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Journal of Thermal Science 2011年第4期20卷 343-348页

作者： wu xuezhi Liu Jie Xu Xiang Xiao Yunhan Key Laboratory of Advanced Energy and Power （Institute of Engineering Thermophysics） Chinese Academy of Sciences Beijing 100190 Graduate University of Chinese Academy of Sciences Beijing 100190

High inlet solid loading is one of the most important features of cyclone separators in high density circulating fluidized beds （CFB）. In this work, the effect of high solid loading on pressure drop in a reverse-flow cyclone was experimentally studied. The particles used were sand and 2zAl203. Art extended range of inlet solid loadings （M）, up to 30 kg of solids/kg of air was tested at different inlet air velocities （Vin=16~24 m/s）, well beyond the solid loading range reported before. The experiments showed that, in the tested range of solid loadings, the cyclone pressure drop decreased dramatically with increasing solid loading when M〈7.5 kg/kg and then almost remained constant. A new semi-empirical model for predicting cyclone pressure drop was also developed. The calculated and experimental results showed good agreement for particle free flow and particle laden flow.

关键词： high inlet solid loading pressure drop reverse-flow cyclone modeling.

CFD simulation of smooth and T-abrupt exits in circulating fluidized bed risers

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Particuology 2010年第4期8卷 343-350页

作者： xuezhi wu Fan Jiang Xiang Xu Yunhan Xiao Key Laboratory of Advanced Energy and Power Institute of Engineering Thermophysics Chinese Academy ofSdences Beijing 100190 China Graduate University of the Chinese Academy ofSdences Beijing 100049 China

Gas-solid flow in circulating fluidized bed （CFB） risers depends not only on operating conditions but also on exit configurations. Few studies investigated the effects of exit configurations on flow structure using computational fluid dynamics （CFD）. This paper provides a 2D two-fluid model to simulate a cold bench-scale square cross-section riser with smooth and T-abrupt exits. The drag force between the gas and solid phases plays an important role in CFD. Since the drag force model based on homogeneous two- phase flow, such as the Wen-Yu correlation, could not capture the heterogeneous structures in gas-solid flow, the structure-dependent energy-minimization multi-scale （EMMS） drag force model （Wang, Ge, ＆ Li, 2008）, applicable for Geldart B particles （sand）, was integrated into the two-fluid model. The calculated axial solids hold-up profiles were respectively exponential curve for smooth exit and C-shaped curve for T-abrupt exit, both consistent with experimental data. This study once again proves the key role of drag force in CFD simulation and also shows the validity of CFD simulation （two-fluid model） to describe exit effects on ~as-solid flow in CFB risers.

关键词： T-abrupt exit Smooth exit Gas-solid flow CFBEMMS drag force model

3D full-loop simulation and experimental verification of gas-solid flow hydrodynamics in a dense circulating fluidized bed

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Particuology 2014年第5期12卷 218-226页

作者： Xueyao Wang xuezhi wu Fulin Lei Jing Lei Yunhan Xiao Key Laboratory of Advanced Energy and Power Institute of Engineering Thermophysics Chinese Academy of Sdences Beijing 100190 China Research Center for Clean Energy and Power Chinese Academy of Sciences Lianyungang Jiangsu 222069 China School of Energy & Power Engineering North China Electric Power University Changping District Beijing 102206 China

Because of their advantages of high efficiency and low cost, numerical research methods for large-scale circulating fluidized bed （CFB） apparatus are gaining ever more importance. This article presents a numer- ical study of gas-solid flow dynamics using the Eulerian granular multiphase model with a drag coefficient correction based on the energy-minimization multi-scale （EMMS） model. A three-dimensional, full-loop, time-dependent simulation of the hydrodynamics of a dense CFB apparatus is performed. The process parameters （e.g., operating and initial conditions） are provided in accordance with the real experiment to enhance the accuracy of the simulation. The axial profiles of the averaged solid volume fractions and the solids flux at the outlet of the cyclone are in reasonable agreement with experimental data, thereby verifying the applicability of the mathematical and physical models. As a result, the streamline in the riser and standpipe as well as the solids distribution contours at the cross sections is analyzed. Computational fluid dynamics （CFD） serves as a basis for CFB modeling to help resolve certain issues long in dispute but difficult to address experimentally. The results of this study provide the basis of a general approach to describing dynamic simulations of gas-solid flows.

