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Numerical simulations of high pressure carbon dioxide fluid fluidized beds

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Particuology 2023年第7期78卷 1-15页

作者： Wenjan Cai Xietian xia xiang Li xing Chen Zenghui Xu Huilin Lu School of Energy Science and Engineering Harbin Institute of TechnologyHarbin150001China China Construction Eco-Environmental Protection Technology Co. Ltd.Suzhou215100China

Hydrodynamics of carbon dioxide fluid-particle mixtures are predicted using a low density ratio-based kinetic theory of granular flow in high pressure carbon dioxide fluid fluidized beds.A coexistence of particle waves and particle aggregates exists along bed *** threshold to identify the occurrence of particle aggregates is suggested based on standard deviation of solid volume fractions in aggregative *** existence time fractions and frequencies of particle aggregates are predicted along axial *** effect of carbon dioxide fluid temperature and pressure on volume fraction and velocity distributions are analyzed at different inlet carbon dioxide velocities and particle densities in high pressure carbon dioxide fluidized *** results indicate that the carbon dioxide-particles fluidization transits from particulate to aggregative states with the increase of inlet carbon dioxide *** computed fluid volume fractions and heterogeneity indexes are close to the measurements in a high pressure carbon dioxide fluidized bed.

关键词： High pressure carbon dioxide Fluidized bed Transition Aggregative fluidization Particulate fluidization Kinetic theory of granular flow

Ion thruster accelerator grid erosion mechanism under extreme conditions of cylindrical erosion and chamfer erosion

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Chinese Journal of Aeronautics 2023年第6期36卷 128-139页

作者： Guangqing xia Jiahui LI Chang LU Hai geng Vladimir A.SAETCHNIKOV Juan LI Yanlong WANG State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentDalian University of TechnologyDalian 116024China Key Laboratory of Advanced Technology for Aerospace Vehicles of Liaoning Province Dalian University of TechnologyDalian 116024China Collaborative Innovation Center of Micro&Nano Satellites of Hebei Province North China Institute of Aerospace EngineeringLangfang 065000China Science and Technology on Vacuum Technology and Physics Laboratory Lanzhou Institute of PhysicsLanzhou 73000China Physics and Aerospace Technology Department Belarusian State UniversityMinsk 220030Belarus

In this paper,the abnormal experimental phenomenon on barrel erosion under extreme working conditions in the ultra-long life experiment(>10000 h)of ion thruster ion optics is studied by the Immersed-Finite-Element Particle-In-Cell Monte-Carlo-Collision(IFE-PIC-MCC)method and the grid erosion evaluation *** transport process of beam ions and Charge Exchange(CEX)ions in the grid system,and the characteristics and mechanisms of the aperture barrel erosion under extreme erosion conditions(*** cylindrical erosion and chamfer erosion)were systematically *** to the advantage of the IFE method for dealing with complex boundaries in structured mesh,the aperture barrel erosion morphology of the accelerator grid is reconstructed accurately based on the experimental *** results show that,with the evolution of working conditions,the mechanism of the aperture barrel erosion changes significantly,which relies heavily on the accelerator grid *** change of the accelerator grid aperture barrel morphology has a significant effect on the behavior of CEX ions,and only affects the local electric field distribution,but has no effect on the upstream plasma *** the erosion progresses,the erosion position moves downstream along the grid aperture axis direction,and the erosion range becomes *** of the erosion phase,the erosion rate of the CEX ions located downstream of the decelerator grid is the *** erosion rate is related to the mean incident energy and angle,and their variation is closely related to the position and trajectory of CEXions.

关键词： Accelerator grid Charge Exchange(CEX)ions Erosion IFE-PIC-MCC Ion propulsion

Dense copper azide synthesized by in-situ reaction of assembled nanoporous copper microspheres and its initiation performance

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Defence Technology（防务技术） 2022年第6期18卷 1065-1072页

作者： xing-yu Wu Ming-yu Li Qing-xuan Zeng Qing-xia Yu State Key Laboratory of Explosion and Technology Beijing Institute of TechnologyBeijing100081PR China

Copper azide with high density was successfully synthesized by in-situ reaction of nanoporous copper(NPC)precursor with HN_(3) *** with pore size of about 529 nm has been prepared by electroless plating using polystyrene(PS)as *** copper shells thickness of NPC was controlled by adjusting the PS loading *** effects of copper shell on the morphology,structure and density of copper azide were *** conversion increased from 87.12%to 95.31%when copper shell thickness decrease from 100 to 50 ***,the density of copper azide prepared by 529 nm NPC for 24 h was up to 2.38 g/cm^(3).The hollow structure of this NPC was filled by swelling of copper azide which guaranteed enough filling volume for keeping the same shape as well as improving the charge ***,HNS-IV explosive was successfully initiated by copper azide with minimum charge thickness of 0.55 mm,showing that copper azide prepared has excellent initiation performance,which has more advantages in the application of miniaturized explosive systems.

