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Bed inventory balance and stability of dual circulating fluidized bed systems

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Particuology 2024年第1期84卷 98-106页

作者： Yangjun Wei Leming Cheng David Pallares Bo Leckner Institute for Thermal power Engineering State Key Laboratory of Clean Energy UtilizationZhejiang UniversityHangzhou310027China Department of Space Earth and EnvironmentChalmers University of TechnologyS-41296GöteborgSweden

Experiments and modelling are conducted for general understanding on the imbalance phenomenon and for discussion on the strategies to improve the bed inventory balance and stability of a dual circulating fluidized bed(DCFB)*** experiments are carried out in a 15.5 m high pilot-scale DCFB cold test system.A fluid-dynamic DCFB model is developed based on a 1.5-dimensional semi-empirical model of an industrial CFB boiler,validated by experimental *** effects of control methods and operation conditions on the bed inventory balance and on the stability of the pilot-and large-scale DCFB systems are discussed.A"stable-unbalanced"state,where the system reaches a steady state,consisting of un-balanced bed inventories,is observed in both experiments and model *** maintain a balanced state and similar bed inventory in the DCFB systems with similar cross-sectional areas,it is recom-mended to keep similar total pressure drops or gas velocities in both reactors.

关键词： Bed inventory balance Stability dual circulating fluidized bed(DCFB) Experiment Modelling

Characteristics of perfluoromethyl vinyl ether:A new eco-friendly alternative gas for SF_(6)

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High Voltage 2024年第3期9卷 509-517页

作者： Song Xiao Yijiang Chen Mingjun Tang Shuangshuang Tian Haoran Xia Yifan Wang Ju Tang Yi Li Xiaoxing Zhang State key laboratory of power Grid Environmental Protection School of Electrical Engineering and AutomationWuhan UniversityHubeiChina key laboratory for High-Efficiency Utilization of Solar Energy and Operation Control of Energy Storage System School of Electrical and Electronic EngineeringHubei University of TechnologyWuhanChina

The exploration of eco-friendly insulating gas to substitute the most potent greenhouse gas sulphur hexafluoride(SF6)has consistently garnered significant ***,the au-thors evaluated the feasibility of utilising perfluoromethyl vinyl ether(PMVE,C_(3)F_(6)O)as a new branch of eco-friendly insulating gas for the first *** primary dielectric and stability characteristics of PMVE regarding AC breakdown,partial discharge,dielectric recovery,and decomposition properties were revealed under various gas pressure and electrical field *** was found that PMVE demonstrated superior dielectric strength,with the AC breakdown and PD inception voltage(PDIV)1.10 and 1.14 times that of pure SF_(6).Furthermore,the dielectric strength of PMVE exhibits stability even after undergoing 100 cycles of AC breakdowns,and there is no observable formation of solid precipitation on the electrode *** discharge decomposition of PMVE mainly generates fluorocarbon(CF_(4),C_(2)F_(6),C_(3)F_(6),C_(3)F_(8),etc.)and ***,the exceptional insulation stabilityandno absence of solidprecipitation featuresendow PMVE tobe utilised as a new eco-friendly gas for SF_(6)-free gas-insulated equipment.

关键词： surface dielectric vinyl

Compliance motion control of the hydraulic dual-arm manipulator with adaptive mass estimation of unknown object

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Frontiers of Mechanical Engineering 2024年第1期19卷 35-52页

作者： Bolin SUN Min CHENG Ruqi DING Bing XU State key laboratory of Mechanical Transmissions Chongqing UniversityChongqing 400044China key laboratory of Conveyance and Equipment(Ministry of Education) East China Jiaotong UniversityNanchang 330013China State key laboratory of Fluid power and Mechatronic Systems Zhejiang UniversityHangzhou 310027China

