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8th US National Combustion Meeting 2013

作者： Li, Qianqian Merchant, Shamel S. Green, William H. Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'n Jiaotong University Xi'an710049 China Department of Chemical Engineering Massachusetts Institute of Technology CambridgeMA02139 United States

ISBN: (纸本)9781627488426

With increasing environmental deterioration and energy demand, studies on new alternative fuels have been attracting more attention. N-pentanol is a five carbon, straight-chain alcohol, which can be produced through natural microbial fermentation and/or engineered microorganisms. It has many advantages over lower carbon alcohols, including higher energy density, lower vapor pressure and better fuel compatibility. In this study, a detailed reaction mechanism of n-pentanol, on the basis of a previously proposed n-butanol mechanism, is generated using the open-source software Reaction Mechanism Generator (RMG). High temperature chemistry of the mechanism was validated against recently published laminar flame speeds and ignition delays. Encouraging results between simulations and experiments were observed under most conditions. Simulations were also conducted using a recently developed n-pentanol oxidation mechanism (NUI model) by Heufer et al. For lean mixtures, the two mechanisms show similar results, while the RMG model yields better predictions for rich mixtures and at an elevated pressure. Reaction pathways and sensitivity analysis reveal the key differences between the two mechanisms in terms of intermediates formed and fuel consumption.

关键词： Alternative fuels

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Experimental study on performance and emissions of diesel/n-pentanol blends on a DI diesel engine

Experimental study on performance and emissions of diesel/n-...

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9th Asia-Pacific Conference on Combustion, ASPACC 2013

作者： Wei, Liangjie Cheung, C.S. Huang, Zuohua Department of Mechanical Engineering Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

In this work, experiments were conducted on a diesel engine fueled with n-pentanol/diesel blends to examine the effect of n-pentanol addition on the engine performance and emissions. Results show that, the addition of n-pentanol to diesel increases the brake specific fuel consumption and has little effect on the brake thermal efficiency. Additionally, the emissions of HC, CO and NOx are slightly increased with the increase of n-pentanol in the fuel blends, however, the particulate matter emission is significantly reduced.

关键词： Brakes

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Stability analysis of a square rod bundle sub-channel in supercritical water reactor

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AIP Conference Proceedings 2013年第1期1547卷 181-189页

作者： Wang Hai-jun You Ting Zhang Lei Gu Hong-fang Luo Yu-shan Bian Ji-lian State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiao tong University Xi'an 710049 China

Extensive investigations on the flow and heat transfer behavior in SCWR fuel assembly have been undertaken worldwide. However, stability analysis of supercritical water in the sub-channels of tight lattices is still lacking. In this paper, the flow stability of a fuel bundle channel with square pitches has been analyzed using commercial CFD code-ANSYS Fluent. Typical dynamic instability of Density Wave Oscillation (DWO) has occurred in heated channel containing fluids at supercritical pressure. A further discussion about the impacts of various operational parameters (e.g. power input, system pressure, mass velocity, inlet temperature, etc) shows that the system becomes more stable as system pressure and/or mass flow rate increases. An increase in inlet temperature also has a stabilizing effect on the system.

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Pool boiling heat transfer on ultra-light porous metal foam surfaces

Pool boiling heat transfer on ultra-light porous metal foam ...

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2013 International Conference on Materials for Renewable Energy and Environment, ICMREE 2013

作者： Ji, Xianbing Xue, Qiang Xu, Jiliang Xu, Jia State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing China Beijing Key Laboratory of Multiphase Flow and Heat Transfer North China Electric Power University Beijing China

ISBN: (纸本)9781479933365

Experiments were conducted to study pool boiling heat transfer on ultra-light porous metal foam surfaces, with deionized water as working fluid. The metal foams have pore densities from 30 to 60ppi (pores per inch) and thickness from 2.0 to 5.0mm. The effects of heat flux, surface superheat, liquid temperature and characteristic parameters of metal foam on pool boiling heat transfer were investigated. It is found that metal foam surfaces can significantly enhance pool boiling heat transfer and lower the surface superheat at the boiling incipience. Pore density and thickness exists an optimal value to strengthen boiling heat transfer. The boiling heat transfer coefficient on the metal foam surfaces is about 2∼3 times of those on the plain surfaces. The significant reasons are due to the distinct nature of high porosity and multi-scale pore sizes of metal foams. The larger pores help to release the created vapor while the smaller pores help to suck the liquid toward the heater surface, decreasing the shear stress at the vapor-liquid interface for the counter-current flow. © 2013 IEEE.

关键词： Heat transfer

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Numerical simulation of the multi-component slurry gasification with the non-premixed combustion model

Numerical simulation of the multi-component slurry gasificat...

