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Experimental and numerical studies of micro PEM fuel cell

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Acta Mechanica Sinica 2011年第5期27卷 627-635页

作者： Rong-gui Peng chen-Chung Chung Chiun-Hsun chen Department of Mechanical Engineering National Chiao Tung UniversityHsinchu Taiwan China

A single micro proton exchange membrane fuel cell （PEMFC） has been produced using Micro-electromechanical systems （MEMS） technology with the active area of 2.5 cm 2 and channel depth of about 500 μ m.A theoretical analysis is performed in this study for a novel MEMS-based design of a micro *** model consists of the conservation equations of mass,momentum,species and electric current in a fully integrated finite-volume solver using the CFD-ACE＋ commercial *** polarization curves of simulation are well correlated with experimental ***-dimensional simulations are carried out to treat prediction and analysis of micro PEMFC temperature,current density and water distributions in two different fuel flow rates （15 cm 3 /min and 40 cm 3 /min）.Simulation results show that temperature distribution within the micro PEMFC is affected by water distribution in the membrane and indicate that low and uniform temperature distribution in the membrane at low fuel flow rates leads to increased membrane water distribution and obtains superior micro PEMFC current density distribution under 0.4 V operating *** predictions are well within those known for experimental mechanism phenomena.

关键词： Micro PEMFC · MEMS · Simulation · Fuel flow rate

Formulation of grain growth diagram in simulated weld HAZ of Ti-microalloyed steel

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Acta Metallurgica Sinica(English Letters) 2009年第4期22卷 308-312页

作者： Chibin gui Qi chen Kun CUI Department of Naval Architecture and Ocean Engineering School of Naval Architecture and Power Engineering Navy University of Engineering Wuhan 430033 China

In this paper, the response of TiN particles to welding thermal cycle and the kinetic behavior of the grain growth in weld heat-affected zone of the Ti-microalloyed steel have been studied by using the simulation technology. Based on the theory of the TiN particle dissolution and coarsening kinetic models in weld thermal cycle and some metallographic data from thermal simulated samples, the grain growth diagram of Ti-microalloyed steel is presented. The experimental data from thermal simulated weld samples agreed well with the value of the diagram predicted.

关键词： Ti-microalloyed steel Grain growth in weld HAZ Simulation technology

On the horizontal distribution of algal-bloom in Chaohu Lake and its formation process

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Acta Mechanica Sinica 2014年第5期30卷 656-666页

作者： Yuan-Ying chen Qing-quan Liu Laboratory for Mechanics in Fluid Solid Coupling System Institute of Mechanics Chinese Academy of Sciences

Based on the remote sensing images of algae, the present work analyzes the horizontal distribution characteristics of algal blooms in Chaohu Lake, China, which also reveals the frequency of algal blooms under different wind directions. Further, an unstructured-grid, three-dimensional finite-volume coastal ocean model （FVCOM） is applied to investigate the wind-induced currents and the transport pro- cess to explain the reason why algal blooms occur at the detected places. We first deduce the primary distribution of biomass from overlaid satellite images, and explain the formation mechanism by analyzing the pollution sources, and simulating the flow field and transportation process under prevailing wind over Chaohu Lake. And then, we consider the adjustment action of the wind on the corresponding day and develop a two-time scale approach to describe the whole formation process of algae horizontal distribution in Chaohu Lake. That is, on the longer time scale, i.e., during bloom season, prevailing wind determines the primary distribution of biomass by inducing the characteristic flow field; on the shorter time scale, i.e., on the day when bloom occurs, the wind force adjusts the primary distribution of biomass to form the final distribution of algal bloom.

关键词： Chaohu Lake Algal bloom Horizontal distri- bution - Wind-driven current Two-time scale process

Symmetric Equations for Evaluating Maximum Torsion Stress of Rectangular Beams in Compliant Mechanisms

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Chinese Journal of Mechanical Engineering 2018年第1期31卷 34-40页

作者： gui-Min chen Larry L.Howell State Key Laboratory for Manufacturing Systems Engineering Xi'an Jiaotong University Department of Mechanical Engineering Brigham Young University

There are several design equations available for calculating the torsional compliance and the maximum torsion stress of a rectangular cross-section beam, but most depend on the relative magnitude of the two dimensions of the crosssection(i.e., the thickness and the width). After reviewing the available equations, two thickness-to-width ratio Independent equations that are symmetric with respect to the two dimensions are obtained for evaluating the maximum torsion stress of rectangular cross-section beams. Based on the resulting equations, outside lamina emergent torsional joints are analyzed and some useful design Insights are obtained. These equations, together with the previous work on symmetric equations for calculating torsional compliance, provide a convenient and effective way for designing and optimizing torsional beams in compliant mechanisms.