Given the limited operating ability of a single robotic arm,dual-arm collaborative operations have become increasingly *** with the electrically driven dual-arm manipulator,due to the unknown heavy load,difficulty in measuring contact forces,and control complexity during the closed-chain object transportation task,the hydraulic dual-arm manipulator(HDM)faces more difficulty in accurately tracking the desired motion trajectory,which may cause object deformation or even *** overcome this problem,a compliance motion control method is proposed in this paper for the *** mass parameter of the unknown object is obtained by using an adaptive method based on velocity *** to the difficulty in obtaining the actual internal force of the object,the pressure signal from the pressure sensor of the hydraulic system is used to estimate the contact force at the end-effector(EE)of two hydraulic manipulators(HMs).Further,the estimated contact force is used to calculate the actual internal force on the ***,a compliance motion controller is designed for HDM closed-chain *** position and internal force errors of the object are reduced by the feedback of the position,velocity,and internal force errors of the object to achieve the effect of the compliance motion of the HDM,i.e.,to reduce the motion error and internal force of the *** required velocity and force at the EE of the two HMs,including the position and internal force errors of the object,are inputted into separate position *** addition,the position controllers of the two individual HMs are designed to enable precise motion control by using the virtual decomposition control ***,comparative experiments are carried out on a hydraulic dual-arm test *** proposed method is validated by the experimental results,which demonstrate improved object position accuracy and reduced internal force.

关键词： hydraulic dual-arm manipulator compliance motion control unknown object adaptive mass estimation nonlinear control

Dynamic characteristics and application of dual throat fluidic thrust vectoring nozzle

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Chinese Journal of Aeronautics 2024年第9期37卷 85-99页

作者： Buxian XU Dongping HU Lihao FENG Fluid Mechanics key laboratory of Ministry of Education Beihang UniversityBeijing 100191China State key laboratory of Clean and Efficient Turbomachinery power Equipment Dongfang Electric Corporation Dongfang Turbine Co.LTDDeyang 618000China

Thrust vectoring technology plays an important role in improving the maneuverability of *** order to overcome the disadvantages of mechanical thrust vectoring nozzles,such as complications of structure and significant increases in weight and cost,fluidic thrust vectoring noz-zles are *** Throat fluidic thrust vectoring Nozzle(DTN)has received wide attention due to its excellent thrust vectoring efficiency and minimal thrust *** this study,three-dimensional unsteady numerical simulations of a single axisymmetric DTN are conducted first to analyze its dynamic *** the pitch and yaw control characteristics of DTN equipped on a flying-wing aircraft are *** is found that the dynamic response will experience three stages:rapid-deflecting stage,oscillating stage,and steady stage.A complete recirculation zone forms at the end of the rapid-deflecting stage,which pushes the primary flow to attach to the wall opposite the secondary ***,the exhaust flow is *** terms of DTN's appli-cation,the DTN equipped on the flying-wing aircraft is capable of providing effective pitch and yaw moments at all angles of attack and Mach *** addition,continuous pitch and yaw moments can be obtained by adjusting the secondary mass flow *** control moment is gen-erated due to the asymmetrical pressure distribution of nozzle surface,which is mainly contributed by the pressure decrease on the secondary injection ***,the DTN equipped on the flying-wing aircraft has a relatively high thrust vectoring efficiency of around 5°/%and a thrust coefficient of around 0.95 when nozzle pressure ratio equals *** results provide an important theoretical basis for the practical application of DTN.

关键词： dual throat nozzle Dynamic response charac-teristic Flowcontrol Flying-wing aircraft

Broadband high-efficiency dielectric metalenses based on quasi-continuous nanostrips

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Opto-Electronic Advances 2024年第5期7卷 43-51页

作者： Xiaohu Zhang Qinmiao Chen Dongliang Tang Kaifeng Liu Haimo Zhang Lintong Shi Mengyao He Yongcai Guo Shumin Xiao key laboratory of optoelectronic technology and Systems of the Education Ministry of China Chongqing UniversityChongqing 400044China Ministry of Industry and Information technology key Lab of Micro-Nano Optoelectronic Information System Guangdong Provincial Key Laboratory of Semiconductor Optoelectronic Materials and Intelligent Photonic SystemsHarbin Institute of TechnologyShenzhen 518055China key laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education&Hunan Provincial key laboratory of Low-Dimensional Structural Physics and Devices School of Physics and ElectronicsHunan UniversityChangsha 410082China