关键词： Nanoporous copper Electroless plating In-situ reaction Copper azide

Gas template-assisted spray pyrolysis： A facile strategy to produce porous hollow Co3O4 with tunable porosity for high-performance lithium-ion battery anode materials

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Nano Research 2018年第3期11卷 1490-1499页

作者： Haoran Du Kuangfu Huang Min Li Yuanyuan xia Yixuan Sun Mengkang Yu Baoyou geng College of Chemistry and Materials Science Anhui Key Laboratory of Functional Molecular Solids Ministry of Education Anhui Laboratory of Molecular-Based Materials Center for Nano-Science and Technology Anhui Normal University Wuhu 241000 China

Porous hollow Co3O4 microspheres have been synthesized from a mixed cobalt nitrate and urea solution through spray pyrolysis followed by calcination at 600 ℃ in air. This porous hollow Co3O4 is assembled by nanoparticles and exhibits variable porosity depending on the amount of gas in the system. In pyrolysis process, urea continuously decomposes into gaseous components, which act as a template to control the porous structure. The amount of gas escaping from precursor droplets can directly influence the porosity of the microspheres and the size of the nanoparticles controlled by the ratio of urea to cobalt nitrate. Electrochemical measurements show that the performance of the porous hollow Co3O4 microspheres is related to the porosity and size of the nanopartides. The sample with optimal porosity delivers a high first charge capacity of 1,417.9 mAh·g^-1 at 0.2C （1C = 890 mA·g^-1）, and superior charge cycle performance of 1,012.7 mAh.g-1 after 100 cycles. In addition, the optimized material displays satisfactory rate performance of 1,012.4 mAh.g-1 at 1C after 50 cycles and 881.3 mAh·g^-1 at 2C after 300 cycles. Superior charge/discharge capacity, excellent rate performance and high yield achieved in this study is promising for the development of high-performance Co3O4 anode materials for lithium-ion batteries.

关键词： Co3O4/gas template tunable porosity spray pyrolysis anode lithium-ion batteries

Effect of Temperature on the Dynamic Recrystallization of AZ31 Alloy with Pulse Current

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Acta Metallurgica Sinica(English Letters) 2018年第12期31卷 1281-1286页

作者： Shu-xia Lin xing-Rong Chu Zhen-Ming Yue Jun Gao School of Mechanical Electrical and Information Engineering Shandong University

The tensile tests of AZ31 magnesium alloy were carried out under room temperature, 100, 150 and 200 ℃ with andwithout pulse current. The effect of temperature on dynamic recrystallization （DRX） of AZ31 alloy was studied at differentconditions. One-parameter approach was used to analyze the critical conditions of DRX, the critical stress was obtainedunder different temperatures, and the related results were validated by metallography observation. The results showed thatDRX of AZ31 alloy occurred at 200 ℃ without pulse current. When pulse current with 150 Hz/50 V parameter wasapplied at room temperature, DRX occurred, while DRX was not completed until temperature over 150 ~C. With theanalysis result of critical conditions of DRX based on one-parameter approach, the relationship between critical stress andpeak stress obtained in this present study is σc = （0.746-0.773）σp.

关键词： AZ31 alloy Electroplasticity Dynamic recrystallization One-parameter approach

Effect of Sodium Sulfate on Direct Reduction of Beach Titanomagnetite for Separation of Iron and Titanium

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Journal of Iron and Steel Research International 2016年第5期23卷 428-433页

作者： En-xia GAO Ti-chang SUN Zhi-guo LIU Chao geng Cheng-yan XU School of Civil and Environmental Engineering University of Science and Technology Beijing

The effect of sodium sulfate on direct reduction of beach titanomagnetite,followed by magnetic separation,to separate iron and titanium was investigated. Direct reduced iron（ DRI） with a high Fe content,low TiO_2 content and low iron recovery was obtained after adding sodium sulfate. When the sodium sulfate dosage was increased from 0 to 10 mass%,the Fe content of the DRI increased from 90. 00 mass% to 93. 55 mass% and the TiO_2 content decreased from 1. 27 mass% to 0. 70 mass%. The reduction mechanism of sodium sulfate was investigated by X-ray diffraction（ XRD） and scanning electron microscopy（ SEM） with energy dispersive spectrometer（ EDS）. Results revealed that the metallic iron grains in the reduced ore with sodium sulfate were larger than those in the ore without sodium sulfate. Sodium sulfate promoted the migration of iron as well as the accumulation and growth of metallic iron grains by low-melting-point carnegieite and troilite formed in the redox system. Low-melting-point carnegieite decreased the melting point of the system and then promoted liquefaction. Troilite could decrease the surface tension and melting point of metallic iron grains.