关键词： Compliant mechanism Maximum torsion stress Rectangular beam Lamina emergent joint

Influence of External Interface Normal Stress on the Growth of Cu-Sn IMC During Aging

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Acta Metallurgica Sinica(English Letters) 2020年第10期33卷 1388-1396页

作者： Changchang Wang Yinbo chen Zhi-quan Liu Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Shenzhen Institute of Advanced Electronic Materials Shenzhen Institutes of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China

A U-shape clamp was designed to apply stress perpendicular to the interface of Cu/Sn/Cu solder joints,and its influence on the growth behavior of Cu-Sn intermetallic compound(IMC)during thermal aging at 150℃ was *** results show that compared with the sample at general stress-free state,the growth rate of IMC under compression is faster,while that under tension is ***,the interface between IMC and Sn is smoother under compressive stress,and the corresponding IMC grains are smaller and more uniform than that under tensile *** to the growth kinetic analysis,the growth of IMC under general,compressive and tensile states is all controlled by the combination of grain boundary diffusion and volume diffusion with a similar growth exponent(n≈0.4).However,external stress can affect the Ostwald ripening process of grain growth,causing a change of grain size and grain boundary density in the IMC *** a result,the IMC growth behavior at the interface of the solder joint will be affected by the applied external normal stress.

关键词： Cu-Sn IMC Growth behavior External stress effect Isothermal aging

Mineral-phase evolution and sintering behavior of MO–SiO_2–Al_2O_3–B_2O_3 (M = Ca,Ba) glass-ceramics by low-temperature liquid-phase sintering

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International Journal of Minerals,Metallurgy and Materials 2018年第9期25卷 1042-1054页

作者： Song chen Zhen Sun De-gui Zhu School of Materials Science and Engineering Southwest Jiaotong University

In this work, network former SiO_2 and network intermediate Al_2O_3 were introduced into typical low-melting binary compositions CaO·B_2O_3, CaO·2B_2O_3, and BaO·B_2O_3 via an aqueous solid-state suspension milling route. Accordingly, multiple-phase aluminosilicate glass-ceramics were directly obtained via liquid-phase sintering at temperatures below 950°C. On the basis of liquid-phase sintering theory, mineral-phase evolutions and glass-phase formations were systematically investigated in a wide MO–SiO_2–Al_2O_3–B_2O_3(M = Ca, Ba) composition range. The results indicate that major mineral phases of the aluminosilicate glass-ceramics are Al_(20)B_4O_(36), CaAl_2Si_2O_8, and BaAl_2Si_2O_8 and that the glass-ceramic materials are characterized by dense microstructures and excellent dielectric properties.

关键词： glass-ceramics liquid-phase sintering aluminosilicate mineral phase microstructures

Temperature Gradient Induced Orientation Change of Bi Grains in Sn–Bi57–Ag0.7 Solder Joint

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Acta Metallurgica Sinica(English Letters) 2022年第7期35卷 1184-1194页

作者： Yinbo chen Zhaoqing Gao Zhi-quan Liu Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China School of Materials Science and Engineering Dalian University of TechnologyDalian 116024China Shenzhen Institute of Advanced Electronic Materials Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China

Sn-Bi-X solders are widely used in electronic packaging ***,thermomigration(TM)behaviors of Sn-BiX solder joints and the orientations change of Bi grains under the temperature gradient are rarely *** this study,Sn-Bi57-Ag0.7/Cu solder joints were used to conduct a TM test under a temperature gradient of 625℃/cm for 400 h,and an isothermal aging test at 85℃was also conducted for *** microstructural evolution of Sn-Bi-X solder joints after reflow,TM and isothermal aging were analyzed by scanning electron microscopy(SEM),transmission electron microscopy(TEM)and electron probe microanalysis(EPMA).The results indicated that the Sn/Bi areal ratio after TM did not change significantly whether at the hot end(from 46.78%/52.12%to 50.90%/48.78%)or at the cold end(from 50.25%/49.64%to 48.71%/51.16%)compared with that of as-reflowed samples due to the insufficient thermal *** thickness of intermetallic compound(IMC)after TM at hot end(2.49μm)was very close to that of the IMC at cold end(2.52μm),which was also close to that of the aged *** addition,the preferred orientations of Sn and Bi grains in different Sn–Bi–Ag solder joints resulting from different conditions(reflow,TM and isothermal aging)were characterized by electron backscatter diffraction(EBSD).The obtained results demonstrated that both Sn and Bi grains had no preferred orientation whether after reflowor isothermal aging,while the orientation of Bi grains of the sample after TM changed from random direction to c-axis([0001]direction)parallel to the heat *** 3 Sn could hinder the change of orientation of Bi grains under the temperature gradient,and the corresponding mechanism was also systematically *** study firstly revealed the orientation change of Bi grains under the temperature gradient,which would have a profound guiding significance for enhancing the reliabilities of Sn–Bi–Ag solder joints.

