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Study on the characteristics of flowing organization in DMFC. Part I: Model development of cell with conventional symmetrical plates

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Taiyangneng Xuebao/Acta Energiae Solaris Sinica 2008年第9期29卷 1155-1160页

作者： Yin, Benhao He, Yaling Li, Xianglin Miao, Zheng State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

A two-dimensional, steady-state model of a direct methanol fuel cell (DMFC) with liquid methanol feed was developed. The electrode kinetics, multi-component transport and methanol crossover phenomenon were all considered. The effect of channels disposal density, the influence of backing layer, catalyst layer and polymer electrolyte membrane thickness on mass transfer and cell performance was investigated. The results showed that: with the increase of channels disposal density and the increase of catalyst layer thickness, the equality of reaction rate and cell performance will elevated. The sizes of catalyst layer and membrane effect farthest, the correspondingly optimized work can increase the average current density about 131.0% and 17.8%. There are moderate optimal thickness sizes of backing layer and membrane, and the sizes should be chosen after thinking about the sizes of flow field plate and MEA.

关键词： Methanol

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Measurement of diffusion coefficient using Michelson interferometry

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Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument 2008年第SUPPL. 2期29卷 488-492页

作者： Guo, Ying He, Maogang Zhang, Ying Zhong, Qiu State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

In this paper, an experimental system for the measurement of mass diffusion coefficient using Michelson laser holographic Interferometry was designed and constructed. The experimental system include: the subsystem of Michelson interferometer, the diffusion cell for the mass diffusion of liquid-liquid, the subsystem of thermostatic water bath, the subsystem of image collecting and image processing. The mass diffusion coefficients of 0.33 molL-1 KCI solution with water at the temperature of 289.15 K were measured, and the result shows that the average of relative deviations is 1.30% compared with the literature values, and it verified the accuracy and reliability of the system. The mass diffusion coefficients of 0.1 molL-1 saccharose with water at 5 different temperature were measured, and the result shows that the biggest relative deviations is within 5% which verified the reliability of the system further.

关键词： Michelson interferometers

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Bactericidal Action of the Reactive Species Produced by Gas-Discharge Nonthermal Plasma at Low Pressure

Bactericidal Action of the Reactive Species Produced by Gas-...

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9th Asia-Pacific Conference on Plasma Science and Technology (APCPST) and 21st Symposium on Plasma Science for Materials (SPSM)第9届亚太等离子体科学与技术国际会议暨第21届等离子体材料科学研讨会

作者： H.X.Liu J.R.Chen J.L.Zhao Department of Environmental Science and Engineering Xi''an Jiaotong University Xi''an.710049.China State Key Laboratory of Multiphase Flow in Power Engineering Xi''an Jiaotong University Xi''an.710049.China Department of Environmental Science and Engineering Xi''an Jiaotong University Xi''an.710049.China

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Experimental research on catalysts and their catalytic mechanism for hydrogen production by gasification of peanut shell in supercritical water

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中国高等学校学术文摘·能源与动力工程 2007年第4期1卷 451-456页

作者： PEI Aixia GUO Liejin JIN Hui State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

Peanut shell,mixed with sodium carboxymethylcellulose,was gasified at a temperature of 450℃ and a pressure range from 24 to 27 MPa with the presence of different catalysts,including K2CO3,ZnCl2 and *** experimental results show that different catalysts have greatly different effects on the *** efficiency (GE),hydrogen gasification efficiency (GHE),carbon gasification efficiency (GCE),yield of hydrogen production (YH2) and potential yield of hydrogen production (YPH2) are applied to describe the catalytic *** the result of gaseous components,ZnCl2 has the highest hydrogen selectivity,K2CO3 is lower,and Raney-Ni is the lowest,but Raney-Ni is the most favorable to gasify biomass among the three catalysts,and its GE,GHE,GcE reach 126.84%,185.71%,94.24%,*** expected,hydrogen selectivity increased and CH4 reduced rapidly when the mixture of ZnCl2 and Raney-Ni is used under the same *** optimization mixture appeared when 0.2 g of ZnCl2 was added to 1 g of Raney-Ni,43.56 g·kg-1 of hydrogen production was *** addition,the catalytic mechanisms of different catalysts were analyzed,and the possible reaction pathway was brought forward,which helped to explain the experiment phenomena and results correctly.

