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Assessment on the Long Term Performance of a LaNi 5 based Hydrogen Storage System

Energy Procedia 2012年 29卷 720-730页

作者： Fusheng Yang Xinxin Cao Zaoxiao Zhang Zewei Bao Zhen Wu Nyallang Nyamsi Serge State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 P. R.China Suzhou Research Institute Xi’an Jiaotong University Suzhou 215123 P. R. China

Metal hydride represents a promising candidate for hydrogen storage, because the technique is essentially safe, compact and flexible. However, the properties of the metal hydride tend to change in repeated hydriding/dehydriding cycles, which will inevitably affect the performance of corresponding hydrogen storage system. The effect is investigated in this paper by numerical simulation using a commercial package COMSOL MULTIPHYSICS 3.5a, and a typical material- LaNi5 is chosen for discussion. Through sensitivity analysis, the influences of variation in key properties over repeated cycles on the charging time of a tank-type storage system, are evaluated and some useful conclusions are drawn.

关键词： Metal hydride Hydrogen storage system Hydriding/dehydriding cycles Charging time Reaction kinetics

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Coupling lattice Boltzmann model for simulation of thermal flows on standard lattices

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Physical Review E 2012年第1期85卷 016710-016710页

作者： Q. Li K. H. Luo Y. L. He Y. J. Gao W. Q. Tao Key Laboratory of Thermal Fluid Science and Engineering of MOE National Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an Shaanxi 710049 China Energy Technology Research Group School of Engineering Sciences University of Southampton Southampton SO17 1BJ United Kingdom Center for Combustion Energy Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Thermal Engineering Tsinghua University Beijing 100084 China Department of Zoology University of Cambridge Cambridge CB2 3EJ United Kingdom

In this paper, a coupling lattice Boltzmann (LB) model for simulating thermal flows on the standard two-dimensional nine-velocity (D2Q9) lattice is developed in the framework of the double-distribution-function (DDF) approach in which the viscous heat dissipation and compression work are considered. In the model, a density distribution function is used to simulate the flow field, while a total energy distribution function is employed to simulate the temperature field. The discrete equilibrium density and total energy distribution functions are obtained from the Hermite expansions of the corresponding continuous equilibrium distribution functions. The pressure given by the equation of state of perfect gases is recovered in the macroscopic momentum and energy equations. The coupling between the momentum and energy transports makes the model applicable for general thermal flows such as non-Boussinesq flows, while the existing DDF LB models on standard lattices are usually limited to Boussinesq flows in which the temperature variation is small. Meanwhile, the simple structure and general features of the DDF LB approach are retained. The model is tested by numerical simulations of thermal Couette flow, attenuation-driven acoustic streaming, and natural convection in a square cavity with small and large temperature differences. The numerical results are found to be in good agreement with the analytical solutions and/or other numerical results reported in the literature.

关键词： LATTICE Boltzmann methods MATHEMATICAL models COMPUTER simulation THERMAL analysis ENERGY dissipation DISTRIBUTION (Probability theory) ACOUSTIC streaming DENSITY functionals

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Experimental and kinetic study on ignition delay times of methane/hydrogen/oxygen/nitrogen mixtures by shock tube

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Chinese Science Bulletin 2011年第26期56卷 2853-2861页

作者： ZHANG YingJia HUANG ZuoHua WEI LiangJie NIU ShaoDong State Key Laboratory of Multiphase Flow in Power Engineering Xi' an Jiaotong University Xi'an 710049 China

Ignition delay times of methane/hydrogen/oxygen/nitrogen mixtures with hydrogen amount-of-substance fractions ranging from 0–20% were measured in a shock tube *** ambient temperature varied from 1.22 to 1.77 K and the pressure was maintained at 0.4 MPa behind the reflected shock *** experiments were conducted at an equivalence ratio of *** fuel mixtures were diluted with nitrogen gas so that the nitrogen amount-of-substance fraction was 95%.The experimental ignition delay time of the CH4/H2 mixture decreased as the hydrogen amount-of-substance fraction *** enhancement of ignition by hydrogen addition was weak when the ambient temperature was >1.50 K,and strong when the temperature was <1.25 *** ignition delay time of 20% H2/80% CH4 was only one-third that of 1.0% CH4 at 1.00 K.A modified model based on GRI-Mech 3.0 was proposed and used to calculate the ignition delay times of test *** calculated results agreed with the experimental ignition delay *** sensitivity analysis showed that HO·+H2 →H·+H2O was the main reaction for the formation of the H· at 1.00 *** the hydrogen amount-of-substance fraction increased,chain branching was enhanced through the reaction H·+O2→O·+HO·,and this reduced the ignition delay *** 1.00 K,the methyl radical (H3C·) became the key species that influenced the ignition of the CH4/H2/O2/N2 mixtures,and sensitivity coefficients of the chain termination reaction 2H3C·(+M)→C2H6(+M),and chain propagation reaction HO2+H3C·→HO·+CH3O decreased,which reduced the influence of hydrogen addition on the ignition of the CH4/H2 mixtures.

