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UK-China Symposium of New Energy Materials and Nanotechnology(2012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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Ab initio investigation of defect formation at ZrO2-CeO2 interfaces

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Physical Review B 2012年第8期86卷 085407-085407页

作者： Marco Fronzi Silvia Cereda Yoshitaka Tateyama Alessandro De Vita Enrico Traversa International Center for Materials Nanoarchitectonics (MANA) National Institute for Materials Science (NIMS) Tsukuba Japan Physics Department King's College London Strand London United Kingdom International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xian Jiaotong University Xian Shaanxi China

The structural and electronic properties of low index (100) and (111) ZrO2-CeO2 interfaces are analyzed on the basis of density functional theory calculations. The formation energy and relative stability of substitutional defects, oxygen vacancies, and vacancy-dopant complexes are investigated for the (100) orientation. By comparing these results with the ones obtained in bulk structures, we provide a possible explanation for the higher experimental ionic conductivity measured at the interface.

关键词： ZIRCONIUM oxide CERIUM oxides INTERFACES (Physical sciences) CRYSTAL defects ELECTRONIC structure

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Effect of nozzle size on the surface heat transfer dynamics during cryogen spray cooling in dermatologic laser surgery

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Zhongguo Jiguang/Chinese Journal of Lasers 2012年第3期39卷

作者： Zhou, Zhifu Wang, Rui Wang, Guoxiang Guo, Liejin Chen, Bin Wang, Yueshe State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China Department of Mechanical Engineering University of Akron Akron OH 44325 United States

Cryogen spray cooling (CSC) in conjunction with laser therapy has been the clinical standard for hypervascular lesions. In order to optimize nozzle and enhance the cooling efficiency to improve the treatment of laser surgery, an experimental system of transient cryogen spray cooling is built and eight straight-tube nozzles with different diameter and length are designed. A thin film thermocouple is directly deposited on the cooling surface to measure the surface temperature during the cryogen spray cooling. An analytical expression based on Fourier's law and Duhamel's theorem is used to calculate surface heat flux from the temperature measurements. Based on the measurements and calculations, the effect of the eight straight-tube nozzles on the heat transfer dynamics of the cooling surface and the atomization characterics are comparatively studied. Additionally, the criterion to evaluate the cooling efficiency of different nozzles is proposed, and the variation of heat extraction from the cooling surface with different spray distances by different nozzles is given.

关键词： Heat flux

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Experimental study of natural convection in horizontally-positioned open-celled metal foams

Experimental study of natural convection in horizontally-pos...

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International Conference on Materials for Renewable Energy and Environment

作者： Xu, Z.G. Qu, Z.G. Zhao, C.Y. State Key Laboratory of Multiphase Flow School of Energy and Power Engineering Xi'An Jiaotong University China

ISBN: (纸本)9781612847504

Experimental study of air natural convection in horizontally-positioned copper metallic foams with open cells was conducted. Temperature distributions on the heating surface were tested under different heating power for foam samples having different porosities and pore densities. The effects of porosity and pore density on the total thermal resistance of the foam sample were quantified. It is found that the porous surface can enhance the natural convection and reduce the thermal resistance by about 20% in comparison with a smooth surface. The surface area density and mass flow rate in natural convection are affected by porosity and pore density simultaneously. When the porosity is relative small (Ε = 90%), there exits a critical value of the Gr number (turning point) for two pore densities (10ppi and 40ppi). When the Gr number is less than this critical value, the foam with a higher pore density has the lower total thermal resistance, whereas when the Gr number exceeds the turning point value, the opposite holds. If the porosity is increased to Ε = 95%, the foam with a higher pore density has the lower thermal resistance in the whole experimental range. When the porosity and pore density is the same, the foam with smaller size has the higher thermal resistance in the whole experimental range. If the size is relatively small (10010050mm), for the two pore densities studied (20ppi and 80ppi), there exits a critical value of the Gr number (turning point). The foam with a lower porosity(Ε = 90%) has the lower thermal resistance and the decrease is more obvious for the case of *** the size is relatively big(10010080mm),there exists a critical value of the Gr number (turning point) only for the case of 10ppi. When the Gr number is less than this critical value, the foam with a higher porosity (Ε = 95%) has the higher total thermal resistance, the opposite holds. While for the other two pore densities (20ppi and 40ppi), there is no turning point. The foam with a highe