Benefiting from the abrupt phase changes within subwavelength thicknesses,metasurfaces have been widely applied for lightweight and compact optical *** broadband and high-efficiency characteristics are highly attractive for the practical implementation of ***,current metasurface devices mostly adopt discrete micro/nano structures,which rarely realize both merits *** this paper,dielectric metasurfaces composed of quasi-continuous nanostrips are proposed to overcome this *** quasi-continuous nanostrips metasurface,a normal focusing metalens and a superoscillatory lens overcoming the diffraction limit are designed and experimentally *** quasi-continuous metadevices can operate in a broadband wavelength ranging from 450 nm to 1000nm and keep a high power *** average efficiency of the fabricated metalens reaches 54.24%,showing a significant improvement compared to the previously reported metalenses with the same *** proposed methodology can be easily extended to design other metadevices with the advantages of broadband and high-efficiency in practical optical systems.

关键词： broadband high-efficiency metalens sub-diffraction quasi-continuous

维普期刊数据库

Unlocking wear resistance in an ultrastrong dual-phase highentropy alloy by interface-constrained deformation of brittle Laves phases

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Friction 2024年第10期12卷 2389-2398页

作者： Fei LIANG Yixing SUN Hongyuan WAN Yong LI Wenhao LU Ao MENG Lei GU Zhaoping LUO Yan LIN Yaping ZHANG Xiang CHEN Nano and Heterogeneous Materials Center School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China key laboratory of power Beam Processing AVIC Manufacturing Technology InstituteBeijing 100024China Shenyang National laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

The pronounced brittleness of hard Laves phase intermetallics is detrimental to their tribological properties at room *** this study,we utilized a heterogeneous structure to engineer an ultrastrong dual-phase(Laves+B2)AlCoFeNiNb high-entropy alloy that exhibits a low wear rate(3.82×10-6 mm3/(N·m))at room *** wear resistance in the ball-on-disc sliding friction test with the counterpart of Al2O3 balls stems from the activated deformation ability in the ultrafine Laves lamellae under heterogeneous interface ***,as tribological stress intensifies,the surface deformation mechanism transitions from dislocation slip on the basal and pyramidal planes to a unique combination of local shear and grain rotation within the Laves *** study illuminates fresh perspectives for mitigating the embrittling effect of Laves phase intermetallics under tribological loading and for the development of wear-resistant materials.

关键词： wear resistance high-entropy alloy Laves phase heterogeneous structure

Effect of Inter-Stage Pressure on Performances of Two-Stage Transcritical CO2 Refrigeration Cycle with Dedicated Absorption dual-Subcooling and Mechanical Recooling

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Journal of Thermal Science 2024年第6期33卷 2179-2189页

作者： LI Zeyu HUANG Caoxuheng YIN Jianhui School of Electric power South China University of Technology Guangdong Province key laboratory of High Efficient and Clean Energy Utilization South China University of Technology Guangdong Province Engineering Research Center of High Efficient and Low Pollution Energy Conversion Ningbo Jetron technology Co.Ltd.

The two-stage transcritical CO2refrigeration cycle with dedicated dual-subcooling and mechanical recooling is *** inter-stage pressure is critical for such cycle performances;however,it has not been studied ***,the research aim is to disclose the effect of inter-stage pressure on performances of the proposed *** main work consists of four ***,the comparative study is performed to display advantages of the proposed ***,the key temperatures,heat and power consumptions as well as performance indicators for different inter-stage pressures are analyzed in detail,based on the parametric ***,the optimal inter-stage pressure for different conditions is obtained by the nonlinear direct search ***,the economic performance is *** is found that the compressor power of the proposed cycle drops by 12%,and the working temperature lower limit is reduced by 11℃.Furthermore,it is considered that the optimal inter-stage pressure is insensitive to the heat source *** novelty lies in illustrating the effect of inter-stage pressure,obtaining trends of the optimal value,and pointing out the system *** paper is favorable for design and operation optimization of the proposed system.