关键词： Sn–Bi–Ag solder Grain orientation Temperature gradient Aging Ag3Sn

Molecular transformation of dissolved organic matter in refinery wastewaters: Characterized by FT-ICR MS coupled with electrospray ionization and atmospheric pressure photoionization

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Petroleum Science 2023年第1期20卷 590-599页

作者： chen He Wei-Ming chen Chun-Mao chen quan Shi State Key Laboratory of Heavy Oil Processing Beijing Key Laboratory of Oil and Gas Pollution ControlChina University of PetroleumBeijing 102249China Faculty of Geosciences and Environmental Engineering Southwest Jiaotong UniversityChengduSichuan 611756China

Dissolved organic matter(DOM)in refinery wastewater is an extremely complex mixture of various organic *** mass spectrometry,it is impossible to characterize all of the DOM molecules with only one ionization *** this study,negative-ion,electrospray ionization(ESI),positive-ion ESI,and positive-ion atmospheric pressure photoionization(APPI)were coupled with Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS)to analyze the molecular composition of DOM in a refinery wastewater stream during the treatment *** were obvious differences in the heteroatom composition,number of DOM constituents,and chemical properties in refinery wastewater under the three ionization *** CHO and CHOS compounds detected by(+)ESI,basic CHN and CHON compounds detected by(þ)ESI,and hydrocarbons detected by(+)APPI were analyzed to determine the molecular transformations that occurred during *** an anaerobic biological treatment process,acidic CHO and CHOS compounds with a high oxygen content were preferentially removed,and acidic CHO and CHOS compounds with a low oxygen content were *** an aerobic biological process,acidic CHO and CHOS compounds with a low oxygen content were preferentially removed,and acidic CHO and CHOS compounds with a high oxygen content were *** whole biological treatment process has a poor removal efficiency for CHN and CHON compounds,and *** activated carbon(AC)adsorption process removed different heteroatom compounds mainly with a low oxygen content for acidic and basic *** transformation mechanism of CHO and CHOS compounds in the biological treatment process was analyzed by the Kendrick mass defect(KMD)theory and a mass difference network *** the anaerobic process,large amounts of oxygenated CHO and CHOS compounds were degraded by decarboxylation,deoxydation,demethoxylation,and dehydration reactions,and converted to lower oxygen content *** the aerobic

关键词： Refinery wastewater DOM Molecular transformation ESI APPI FT-ICR MS

Numerical simulation study on penetration performance of depleted Uranium(DU)alloy fragments

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Defence Technology（防务技术） 2021年第1期17卷 50-55页

作者： Fu-lin Zhu Yang chen gui-li Zhu Sichuan Aerospace System Engineering Institute Chengdu610100SichuanChina

Due to its high strength,high density,high hardness and good penetration capabilities,Depleted uranium alloys have already shined in armor-piercing *** should also be a lot of room for improvement in the application of fragment killing ***,regarding the performance of the depleted uranium alloy to penetrate the target plate,further investigation is needed to analyze its advantages and disadvantages compared to tungsten *** study the difference in penetration performance between depleted uranium alloy and tungsten alloy fragments,firstly,a theoretical analysis of the adiabatic shear sensitivity of DU and tungsten alloys was given from the perspective of material constitutive ***,taking the cylindrical fragment penetration target as the research object,the penetration process and velocity characteristics of the steel target plates penetrated by DU alloy fragment and tungsten alloy fragment were compared and analyzed,by using finite element software ANSYS/LS-DYNA and Lagrange ***,the influence of different postures when impacting target and different fragment shapes on the penetration results is carried out in the *** results show that in the penetration process of the DU and tungsten alloy fragments,the self-sharpening properties of the DU alloy can make the fragment head sharper and the penetrating ability *** the same conditions,the penetration capability of cylindrical fragment impacting target in vertical posture is better than that in horizontal posture,and the penetration capability of the spherical fragment is slightly better than that of cylindrical fragment.

关键词： Depleted uranium alloy Constitutive model Adiabatic shear Penetration performance Numerical simulation