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International Conference on Transportation engineering

作者： Liu, Hanru Wei, Jinjia State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an China Xi'An Jiaotong University Xi'an 710049 China

ISBN: (纸本)9780784411841

As the speed of high-speed train (HST) increases continuously, aerodynamic noise has become more important compared with the wheel/rail noise, which affects the inhabited environment around the railway and the comfort of passengers. This paper preliminarily investigates the feasibility of reducing the low Mach number aerodynamic noise by using ultra-light porous metals. The noise generated by the flow around a two-dimensional circular cylinder which is the typical unit of pantographs, was simulated with and without a porous media. The hybrid method that combines large eddy simulation (LES) with Ffowcs Williams-Hawkings (FW-H) equation was employed. The calculated overall sound pressure level (OASPL), vortex shedding frequency and time-average drag coefficient agree well with available experimental data. Then, the effects of porosity and the speed of train on the aerodynamic noise were predicted and explained in view of fluid mechanics. The numerical results indicate that the open cell-type porous media with high porosity can modify and regularize the fluid flow, adjust the vortex shedding frequency, leading to a significant reduction of aerodynamic noise. © 2011 ASCE.

关键词： Porous materials

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Experiment of flow boiling heat transfer on micro-pin-finned chips with jet impingement

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Hsi-An Chiao Tung Ta Hsueh/Journal of Xi'an Jiaotong University 2011年第1期45卷 31-37页

作者： Guo, Dong Wei, Jinjia Zhang, Yonghai State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The experiment of flow boiling heat transfer on micro-pin-finned chips in FC-72 with jet impingement was *** experimental conditions consisted of two different liquid subcooling degrees (25,35°C),three different cross flow velocities (Vc=0.5,1,1.5 m/s) and three different jet velocities (Vj=0,1,2 m/s).The dimensions of the silicon chips were 10 mm×10 mm×0.5 mm (length×width×thickness) on which two kinds of micro-pin-fins with the dimensions of 30 μm×120 μm,50 μm×120 μm (thickness×height) were fabricated by the dry etching technique. A smooth surface was also tested for comparison. The correlations for nucleate boiling curves and the maximum allowable heat flux curves were obtained. The results show that the heat transfer performance was improved with increasing liquid subcooling and flow velocity. All micro-pin-finned surfaces displayed a considerable heat transfer enhancement. The addition of jet impingement further enhanced the heat transfer at a high heat flux and increased the CHF. At a certain cross flow velocity, the enhancement was more significant as the jet velocity increased, especially for Vc=0.5 m/s, Vj=2 m/s. For the micro-pin-finned chips, the CHF increased by more than 93% while the subcooling was 35°C compared with Vc=0.5 m/s, Vj=0 m/s. As the cross velocity increased, the intensification degree of jet impingement decreased and the increase of CHF also decreased.

关键词： flow velocity

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Kinetic study of the isomerization for endo-tetrahydrodicyclopentadiene over AlCl3 catalyst

Kinetic study of the isomerization for endo-tetrahydrodicycl...

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2011 2nd International Conference on Mechanic Automation and Control engineering, MACE 2011

作者： Hao, Miaoli Wu, Weitao Qi, Suitao Yang, Bolun Yang, Jianming Zhang, Wei Lv, Jian Department of Chemical Engineering State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China Xi'an Modern Chemistry Research Institute Xi'an China

ISBN: (纸本)9781424494392

The isomerization of endo-tetrahydrodicyclopentadiene (THDCPD) to exo-THDCPD over AlCl3 catalyst has been studied in a batch reactor. The effects of temperature, catalyst loading, and the type and amount of solvent on the isomerization rate were investigated. Under the conditions of removing both internal and external diffusion effects, a kinetic model was established and the model parameters were developed. The results showed that the endo- to exo- isomerization of THDCPD can be treated as a first-order reaction. The activation energy E0 and pre-exponential factor obtained from Arrhenius plot are 116 kJ /mol and 3.39×1013 respectively. The simulation results agreed well with the experimental data. © 2011 IEEE.

关键词： Isomerization

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Supersonic ejector to boost production from low pressure natural gas field

Supersonic ejector to boost production from low pressure nat...

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International Conference on Computer Distributed Control and Intelligent Environmental Monitoring

作者： Wu, Gesheng Chong, Daotong Chen, Weixiong Yan, Junjie State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum University Chendu China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

ISBN: (纸本)9780769543505

An effective way to boost natural gas production from low pressure gas field was introduced in the paper. The supersonic ejector used the energ off high pressure gas wells, which was generally wasted through the choke valve, as its power supply to boost the low pressure gas production. The field experiment of the natural gas ejector was carried out, and the performance of the ejector was also presented. Moreover, the production of low pressure natural gas well was compared when the natural gas ejector was used or not. The economic analysis shows that the recovery period of the capital was less than several months. © 2011 IEEE.

关键词： Natural gas

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Performance enhancement for nanofluid-cooled microchannel heat sink

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Yingyong Jichu yu Gongcheng Kexue Xuebao/Journal of Basic Science and engineering 2012年第SUPPL.期20卷 169-180页

作者： Lin, Lin Wang, Xiaodong Wang, Zhenhua Department of Thermal Engineering University of Science and Technology Beijing Beijing 100083 China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing 102206 China Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy North China Electric Power University Beijing 102206 China Xi'an Shaangu Power Co. LTD Xi'an 710075 China

Based on selecting the proper formulas of thermal conductivity and viscosity for nanofluids, a three-dimensional fluid-solid conjugated model was developed to analyze the effect of the heat sink structure, the nanoparticle kind, diameter and volume fraction, and the base fluid kind on the cooling performance of microchannel heat sink. The results showed that: (1) thermal dispersion effect caused by nanoparticle random motion enhanced the thermal convection of nanofluid thus enhances significantly the cooling performance of heat sink;(2) the enhancement of nanofluids was closely dependent on the heat sink structure and the dependence was distinct from the pure fluid, hence the heat sink structure was needed to be optimized for nanofluids as coolants;(3) as the nanoparticle volume fraction increases, the thermal resistance reduced and the pressure increased, the water-based Al2O3 nanofluid with 0.5% volume fraction was the optimal coolant which caused 10.1% decrease in the thermal resistance and only 0.38% increased in the pressure drop;(4) although the nanoparticle size had a small effect on the thermal resistance, nanoparticles with small diameter were recommended with consideration of stability of nanofluids;(5) Al2O3 nanoparticle was superior to TiO2 and CuO, and water was the better base fluid than ethylene glycol and engine oil.