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2013 Spring International Conference on Material Sciences and Technology, MST-S 2013

作者： Li, Xing Xing Yi, Chun Hai Yang, Bo Lun Zhang, Yong Men, Chang Gui He, Gen Liang Xu, Hong Dong Department of Chemical Engineering State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China Northwest Research Institute of Chemical Industry Xi'an Shaanxi 710049 China

ISBN: (纸本)9783037857090

Considering the volumetric reactions and particle surface reactions in an entrained flow gasifier, the non-premixed combustion model based on the wet particles combustion method is adopted to simulate the multi-component slurry gasification process with FLUENT software. The velocity, temperature and concentration profiles of the gas products in the gasifier are obtained. Simulated results agree well with the commercial data, which verified the validity and applicability of the present model. Simultaneously, the reaction subarea in the gasifier has turned out to be obvious, the water evaporation, volatiles cracking and combustion reactions mainly appear in the jet region of the gasifier, the char gasification mainly appear in the freeboard region, but few reactions appear in the recirculation region. Moreover, with the increase of the mass fraction of the multi-component slurry, the content of the syngas at the gasifier outlet increases, while with the oxygen carbon atom ratio increasing, the syngas yield is rising early but declining later. © (2013) Trans Tech Publications, Switzerland.

关键词： Surface reactions

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Sensitive measurement of trace mercury using low pressure laser-induced plasma

Sensitive measurement of trace mercury using low pressure la...

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作者： Wang, Zhenzhen Deguchi, Yoshihiro Kuwahara, Masakazu Zhang, Xiaobo Yan, Junjie Liu, Jiping State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an 710049 China Graduate School of Advanced Technology and Science University of Tokushima Tokushima 770-8501 Japan

The emission of trace heavy metals, such as mercury (Hg), from power plants and other industries is a severe environmental problem concerning the public health. The laser-induced plasma technique was employed to measure Hg under various conditions, which reveals several merits of this method at low pressure. The main interferences of laser-induced breakdown spectroscopy (LIBS), which include the black-body-like emission from plasma itself and coexisting molecular and atomic emissions, decreased significantly using low pressure laser-induced plasma. Under low pressure conditions, Hg signal was rather clear without serious influence even if there is no delay time from the laser irradiation, which means the gated detection device is not necessary. This method featured the detection limit of 0.3 ppm at pressure 700 Pa. Additionally, the feasible of this method in real applications was demonstrated by measuring Hg in combustion gas which performed preferable results. © 2013 The Japan Society of Applied Physics.

关键词： Laser induced breakdown spectroscopy

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Enhancement of Photoelectrochemical Performance by Doping Tantalum Ions in Hematite （a-Fe2O3） Nanorod Photoanodes

Enhancement of Photoelectrochemical Performance by Doping Ta...

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International Conference on Nanoscience & Technology,China 2013(ChinaNANO 2013)

作者： Yanming Fu Liang Zhao Shaohua Shen State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

Ta-doped hematite (α-Fe 2 O 3 ) nanorod array electrodes were successfully prepared on FTO substrates using the conventional method by adding TaCl 5 in the aqueous solution directly. With the increasing of TaCl 5 dopant content, the photoelectrochemical (PEC) activity of the Ta-dopedα-Fe 2 O 3 nanorod films firstly increased and then decreased. Compared with the undoped α-Fe2O3 nanorod films, the optimal content of Ta-doped hematite sample showed about 3.5 times higher photoelectrochemical activity under the irradiation of solar light (AM 1.5, 100 mW·cm-2), as high as 0.53 mA·cm -2 at 0.5V vs. SCE(saturated calomel electrode) in 0.5 M Na 2 SO 4 . In order to analyze the mechanism of tantalum ions in changing the photoelectrode performance, all films were characterized by Raman spectra, UV-visible spectra, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrum(EDX) and X-ray photoelectron spectroscopy (XPS). The results reveal that at low Ta doping contents, small amount of Ta is dopedinto the nanorods of α-Fe 2 O 3 films and the photocurrent improvement is mainly attributed to the reduced electron-hole recombination in the α-Fe 2 O 3 nanorod *** at high Ta doping contents, superfluous Ta dopant forms a thick tantalum oxide layer and the layer completely covers the nanorods of α-Fe 2 O 3 films. This special surface structure reduces the number of photogenerated electrons (or holes) and weakens the charge transfer ability to raise the surface charge recombination of α-Fe 2 O 3 nanorods, leading to the decreased photoelectrochemical activity.

关键词： α-Fe 2 O 3 , nanorods, photoelectrochemical, doping

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EROSION PREDICTION OF LIQUID-PARTICLE TWO-PHASE flow IN PIPE ELBOWS VIA CFD-DEM COUPLING METHOD

EROSION PREDICTION OF LIQUID-PARTICLE TWO-PHASE FLOW IN PIPE...