关键词：点火延迟时间混合物动力学激波管氢气实验氮气甲烷

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Additional interfacial force in lattice Boltzmann models for incompressible multiphase {1.s

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Physical Review E 2012年第2期85卷 026704-026704页

作者： Q. Li K. H. Luo Y. J. Gao Y. L. He Energy Technology Research Group School of Engineering Sciences University of Southampton Southampton SO17 1BJ United Kingdom Center for Combustion Energy Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Thermal Engineering Tsinghua University Beijing 100084 China Department of Zoology University of Cambridge Cambridge CB2 3EJ United Kingdom National Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

The existing lattice Boltzmann models for incompressible multiphase {1.s are mostly constructed with two distribution functions: one is the order parameter distribution function, which is used to track the interface between different phases, and the other is the pressure distribution function for solving the velocity field. In this paper, it is shown that in these models the recovered momentum equation is inconsistent with the target one: an additional force is included in the recovered momentum equation. The additional force has the following features. First, it is proportional to the macroscopic velocity. Second, it is zero in every single-phase region but is nonzero in the interface. Therefore it can be interpreted as an interfacial force. To investigate the effects of the additional interfacial force, numerical simulations are carried out for the problem of Rayleigh-Taylor instability, droplet splashing on a thin liquid film, and the evolution of a falling droplet under gravity. Numerical results demonstrate that, with the increase of the velocity or the Reynolds number, the additional interfacial force will gradually have an important influence on the interface and affect the numerical accuracy.

关键词： COMPUTER simulation LATTICE Boltzmann methods multiphase {1. INCOMPRESSIBLE flow (Fluid mechanics) DISTRIBUTION (Probability theory) MOMENTUM (Mechanics)

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Enhanced Heat Transfer of flow Boiling Combined with Jet Impingement

Enhanced Heat Transfer of Flow Boiling Combined with Jet Imp...

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第七届天地应用两相系统国际研讨会

作者： J.J.Wei J.F.Zhao D.Guo Y.H.Zhang State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University28 Xianning XiluXi’an 710049China 2National Microgravity LaboratoryInstitute of MechanicsChinese Academy of Sciences 15 Beisihuan XiluBeijing 100190China

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Combustion and emission characteristics of a turbo-charged common rail diesel engine fuelled with diesel-biodiesel-DEE blends

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能源前沿 2011年第1期5卷 104-114页

作者： Ni ZHANG Zuohua HUANG Xiangang WANG Bin ZHENG State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049China

The combustion and emission characteristics of a turbo-charged, common rail diesel engine fuelled with diesel-biodiesel-DEE blends were investigated. The study repons that the brake-specific fuel consumption of dieselbiodiesel-DEE blends increases with increase of oxygenated fuel fractions in the blends. Brake thermal efficiency shows little variation when operating on different dieselbiodiesel-DEE blends. At a low load, the NOx emission of the diesel-biodiesel-DEE blends exhibits little variation in comparison with the biodiesel fraction. The NOx emission slightly increases with increase in the biodiesel fraction in diesel-biodiesel-DEE blends at medium load. However,the NOx emission increases remarkably with increase of the biodiesel fraction at high load. Particle mass concentration decreases significantly with increase of the oxygenated-fuels fraction at all engine speeds and loads;particle number concentration decreases remarkably with increase of the oxygenated-fuels fraction. HC and CO emissions decrease with increasing oxygenated-fuels fraction in these blends.

