nova Scotia B3H 4R2 Kanada

Amorphe Zwischenphasen sind wichtige Vorstufen bei der Kristallisation vieler biogener Minerale. Obwohl bereits gezeigt werden konnte, dass amorphe Calciumcarbonate (ACC) eine inhärente Nahordnung aufweisen, die unterschiedlichen kristallinen Formen zugeordnet werden kann, wurde bisher noch nie experimentell bestätigt, ob solche Nahordnungen bereits in sehr kleinen Clustern (<2 nm) vorkommen. Hier wurde die Stabilität und Struktur von 10,12‐Pentacosadiinsäure(PCDA)‐geschützten ACC‐Clustern untersucht, die eine Kerngröße von ca. 1.4 nm aufweisen und aus nur 7 CaCO 3 ‐Einheiten bestehen. Die Ligandenkonzentration und ‐struktur spielt eine Schlüsselrolle bei der Stabilisierung dieser ACC‐Cluster. Schon solch kleine CaCO 3 ‐Einheiten weisen eine Proto‐Calcit‐Nahordnung auf, wenn auch mit relativ hoher Unordnung. Dies legt nahe, dass ein struktureller Zusammenhang zwischen Pränukleationsclustern, amorphen Zwischenstufen und dem fertigen kristallinen Polymorph besteht.

关键词： Amorphe Materialien Calciumcarbonat-Cluster Carboxylatliganden EXAFS Nahordnung

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Thermodynamic Analysis on a Pre-dried Lignite-fired Power System: Comparison on Energy Supply Systems for Dryer

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Energy Procedia 2014年 61卷 1424-1427页

作者： Ming Liu Junjie Yan Jinshi Wang Daotong Chong Jiping Liu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

Pre-drying is a potential way to improve the electric generation efficiency of lignite-fired power plant, and steam is a main kind of drying heat source. In conventional pre-dried lignite-fired power system, the steam extraction of regenerative system is led to the dryer directly. The steam extraction must be used by the dryer after throttling, if the energy mismatch exists between the supply of steam extraction and the need of dryer. Two systems of energy supply for the dryer, that the energy of the steam extraction is supplied to the dryer via compressor or ejector, were proposed in this paper to further increase the energy utilization efficiency. These systems were thermodynamic analyzed, and the electric generation efficiencies of these systems were compared. The energy saving boundary was gotten.

关键词： Thermodynamics Lignite pre-drying Compressor Ejector

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Automatic calibration method of voxel size for cone-beam 3D-CT scanning system

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Chinese Physics C 2014年第4期38卷 69-74页

作者：杨民王晓龙刘义鹏孟凡勇李兴东刘文丽魏东波 School of Mechanical Engineering and Automation Beijing Univ.of Aeronautics and Astronautics Department of Control Science and Engineering Harbin Institute of Technology State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of Sciences National Institute of Metrology

For a cone-beam three-dimensional computed tomography （3D-CT） scanning system, voxel size is an important indicator to guarantee the accuracy of data analysis and feature measurement based on 3D-CT images. Meanwhile, the voxel size changes with the movement of the rotary stage along X-ray direction. In order to realize the automatic calibration of the voxel size, a new and easily-implemented method is proposed. According to this method, several projections of a spherical phantom are captured at different imaging positions and the corresponding voxel size values are calculated by non-linear least-square fitting. Through these interpolation values, a linear equation is obtained that reflects the relationship between the voxel size and the rotary stage translation distance from its nominal zero position. Finally, the linear equation is imported into the calibration module of the 3D-CT scanning system. When the rotary stage is moving along X-ray direction, the accurate value of the voxel size is dynamically exported. The experimental results prove that this method meets the requirements of the actual CT scanning system, and has virtues of easy implementation and high accuracy.

关键词： cone-beam CT voxel size least square fitting automatic calibration

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Quantitative detection of molds counts in cigarette cut tobacco at early stages by an electronic nose

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Sensor Letters 2014年第1期12卷 56-63页

作者： Zhu, Chao Huang, Kaijin Yuan, Fangli Xie, Changsheng State Key Laboratory of Materials Processing and Die and Mould Technology Huazhong University of Science and Technology Wuhan 430074 China State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Science Beijing 100190 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

Cigarette cut tobacco mildew will cause tremendous economic loss and human health. An improved electronic nose was developed to detect cigarette cut tobacco mildew at early stages. After storing 96 h at 30 °C and 90% RH, the molds counts in dry cigarette cut tobacco was 1.6×104 CFU/g which is much higher than the mildew threshold of 2.5×103 ˜ 3.0×103 CFU/g. Cluster analysis and loading analysis were applied to optimize the gas sensor array. For the results of canonical discriminant function analysis (DFA), both of the original sensor array and the optimized sensor array had high overall correct classification rate (96.7%). For the results of multilayer perceptron neural network (MLPNN), the correlation coefficient of the real molds counts and the prediction molds counts increased from 0.99508 to 0.99612 and the average relative error decreased from 0.42% to 0.25%. The excellent performance of the electronic nose makes it a good choice to play as a rapid and effective method to quantitatively detect molds counts in cigarette cut tobacco at early stages. Copyright © 2014 American Scientific Publishers.

关键词： Tobacco

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A CFD Simulation of 3D Air flow and Temperature Variation in Refrigeration Cabinet

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Procedia engineering 2015年 102卷 1599-1611页

作者： Limin Wang Lin Zhang Guoping Lian State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 China Unilever R&D Colworth Sharnbrook Bedford MK44 1LQ UK Department of Chemical and Process Engineering University of Surrey Guildford GU2 7XH UK

Presented is a 3D simulation of the air flow and temperature variation in an ice drink refrigeration cabinet, during an automated dynamic cycle of switching on and switching off. To correctly model the effect of perforated plate separating evaporator and storage compartments, a benchmark problem is designed, and used as a reference to determine the parameters in the porous-jump model by parameter optimization. Subsequently, the dynamic cycle of initial switch on, automated switch off and automated switch on is simulated. Both the flow field distribution and temperature profile are analyzed and the time required for these three stages is obtained. Full 3D CFD simulation of refrigeration system provides not only detailed temperature distribution in the cabinet but also operational parameters of the system such as for switch on-off cycle. Those output from simulation are important for cabinet design to improve the storage quality of products while reducing the energy use.

关键词： Refrigeration cabinet CFD Dynamic cycle Perforated plate

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A new approach to modelling heat transfer in a fixed bed by coupling characteristic: Packing information from DEM to CFD 3rd

A new approach to modelling heat transfer in a fixed bed by ...

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International Conference on Computational Methods for Thermal Problems, ThermaComp 2014

作者： Zhang, Nan Liu, Xiaoxing Zhang, Cun Xu, Guangwen State Key Laboratory of Multiphase Complex System Institute of Process Engineering Chinese Academy of Sciences Beijing100190 China

ISBN: (纸本)9788874317271

A DEM-CFD coupled approach were proposed to joint the advantage of discrete models of providing detailed packing information and continuous models of realizing macro-scale simulations. DEM simulation of particle packing in a small-scale fixed bed was first validated, then the model was used on particle packing in a lab-scale fixed bed with internals, statistics voidage distribution was obtained and coupled with Eulerian Granular multiphase Model, realized the maro-scale simulation of fixed beds of considering the meso-scale packing structure.

关键词： Heat transfer

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