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2013中国工程热物理学会多相流学术年会

作者： J.K.Chen Y.S.Wang S.Han Y.L.Chen State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

Erosion is a wear damage caused by the impact of small and loose moving particles to the surface and erosion damage is commonly encountered in petroleum exploitation and transportation engineering,especially such pipeline components as tees,elbows and reducers in long-distance crude-oil transmission *** 1990,Humphrey [1] presented an extensive review on erosion and pointed out that the particle incidence speeds,incidence angles and material-related aspects have great influence on surface erosion in ***,the theoretical research on erosion is still in development and no single erosion model or equation could be found for general and practical uses [2].Therefore,the study on the particle motion characteristics and erosion properties and the accurate prediction of erosion damage seem to have important academic significance and engineering application *** recent decade,Computational Fluid Dynamics(CFD) method has behaved as a serviceable approach to predict fluid flow and a supplementary means to study ***,most of the literature on CFD-based erosion research ignores the effect of particles to fluid flow and the impact among particles,which is a one-way or two-way coupling method that is only suitable for the cases with lower particle volume *** this study,the Discrete Element Method(DEM) has been applied in combination with CFD,in which the interaction of liquid-particle,particle-particle,and particle-wall are taken into *** volume averaging continuity and momentum equations as well as the standard k-ε model for turbulent have been adopted for modeling of the continuous carrier fluid *** motion of particles has been modeled as a discrete phase,described by the Newton's laws of motion on an individual *** interaction between fluid and particles has been expressed by the Di Felice Drag Model [3].When a particle contacts with other particles or wall,the soft-sphere model [4] is *** erosion pr

关键词： Liquid-particle two-phase flow Erosion Elbow CFD-DEM Numerical simulation

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Effect of flow acceleration on deformation and adhesion dynamics of captured cells

Effect of flow acceleration on deformation and adhesion dyna...

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作者： He, L. Luo, Z.Y. Xu, F. Bai, B.F. State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University China Bioinspired Engineering and Biomechanics Center Xi'An Jiaotong University China Key Laboratory of Biomedical Information Engineering School of Life Science and Technology Xi'An Jiaotong University Xi'an 710049 China

Cell deformation and adhesion under shear flows play an important role in both cell migration in vivo and capture based microfluidic devices in vitro. Adhesion dynamics of captured cell (e.g., firm adhesion, cell rolling and cell detachment) under steady shear flows have been studied extensively. However, cell adhesion under accelerating flows is common both in vivo and in vitro, and dynamics of cell adhesion under accelerating flows remains unknown. As such, we used a mathematical model based on the front tracking method and investigated the effect of flow acceleration on deformation and adhesion dynamics of captured cells, including cell deformation index, cell shape evolution, the velocities of cell center, contact time and wall shear stress for cell rolling and detachment by using a series of parameter values for leukocyte. The results showed that the cell presented three dynamics states (i.e., firm adhesion, rolling and detachment) with increasing wall shear stress under uniform flows. Wall shear stresses were 1.12 Pa for firm adhesion and detachment, respectively. The wall shear stresses were at the range 1.48-1.63 Pa (higher than 1.12 Pa) when cell left the bottom surface of the channel under flow accelerations (a = 0.975-1.625 m/s2). The minimum of deformation index under accelerating flow was smaller than that under uniform flow. In conclusion, the flow acceleration promotes the deformation and adhesion of captured cells. These findings could further the understanding of cell migration in vivo and promote the development of capture based microfluidic devices in vitro. © World Scientific Publishing Company.

关键词： Cells

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Graphitic carbon nitride modified by silicon for improved visible-light-driven photocatalytic hydrogen production

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Nanostructured Materials and Nanotechnology V - 36th International Conference on Advanced Ceramics and Composites, ICACC 2012

作者： Wu, Po Shi, Jinwen Chen, Jie Wang, Bin Guo, Liejin International Research Center for Solar-Hydrogen Renewable and Clean Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University 28 West Xianning Street Xi'an 710049 China

ISBN: (纸本)9781118205976

In this work, composites of silica and graphitic carbon nitride (g-C3N4) were conveniently synthesized through polymerization of melamine and ethyl silicate. Some basic physicochemical properties of these metal-free photocatalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS), Fourier transform infrared spectrometer (FTIR) spectra, transmission electron microscope (TEM), UV-visible diffuse reflectance spectrum and N2 adsorption-desorption measurement. The XRD patterns of all the prepared materials were dominated by the characteristic (002) peak at 27.5° of a graphitic structure, indicating that the induced Si did not destroy the crystal structure of g-C3N4). As the initial molar ratio of Si to C increased, enhanced photocatalytic activity was observed for H2 evolution from a triethanolamine aqueous solution under visible-light irradiation over the series of composites. It was proved that the introduction of Si resulted in large surface area, which is favorable for reactant-transfer and charge-migration, beneficial for photocatalysis.

关键词： X ray diffraction

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