关键词： CO2 refrigeration dedicated absorption subcooling recooling thermodynamics two-stage cycle

Identification of the Worst-case Static Voltage Stability Margin Interval of AC/DC power System Considering Uncertainty of Renewables

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CSEE Journal of power and Energy Systems 2024年第3期10卷 974-987页

作者： Wanbin Liu Shunjiang Lin Yuerong Yang Mingbo Liu Qifeng Li School of Electric power Engineering South China University of TechnologyGuangzhou 510640China Guangdong key laboratory of Clean Energy technology South China University of TechnologyGuangzhou 511458China Department of Electrical and Computer Engineering University of Central FloridaOrlandoFL 32816USA CSEE IEEE

Calculation of static voltage stability margin(SVSM)of AC/DC power systems with lots of renewable energy sources(RESs)integration requires consideration of uncertain load growth and renewable energy generation *** paper presents a bi-level optimal power flow(BLOPF)model to identify the worst-case SVSM of an AC/DC power system with line commutation converter-based HVDC and multi-terminal voltage sourced converter-based HVDC transmission *** of uncertain load growth’s hypercone model and control mode switching of DC converter stations are considered in the BLOPF ***,uncertain RES output fluctuations are described as intervals,and two three-level optimal power flow(TLOPF)models are established to identify interval bounds of the system worst-case *** two TLOPF models are both transformed into max–min bi-level optimization models according to independent characteristics of different uncertain ***,transforming the inner level model into its dual form,max–min BLOPF models are simplified to single-level optimization models for direct *** results on the modified IEEE-39 bus AC/DC case and an actual large-scale AC/DC case in China indicate correctness and efficiency of the proposed identification method.

关键词： AC/DC power system control mode switching convex relaxation dual programming multi-level optimization optimal power flow static voltage stability margin

In Situ High-performance Gel Polymer Electrolyte with dual-reactive Cross-linking for Lithium Metal Batteries

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Energy & Environmental Materials 2024年第1期7卷 51-59页

作者： Fuhe Wang Honghao Liu Yaqing Guo Qigao Han Ping Lou Long Li Jianjie Jiang Shijie Cheng Yuancheng Cao School of Materials Science and Engineering Huazhong University Huazhong University of Science and technology Wuhan 430074China State key laboratory of Advanced Electromagnetic Engineering and technology School of Electrical and Electronic Engineering Huazhong University of Science and TechnologyWuhan 430074China State Grid Huzhou power Supply Company Huzhou 313000China Huzhou Electric power Design Institute Company Huzhou 311404China

Lithium metal batteries have been considered as one of the most promising next-generation power-support devices due to their high specific energy and output ***,the uncontrollable side-reaction and lithium dendrite growth lead to the limited serving life and hinder the practical application of lithium metal ***,a tri-monomer copolymerized gel polymer electrolyte(TGPE)with a cross-linked reticulation structure was prepared by introducing a cross-linker(polyurethane group)into the acrylate-based in situ polymerization *** soft segment of polyurethane in TGPE enables the far migration of lithium ions,and the-NH forms hydrogen bonds in the hard segment to build a stable cross-linked *** system hinders anion migration and leads to a high Li^(+)migration number(t_(Li^(+))=0.65),which achieves uniform lithium deposition and effectively inhibits lithium dendrite *** a result,the assembled symmetric cell shows robust reversibility over 5500 h at a current density of 1 mA cm^(-2).The LFP∷TGPE∷Li cell has a capacity retention of 89.8%after cycling 800 times at a rate of *** summary,in situ polymerization of TGPE electrolytes is expected to be a candidate material for high-energy-density lithium metal batteries.

关键词： gel polymer electrolytes hydrogen bonds in situ polymerization lithium metal batteries polyurethane

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