关键词： biomass supercritical water gasification,hydrogen production

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Estimation of thermodynamic properties of the ternary molten salt system, LiF-NaF-BeF2, by the modified Peng-Robinson equation

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中国高等学校学术文摘·能源与动力工程 2007年第2期1卷 174-180页

作者： ZHANG Dalin QIU Suizheng SU Guanghui JIA Dounan School of Energy and Power Engineering State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The molten salt reactor (MSR), which is one of the generation IV reactors, can meet the demand of transmutation and breeding. The thermodynamic properties of the molten salt system like LiF-NaF-BeF2 influence the design and construction of the fuel salt and coolant in the MSR for the new generation. In this paper, the equation of state of the ternary system 15%LiF-58%NaF-27%BeF2, over the temperature range from 873.15 to 1 073.15 K at one atmosphere pressure, is described using a modified Peng-Robinson (PR) equation. The densities of the ternary system and its components are estimated by this equation directly, and compared with the experimental data. Based on the equation of state, the other thermodynamic properties such as the enthalpy, entropyand heat capacity at constant pressure are estimated by the residual function method and the fugacity coefficient method respectively. The densities calculated by PR equation are highly in agr eement with the experimental data, and the enthalpy, entropy and heat capacity evaluated by the two different methods are consistent with each other. It can be concluded that the modified PR equation can be applied to evaluate the density of the molten salt system, and it is recommended that it be used as the basis to estimate the enthalpy, entropy and heat capacity of the molten salt system.

关键词： thermodynamic properties molten salt LiF-NaF-BeF2 Peng-Robinson equation

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An investigation into the heat transfer characteristics of spiral wall with internal rib in a supercritical sliding-pressure operation once-through boiler

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中国高等学校学术文摘·能源与动力工程 2007年第3期1卷 300-304页

作者： TANG Renhu YIN Fei WANG Haijun CHEN Tingkuan The State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

Within the pressure range of 9-28 MPa,mass 200-500 kW/m2,experiments were performed to investigate the heat transfer to water in the inclined upward internally ribbed tube with an inclined angle of 19.5 degrees,a maximum outer diameter of 38.1 mm,and a thickness of 7.5 *** on the experiments,it was found that heat transfer enhancement of the internally ribbed tube could postpone departure from nucleate boiling at the sub-critical ***,the heat transfer enhancement decreased near the critical *** supercritical pressure,the temperature difference between the wall and the fluid increased near the pseudo-critical temperature,but the increase of wall temperature was less than that of departure from nucleate boiling at sub-critical *** pressure is closer to the critical pressure,the temperature difference between the wall and the fluid increased greatly near the pseudo-critical *** transfer to supercritical water in the inclined upward internally ribbed tube was enhanced or deteriorated near the pseudo-critical temperature with the variety of ratio between the mass velocity and the heat *** the rotational flow of the internal groove reduced the effect of natural convection,the internal wall temperature of internally ribbed tube uniformly distributed along the *** maximum internal wall temperature difference of the tube along the circumference was only 10 degrees when the fluid enthalpy exceeded 2 000 J/*** the effect of acute variety of the fluid property on heat transfer,the correlation of heat transfer coefficient on the top of the internally ribbed tube was orovided.

关键词： thermal power engineering heat transfer supercritical pressure boiler internally ribbed tube departure from nucleate boiling

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Simulation of horizontal slug-flow pneumatic conveying with kinetic theory

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中国高等学校学术文摘·能源与动力工程 2007年第3期1卷 336-340页

作者： GU Zhengmeng GUO Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

Wavelike slug-flow is a representative flow type in horizontal pneumatic *** theory was introduced to establish a 3D kinetic numerical model for wavelike slug gas-solid flow in this *** motion of particulate slugs in horizontal pipes was numerically *** formation and motion process of slugs and settled layer were *** characteristics of the flow,such as pressure drop,air velocity distribution,slug length and settled layer thickness,and the detailed changing characteristics of slug length and settled layer thickness with air velocity were *** results indicate that kinetic theory can represent the physical characteristics of the non-suspension dense phase flow of wavelike slug pneumatic *** experiment in this paper introduced a new idea for the numerical calculation of slug-flow pneumatic conveying.