关键词： Natural convection

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Optimization on ignition timing and EGR ratio of a spark-ignition engine fuelled with natural gas-hydrogen blends

Optimization on ignition timing and EGR ratio of a spark-ign...

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SAE 2011 World Congress and Exhibition

作者： Hu, Erjiang Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an 710049 China

In this paper, 20%H2 (20% hydrogen in natural gas-hydrogen blends, by volume) is selected as the test fuel, and the ignition timing and EGR ratio are adjusted to optimize the performance, combustion, and emissions of a natural gas-hydrogen engine. An experimental investigation on the effect of ignition timings, EGR ratios on combustion behaviors and emissions of a spark-ignition engine fuelled with natural-gas and hydrogen blends was conducted. When increasing the ignition timing at specified EGR ratio, engine power output will give its peak value at MBT timing. Large EGR introduction decreases engine power output and increases combustion duration. Effective thermal efficiency shows an increasing trend at the small EGR ratio and a decreasing trend with further increasing EGR ratio. With advancing the ignition timing, the flame development duration is increased, and the rapid combustion duration and total combustion duration are decreased. All of these three kinds of combustion duration are increased with the increase of EGR ratio. HC concentration is decreased and NOx concentration is increased with advancing the ignition timing while CO emission varies little with the ignition timing. NOx concentration is decreased with the increase of EGR ratio. HC emission is increased with the increase of EGR ratio. CO and CO2 emissions show little variations with the EGR ratio and ignition timing. Based on the above analysis, a MAP containing ignition timings and EGR ratios for 20%H2 fuel blend is presented, and this will provide the reference and guidance to engine designers and engineers. In addition, through optimizing ignition timing and EGR ratio, high efficiency and low emission spark-ignition engine can be realized fueled with natural gas-hydrogen blends. Copyright © 2011 SAE International.

关键词： Natural gas

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Exhaust recovery of vehicle gasoline engine based on organic rankine cycle

Exhaust recovery of vehicle gasoline engine based on organic...

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SAE 2011 World Congress and Exhibition

作者： Zhang, Xinxin Zeng, Ke Bai, Sujuan Zhang, Ying He, Maogang State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an Shaanxi 710049 China

When the global energy consumption continues to increase, the research hotspot in the field of internal combustion engine (ICE) is how to improve the fuel utilization efficiency to achieve the energy saving. But as far as the engine efficiency is concerned, it has been very difficult to improve the fuel utilization efficiency after the Gasoline Direct-Injection (GDI) and Homogeneous Charge Compression Ignition (HCCI) technology were adopted. In this study, the exothermic distribution of fuel was studied detailedly when a TOYOTA 8A-FE gasoline engine operated at different working conditions through conducting steady-state experiment. Only one third of fuel's chemical energy is converted into effective work by engine, the rest is released to the environment in the form of waste heat generated from cooling and exhaust gas. But except the waste heat that has to be released to the environment according to the second law of thermodynamics, the rest can be theoretically utilized. If the waste heat of the vehicle engine can be recovered, the engine efficiency will be evidently improved. Results on the exergy analysis show that the exergy in the exhaust gas is about 45-70% and it will evidently increase with the increase of engine load and revolution. So it will have a good effect on exhaust recovery when the engine has a heavy load. Considering the character of exhaust gas, the Organic Rankine Cycle(ORC) is adopted to recover the waste heat of engine's exhaust gas. The thermodynamic performances of the cycle were analyzed and R113 was determined to be the working fluid. The experimental exhaust gas recovery system used to testify the aforementioned theoretical calculation was designed and established. The system consists of exhaust gas simulation device, expander, condenser, dynamometer, pump and data acquisition and processing system. In experiment, the performance parameter and power output of the Organic Rankine Cycle were measured. The expander show a high isentropic ef

关键词： Recovery

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Eosin Y-sensitized ZnO/TiO2 for efficient visible light photocatalytic hydrogen evolution

Eosin Y-sensitized ZnO/TiO2 for efficient visible light phot...