关键词： Gas-solid flow Circulating fluidized bed EMMS method 3D full-loop simulation

Optimal planning of energy storage system in active distribution system based on fuzzy multi-objective bi-level optimization

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Journal of Modern Power Systems and Clean Energy 2018年第2期6卷 342-355页

作者： Rui LI Wei WANG Zhe CHEN xuezhi wu National Active Distribution Network Technology Research Center Beijing Jiaotong University Department of Energy Technology Aalborg University

A fuzzy multi-objective bi-level optimization problem is proposed to model the planning of energy storage system(ESS) in active distribution systems(ADS). The proposed model enables us to take into account how optimal operation strategy of ESS in the lower level can affect and be affected by the optimal allocation of ESS in the upper level. The power characteristic model of micro-grid(MG)and typical daily scenarios are established to take full consideration of time-variable nature of renewable energy generations(REGs) and load demand while easing the burden of computation. To solve the bi-level mixed integer problem, a multi-subgroup hierarchical chaos hybrid algorithm is introduced based on differential evolution(DE) and particle swarm optimization(PSO). The modified IEEE-33 bus benchmark distribution system is utilized to investigate the availability and effectiveness of the proposed model and the hybrid algorithm. Results indicate that the planningmodel gives an adequate consideration to the optimal operation and different roles of ESS, and has the advantages of objectiveness and reasonableness.

关键词： Active distribution system Energy storage system Optimal planning Bi-level programming Fuzzy multiple objective

Power flow control scheme for multiport power electronics transformers

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High Voltage 2018年第4期3卷 255-262页

作者： Huaitian Zhang Long Jing xuezhi wu Jiuchun Jiang Harith RWickramasinghe Georgios Konstantinou National Active Distribution Network Technology Research Center Beijing Jiaotong UniversityBeijingPeople's Republic of China Collaborative Innovation Center of Electric Vehicles in Beijing Beijing Jiaotong UniversityBeijingPeople's Republic of China School of Electrical Engineering and Telecommunications University of New South WalesSydneyNSW 2052Australia

Development of power electronics transformers(PETs)has made dc distribution and hybrid ac/dc systems a competitive solution for future network *** study focuses on the functions of a multiport PET interfacing medium-voltage and low-voltage networks.A comprehensive power flow control scheme based on a globalised multiport transmission model of the PET and droop control is *** allows for a coordinated energy exchange between the ports of the PET,which enables autonomous *** of the proposed approach in a hybrid ac/dc distribution network with different levels of distributed generation and loads verify the effectiveness of the method.

关键词： scheme flow power

A Hybrid Five-Level Single-Phase Rectifier with Low Common-Mode Voltage

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ZTE Communications 2023年第4期21卷 78-84页

作者： TIAN Ruihan wu xuezhi XU Wenzheng ZUO Zhiling CHEN Changqing Beijing Jiaotong University Beijing 100044China ZTE Corporation Shenzhen 518057China

Rectifiers with high efficiency and high power density are crucial to the stable and efficient power supply of 5G communication base stations,which deserves in-depth *** general,there are two key problems to be addressed:supporting both alternating current(AC)and direct current(DC)input,and minimizing the common-mode voltage as well as leakage current for safety *** this paper,a hybrid five-level single-phase rectifier is proposed.A five-level topology is adopted in the upper arm,and a half-bridge diode topology is adopted in the lower arm.A dual closed-loop control strategy and a flying capacitor voltage regulation method are designed accordingly so that the compatibility of both AC and DC input is realized with low common voltage and small passive *** and experimental results demonstrate the effectiveness and performance of the proposed rectifier.

关键词： multilevel rectifier 5L-ANPC low common-mode voltage AC-DC hybrid input

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Numerical simulation and experimental validation of gas–solid flow in the riser of a dense fluidized bed reactor

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Particuology 2009年第4期7卷 278-282页

作者： Xueyao Wang Fan Jiang xiang xu Shengdian Wang xuezhi wu Baoguo Fan Liangliang Liao Jiachang Wang Yunhan Xiao Key Laboratory of Advanced Energy and Power. Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100190 China

Gas-solid flow in the riser of a dense fluidized bed using Geldart B particles （sand）, at high gas velocity （7.6-15.5 m/s）s） and with comparatively high solid flux （140-333.8 kg]m^2 s）, was investigated experimentally and simulated by computational fluid dynamics （CFD）, both two- and three-dimensional and using the Gidaspow, O＇Brien-Syamlal, Koch-Hill-Ladd and EMMS drag models, The results predicted by EMMS drag model showed the best agreement with experimental results. Calculated axial solids hold-up profiles, in particular, are well consistent with experimental data. The flow structure in the riser was well represented by the CFD results, which also indicated the cause of cluster formation. Complex hydrody-namical behaviors of particle cluster were observed. The relative motion between gas and solid phases and axial heterogeneity in the three subzones of the riser were also investigated, and were found to be consistent with predicted flow structure. The model could well depict the difference between the two exit configurations used, viz., semi-bend smooth exit and T-shaped abrupt exit. The numerical results indicate that the proposed EMMS method gives better agreement with the experimental results as compared with the Gidaspow, O＇Brien-Syamlal, Koch-Hill-Ladd models. As a result, the proposed drag force model can be used as an efficient aporoach for the dense zas-solid two-ohase flow.