关键词： slug-flow pneumatic conveying kinetic theory simulation

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Experimental Study of Drop Deformation and Breakup in Simple Shear flows

引用

Chinese Journal of Chemical engineering 2007年第1期15卷 1-5页

作者：林长志郭烈锦 State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University

The experimental results of the deformation and breakup of a single drop immersed in a Newtonian liq-uid and subjected to a constant shear rate which generated by counter rotating Couette apparatus were presented in this paper. From experimental observations, the breakup occurred by three mechanisms, namely, necking, end pinching, and capillary instability. Quantitative results for the deformation and breakup of drop are presented. The maximum diameter and Sauter mean diameter of daughter drops and capillary thread radius are linearly related to the inverse shear rate and independent of the initial drop size, the dimensionless wavelength which is the wave-length divided by the thread width at breakup is independent of the shear rate and initial drop size, and the deforma-tion of threads follows a pseudo-affine deformation for Cai/Cac larger than 2.

关键词： drop deformation breakup Couette shear flow

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Numerical analysis on heat transfer enhancement by longitudinal vortex based on field synergy principle

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中国高等学校学术文摘·能源与动力工程 2007年第3期1卷 365-369页

作者： WU Junmei TAO Wenquan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China School of Environment and Chemical Engineering Xi'an Polytechnic UniversityXi'an 710048China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

Three-dimensional numerical simulation results are presented for a fin-and-tube heat transfer surface with vortex *** effects of the Reynolds number (from 800 to 2 000) and the attack angle (30° and 45°) of a delta winglet vortex generator are *** numerical results are analyzed on the basis of the field synergy principle to explain the inherent mechanism of heat transfer enhancement by longitudinal *** secondary flow generated by the vortex generators causes the reduction of the intersection angle between the velocity and fluid temperature *** addition,the computational evaluations indicate that the heat transfer enhancement of delta winglet pairs for an aligned tube bank fin-and-tube surface is more significant than that for a staggered tube bank fin-and-tube *** heat transfer enhancement of the delta winglet pairs with an attack angle of 45° is larger than that with an angle of 30°.The delta winglet pair with an attack angle of 45° leads to an increase in pressure drop,while the delta winglet pair with the 30°angle results in a slight *** heat transfer enhancement under identical pumping power condition for the attack angle of 30° is larger than that for the attack angle of 45°either for staggered or for aligned tube bank arrangement.

关键词： longitudinal vortex heat transfer enhancement field synergy principle

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Numerical investigation on the dryout point of annular flow in the upward narrow annuli with bilateral heating

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中国高等学校学术文摘·能源与动力工程 2007年第3期1卷 264-272页

作者： SU Guanghui DUAN Feng QIU Suizheng XIAO Zejun HUANG Yanping State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China National Key Laboratory of Bubble and Natural Circulation Nuclear Power Insitute of ChinaChengdu 610041China

Based on the fundamental conservation principles-the mass,momentum,and energy conservation equtions of liquid films and the momentum conservation equation of vapor core,a theoretical three-fluid model has been developed to predict the dryout point of upward annular flow in vertical narrow annuli with bilateral *** range of the parameters are:pressure from 0.5 to 5.0 MPa;mass flow Through numerically solving the model,the relationships among the parameters of the critical quality (Xc),critical heat flux (QCHF),mass flow rate,system pressure,and the ratio of heat flux on the inner wall of the outer tube to that on the outer wall of the inner tube (qo/qi) are obtained and *** predicted results accurately match with the experimental *** a fixed qo,Xc will increase with the decreases in the gap size and the tube curvature when the dryout point occurs on the outer wall of the inner ***,for a fixed qi,when the dryout point occurs on the inner wall of the outer tube,the parametric trend is *** the dryout point on the inner and outer walls occurs simultaneously,Xc reaches a peak value,and the ratio of qo/qi at this position changes with the gap size and the tube curvature.

关键词： critical heat flux critical quality annular flow dryout numerical simulation

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