关键词： beach titanomagnetite sodium sulfate direct reduction separation iron titanium

Self-cleaning Anti-fouling TiO2/Poly(aryl ether sulfone) Composite Ultrafiltration Membranes

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Chemical Research in Chinese Universities 2019年第4期35卷 714-720页

作者： JIANG Hongchuan YANG xia FENG Yong WANG Xinyu geng Zhi HUO Mingxin Jilin Engineering Lab for Water Pollution Control and Resources Recovery College of EnvironmentNortheast Normal UniversityChangchun 130117P.R.China

A series of novel TiO2/poly(aryl ether sulfone) ultrafiltration membranes with anti-fouling and self-cleaning properties was designed and prepared. First, anti-photocatalytic degraded fluorine contained polv(aryl ether sulfone) matrix(PAES-F) was synthesized. Then the composite membranes were prepared via TiO2 nanopartides and PAES-F polymer matrix by solution blending and non-solvent induced phase inversion methods. Further, separation efficiency, fouling behavior and self-cleaning property of the composite ultrafiltration(UF) membranes were investigated by dead-end filtration experiments using a polyacn lamide solution. The composite UF membranes exhibited outstanding self-cleaning efficiency and anti-photocatalytic degraded property after exposure to simulated sunliglit *** water flux recovery ratios(FRR)of the optimal composite UF membranes could reach 74.24%, which was attributable to photocatalytic degradation of the organic contaminant by TiO2. And the retention rates of the composite UF membranes could maintain over 97%, which indicated the excellent photocatalytic degradation resistance of the fluorine contained PAES-F matrix. The novel high perfomiance composite UF membranes have a broad application prospect in water treatment.

关键词： Poly(aryl ether sulfone) Ultrafiltration Anti-fouling Self-cleaning Titanium dioxide

PROGRESS IN RESEARCH ON RIVER WATER CHEMISTRY IN CHINA

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Chinese Geographical Science 2000年第1期10卷 8-13页

作者： Jing-sheng Chen xing-hui xia Department of Urban & Environmental Sciences Peking University 100871 Beijing P.R. China

River water resource is the most important component of water resources in China. This paper reviews the progress in the research on river water chemistry in China. It includes three parts: 1) the development of river water quality monitoring in China (at present, there exist three water quality monitoring networks in China: near 3000 water quality monitoring stations under the Ministry of Water Resources, several thousands water quality monitoring sites under the State Environmental Protection Administration and four sites under the China’s GEMS/Water Program); 2) progress in the research on chemical characteristics of river water chemistry in China and their geographical roles on natio wide and region wide scales; and 3) progress in the research on river quality changes in the last 40 years (the long term monitoring data reveals that the water quality of the Changjiang River has acidification trend, the Songhuajiang River had alkalization trend, and the Huanghe River has concentration trend in the last 4 decades).

关键词： China’s river water chemistry water quality change

Structure-design and theoretical-calculation for ultrasmall Co_(3)O_(4) anchored into ionic liquid modified graphene as anode of flexible lithium-ion batteries

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Nano Research 2022年第3期15卷 2104-2111页

作者： Longda Cong Shichao Zhang Hengyao Zhu Weixin Chen Xueyan Huang Yalan xing Jun xia Puheng Yang xia Lu School of Materials Science and Engineering Beihang UniversityBeijing 100191China School of Physics Science and Nuclear Energy Engineering Beihang UniversityBeijing 100191China School of Materials Sun Yat-sen UniversityShenzhen 518107China School of Materials Science and Engineering Sun Yat-sen UniversityGuangzhou 510275China

Cobalt oxide(Co_(3)O_(4))is currently suitable in energy storage applications because of its high capacity based on the conversion reaction ***,unmodified Co_(3)O_(4)suffers from distinctly inferior rate capability and poor cycling *** the basis of the aforementioned considerations and density functional theory(DFT)simulations,the three-dimensional hierarchical porous structure(HPS)ultrasmall Co_(3)O_(4)anchored into ionic liquid(IL)modified graphene oxide(GO)has been successfully prepared(ultrasmall/Co_(3)O_(4)-GA-IL).The ultrasmall/Co_(3)O_(4)-GA-IL consists of Co_(3)O_(4)co-assembled with IL modified GO to generate the HPS which can facilitate ion transfer channels through reduction of the electron and ion transportation path and transmission *** addition,N-doping graphene can enhance the inherent electrical conductivity of Co_(3)O_(4),which is proved by the DFT *** virtue of the novel superstructure,the ultrasmall/Co_(3)O_(4)-GA-IL electrode demonstrates a high reversible capacity of 1,304 mAh·g^(−1),an enhanced high-rate capability(715 mAh·g^(−1)at 5 C),and a capacity retention of 98.4%even after 500 cycles at 5 C rate,which corresponds to 0.0003%capacity loss per *** cells based on the cathode are further fabricated and demonstrate excellent mechanical and electrochemical properties under bent and folded state,highlighting the practical application of our deliberately designed electrode in wearable electronics.

关键词： co-assembly ultrasmall cobalt oxide ionic liquid flexible lithium-ion batteries hierarchical porous structure density functional theory simulations