关键词： Gas-solid flow Drag model EMMS Exit configuration

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改进型微源下垂控制策略研究

电工技术学报 2014年第2期29卷 145-152,184页

作者：荆龙黄杏吴学智北京交通大学电气工程学院北京100044 ABB中国研究中心北京100015

传统无互联线微源"功率-电压-电流"三环下垂控制方法在微网系统中受到广泛关注,但其功率分配效果受线路阻感比的影响较为严重,文章分析了两种现有解决方案:利用参数调节使微源等效输出阻抗为感性的方法,其调节能力有限,优化效果不佳;利... 详细信息

传统无互联线微源"功率-电压-电流"三环下垂控制方法在微网系统中受到广泛关注,但其功率分配效果受线路阻感比的影响较为严重,文章分析了两种现有解决方案:利用参数调节使微源等效输出阻抗为感性的方法,其调节能力有限,优化效果不佳;利用虚拟阻抗串联改变微源输出阻抗的方法能大范围调节微源等效输出阻抗,但孤岛模式下微源输出端电压会出现明显跌落。为此本文在已有控制方法基础上,提出一种改进微源虚拟阻抗下垂控制策略,将虚拟阻抗等效为虚拟同步发电机电抗,利用虚拟阻抗压降实现微源输出电压的下垂特性,减小了微源的电压跌落。该策略无Q-V下垂控制外环,控制简单。最后通过仿真以及微源并联实验,对改进前后控制方法的性能进行了对比,证明了所提出方法的有效性。

关键词：微网分布式电源下垂控制虚拟阻抗虚拟同步发电机

液相烧结大晶粒UO_(2)及其烧结动力学分析

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材料导报 2023年第S1期37卷 42-45页

作者：吴学志中国原子能科学研究院反应堆工程技术研究所北京102413

大晶粒二氧化铀(UO_(2))芯块因具有低辐照肿胀、低裂变气体释放及优异的燃料包壳相互作用效应(PCI),而成为未来先进反应堆关注的候选燃料。本文采用液相烧结工艺制备大晶粒UO_(2)芯块,研究了液相烧结对UO_(2)芯块烧结性能、显微结构和... 详细信息

大晶粒二氧化铀(UO_(2))芯块因具有低辐照肿胀、低裂变气体释放及优异的燃料包壳相互作用效应(PCI),而成为未来先进反应堆关注的候选燃料。本文采用液相烧结工艺制备大晶粒UO_(2)芯块,研究了液相烧结对UO_(2)芯块烧结性能、显微结构和烧结动力学的作用机制和影响规律。结果表明:通过添加金属铀粉形成的液相烧结可明显促进UO_(2)芯块的致密化速度,液相烧结UO_(2)芯块的烧结特征指数为2.937,烧结机理主要为晶界扩散,烧结激活能为103.00 kJ/mol,低于普通UO_(2)芯块的烧结激活能(110.65 kJ/mol);液相烧结UO_(2)芯块晶粒生长指数为2.831,晶粒生长活化能为463.97 kJ/mol,低于普通UO_(2)芯块晶粒生长激活能(510 kJ/mol),加入的金属铀粉形成的液相烧结可促使晶粒长大;添加金属铀粉液相烧结工艺具有不引入非铀杂质元素、加快芯块致密化速度和增大芯块晶粒尺寸的多重作用。

关键词：大晶粒二氧化铀金属铀液相烧结烧结机理

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从核心作者测评看《图书馆》期刊学术影响

科技管理研究 2013年第12期33卷 246-250页

作者：吴雪芝首都师范大学图书馆北京100089

以作者发文量和被引量及期刊H指数合理确定核心作者候选人样本数据,并依据综合指数法对两个以上的指标设置合理的权重,确定1992-2011年《图书馆》期刊的核心作者261位。从核心作者发文年度分布的阶段发展状况、核心作者的机构地域分布... 详细信息

以作者发文量和被引量及期刊H指数合理确定核心作者候选人样本数据,并依据综合指数法对两个以上的指标设置合理的权重,确定1992-2011年《图书馆》期刊的核心作者261位。从核心作者发文年度分布的阶段发展状况、核心作者的机构地域分布状况等方面分析展示《图书馆》期刊的学术影响。

关键词：核心作者《图书馆》学术影响综合测评