关键词： Nanoparticles

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MPS simulation of primary thrombus formation in capillary

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2011年第2期32卷 227-229页

作者： Rong, Shao-Shan Chen, Bin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The adhesion, activation and aggregation of platelets play an important role in the primary thrombus formation. In present paper, platelets, plasma, normal and injured endodermis of the vessel are modeled as particles with different characteristics and simulated by the Moving Particle Semi-implicit (MPS) method. In order to simulate the aggregation and adhesion of platelets on the injured endodermis of the vessel, a mechanical adhesion force model is introduced according to the inter-molecular force and physiological interaction between platelets and endodermis is modeled by the stretch and rotation of a spring. By this method, the formation of primary thrombus at the injured endodermis of horizontal and bending vessel is numerically reproduced. Results show that the thrombus forms quickly and the number of adhered platelets will not increase if thrombus has been formed. Through the analysis of flow field, the platelets go through the vibration, steady and potential break free process. Compared with horizontal vessel, the thrombus formation at the bending vessel is slower.

关键词： Platelets

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Performance comparison and analysis of typical energy conversion cycle

Performance comparison and analysis of typical energy conver...

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International Conference on Computer Distributed Control and Intelligent Environmental Monitoring

作者： Wang, Yuqi Zheng, Lan Yang, Fusheng Meng, Xiangyu Zhang, Zaoxiao School of Chemical Engineering Northwest University Xi'an Shaanxi 710069 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an Shaanxi 710049 China

ISBN: (纸本)9780769543505

The performance of 3 types of energy utilization cycles including the organic Rankine cycle, the single stage static hydrogen compression cycle, and the new multistage continuous hydrogen compression cycle were analyzed. A multi-element valued model was used to evaluate the performance holistically, and the result showed that the integrated superiority achieved 0.721, which indicated the continuous hydrogen compression cycle is considered the best option among the typical compression energy utilization cycles and deserves thorough studying. © 2011 IEEE.

关键词： Energy utilization

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Numerical simulation of bubble induced flow by vortex method

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AIP Conference Proceedings 2011年第1期1376卷 591-593页

作者： Z. W. Wang T. Uchiyama B. Chen aState Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China bEcoTopia Science Institute Nagoya University Nagoya 464‐8603 Japan

The behavior of air bubbles rising in water and the bubble induced flow field are numerically studied using a three‐dimensional two‐way coupling algorithm based on Vortex‐In‐Cell method. A small vortex ring structure is generated with the rising of bubbles and the small vortex ring structure is led by the rising bubble cluster at first. The bubbles are accelerated by the vortex ring structure, and the bubble distribution and the shape of the bubble cluster are transformed by the vortex ring structure at the same time.

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Anomalous enhancement in thermal conductivity of nanofluid induced by solid walls in a nanochannel

Anomalous enhancement in thermal conductivity of nanofluid i...

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作者： Sun, Chengzhen Lu, Wen-Qiang Bai, Bofeng Liu, Jie State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an 710049 China College of Physical Sciences Graduate University Chinese Academy of Sciences Beijing 100049 China

Thermal conductivity of Ar-Cu nanofluid confined between two parallel walls (in a nanochannel) is calculated by equilibrium-molecular-dynamics (EMD) simulation through Green-Kubo formula. The results show that the vibration of nanoparticle in the channel height direction (z-direction) is inhibited due to the presence of solid boundaries and accordingly the thermal conductivity of the confined nanofluid is obviously anisotropic. Anomalous enhancement in the thermal conductivity perpendicular to the z-direction (λ) appears as a result of the strong coupling interactions between the fluid atoms, especially the nanoparticle atoms, and the wall atoms. The thermal conductivity λ of the nanofluid confined in the channel of width h = 5.148 nm increases with the increase of the nanoparticle diameter for the strengthened couplings. The nanoparticle volume fraction effect on the thermal conductivity of the confined nanofluid is more obvious than that in macroscale. In addition, the thermal conductivity λ of the nanofluid with diameter of nanoparticle d = 1.370 nm decreases with the channel width increasing owing to the weakened couplings resulted by a longer interacting distance. © 2011 Elsevier Ltd. All rights reserved.

关键词： Molecular dynamics

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Enhancing Photocurrent in Unannealed NiS x /CdS Photoelectrochemical System for Water Splitting and Hydrogen Production

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MRS Online Proceedings Library 2011年第1期1326卷 1-6页

作者： Ning Zhang Liejin Guo State Key Laboratory of Multiphase Flow in Power Engineering (MPFL) School of Energy and Power Engineering Xi’an Jiaotong University Shaanxi PR China

In this work, NiSx was deposited on FTO by chemical bath and worked as the inner layer in order to enhance the photocurrent of CdS film. It is found the unannealed CdS/NiSx had a higher photocurrent than unannealed CdS, but after annealing, the photocurrent of CdS/NiSx showed dramatical decrease. The mechanism was discussed in detail by UPS and current-potential curves.

关键词： Ni S thin film

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