关键词： Combustion particulate emissions dieselbiodiesel-DEE blend diesel engine

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Influence of cetane number improver on performance and emissions of a common-rail diesel engine fueled with biodiesel-methanol blend

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能源前沿 2011年第4期5卷 412-418页

作者： Wu YU Gen CHEN Zuohua HUANG State Key Laboratory of Multiphase Flow in Power Engineering Xi'anJiaotong University Xi'an 710049 China

In this paper,the effect ofcetane number (CN)improver on performance and emissions,including particulate number concentration and size distribution,of a turbocharged,common-rail diesel engine fueled with biodiesel-methanol were *** volume fractions (0.3％ and 0.6％) of CN improver were added to BM30 (30％ of methanol in the biodiesel-methanol blend) in the *** results show that,compared with those of biodiesel-methanol blend,the peak value of cylinder pressure increases,the second peak of heat release rate decreases,the start of second heat release are advanced,and the fuel economy and thermal efficiency are improved when CN improver is added to biodiesel-methanol ***,CO and HC emissions decrease,NOx emission varies little and smoke emissions increase ***,exhaust particles of BM30 mainly distribute in nanosize ***,particle number concentration decreases and peak of size distribution profile shifts toward large size direction.

关键词： biodiesel methanol common-rail (CR) dieselengine cetane number (CN) improver

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Numerical simulation of the heat flux distribution in a solar cavity receiver

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能源前沿 2011年第1期5卷 98-103页

作者： Yueshe WANG Xunwei DONG Jinjia WEI Hui JIN State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

In the solar tower power plant, the receiver is one of the main components of efficient concentrating solar collector systems. In the design of the receiver, the heat flux distribution in the cavity should be considered first. In this study, a numerical simulation using the Monte Carlo Method has been conducted on the heat flux distribution in the cavity receiver, which consists of six lateral faces and floor and roof planes, with an aperture of 2.0m×2.0m on the front face. The mathematics and physical models of a single solar ray's launching,reflection, and absorption were proposed. By tracing every solar ray, the distribution of heat flux density in the cavity receiver was obtained. The numerical results show that the solar flux distribution on the absorbing panels is similar to that of CESA-I's. When the reradiation from walls was considered, the detailed heat flux distributions were issued, in which 49.1.% of the total incident energy was absorbed by the central panels,47.02% by the side panels, and 3.88% was over{1.ed from the aperture. Regarding the peak heat flux, the value of up to 1.96.406 kW/m2 was obtained in the center of absorbing panels. These results provide necessary data for the structure design of cavity receiver and the local thermal stress analysis for boiling and superheated panels.

关键词： solar cavity receiver Monte Carlo method heat flux distribution

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Bubble Behavior and Heat Transfer of Nucleate Pool Boiling on Micro-Pin-Finned Surface in Microgravity

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Chinese Physics Letters 2011年第1期28卷 160-163页

作者： WEI Jin-Jia XUE Yan-Fang ZHAO Jian-Fu LI Jing State Key Laboratory of Multiphase Flow in Power Engineering Xi 'an Jiaotong University Xi'an 710049 Key Laboratory of Microgravity (National Microgravity Laboratory)/CAS Institute of Mechanics Chinese Academy of Sciences Heijing 100190

Nucleate pool boiling on micro-pin-finned surface structure is proposed for efficiently cooling electronic compo- nents with high heat flux in microgravity, and was verified by experiments performed utilizing the drop tower Beijing. Micro-pin-fins with tile dimensions of 50 × （30 μm2 （thickness × height） and the space of 50 μm were fabricated on the chip surface by the dry etching technique. FC-72 was used as the working fluid. Nucleate pool boiling of FC-72 on a smooth surface was also tested for comparison. Unlike much obvious deterioration of heat transfer of nucleate pool boiling on the smooth surface in microgravity, constant heater surface temperature of nucleate pool boiling for the micro-pin-finned surface was observed, even though a large coalesced bubble completely covered the surface under microgravity condition. The performance of high efficient heat transfer on micro-pin-finned surface is independent of the gravity, which stems from the sufficient supply of fresh liquid to the heater surface due to the capillary forces.

关键词： Fluid dynamics Surfaces, interfaces and thin films

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Preparation and Photocatalytic Activities of Magnetic TiO2/Fe3O4 Composite Nanoparticles

Preparation and Photocatalytic Activities of Magnetic TiO2/F...

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UK-China Symposium of New Energy Materials and Nanotechnology(201.年中英纳米技术和新能源材料研讨会)

作者： SU Jie CHENG Wen MA Xia LIU Rui LI Huiqiang YAN Yanli Xi''an University of Technology Xi''an 710048China Xi''an 710049 China Key Laboratory of Northwest Water Resources Environment and Ecology Ministry of Education State Key Laboratory of Multiphase Flow in Power Engineering Xi''an Jiao tong University Xi''an University of Technology Xi''an 710048China Key Laboratory of Northwest Water ResourcesEnvironment and Ecology Ministry of Education

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