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2011 MRS Spring Meeting

作者： Liu, Haipei Jing, Dengwei Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 China

ISBN: (纸本)9781618395238

In this work a series of Eosin Y-ZnO(x%)/TiO2 were prepared. ZnO well dispersed on the surface of TiO2, which improves the adsorption of Eosin Y and the excited electron to transfer to the conduction band of TiO2. Therefore the visible light activity of 0.2%Pt-Eosin Y-ZnO(x%)/TiO2 is much higher than that of the 0.2%Pt-Eosin Y-TiO2 and 0.2%Pt-Eosin Y-ZnO. The 0.2%Pt-Eosin Y-ZnO(1.5%)/TiO 2 has the highest visible light activity among the catalysts coupled with various ZnO amount, whose activity is increased by a factor of 3.5 compared to that of 0.2%Pt-Eosin Y-TiO2. It is proposed that, 0.2%Pt-Eosin Y-ZnO(1.5%)/TiO2 has the optimal trapping sites of carriers and thickness of the space-charge layer on the TiO2 particle surface, so these factors result a more efficient charge separation, an increased lifetime of the charge carriers, and the enhanced of hydrogen production. © 2011 Materials Research Society.

关键词： Titanium dioxide

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Photocatalytic reforming of formic acid with simultaneous hydrogen production under visible light over CdS sensitized Na2Ti 2O4(OH)2

Photocatalytic reforming of formic acid with simultaneous hy...

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2011 MRS Spring Meeting

作者： Tang, Wendong Jing, Dengwei Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China

ISBN: (纸本)9781618395238

The present work reports the renewable hydrogen production by an anaerobic photocatalytic reforming of formic acid over CdS sensitized Na 2Ti2O4(OH)2 nanotubes, the Na 2Ti2O4(OH)2 nanotube was prepared and charactered by X-ray diffraction, UV-visible absorption, transmission electron microscopy, etc. The activity of the catalyst in formic acid was investigated. The greatest photocatalytic reforming activity of formic acid occurs as the formic acid initial concentration is 20 v.%. A probable mechanism for the photocatalytic reforming process was proposed and discussed. © 2011 Materials Research Society.

关键词： Cadmium sulfide

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Performance of a domestic refrigerator using TiO2-R600a nano-refrigerant as working fluid

Performance of a domestic refrigerator using TiO2-R600a nano...

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作者： Bi, Shengshan Guo, Kai Liu, Zhigang Wu, Jiangtao State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China

In this work, an experimental work was investigated on the nano-refrigerant. TiO2-R600a nano-refrigerants were used in a domestic refrigerator without any system reconstruction. The refrigerator performance was then investigated using energy consumption test and freeze capacity test. The results indicate that TiO2-R600a nano-refrigerants work normally and safely in the refrigerator. The refrigerator performance was better than the pure R600a system, with 9.6% less energy used with 0.5 g/L TiO2-R600a nano-refrigerant. Thus, using TiO2-R600a nano-refrigerant in domestic refrigerators is feasible. © 2010 Elsevier Ltd. All rights reserved.

关键词： Refrigerators

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Shock tube study on auto-ignition characteristics of kerosene/air mixtures

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Chinese Science Bulletin 2011年第13期56卷 1399-1406页

作者： ZHANG YingJia HUANG ZuoHua WANG JinHua XU ShengLi State Key Laboratory of Multiphase Flow in Power Engineering Xi' an Jiaotong University Xi' an 710049 China Department of Modern Mechanics University of Science and Technology of China Hefei 230026 China

Ignition delay times are obtained for kerosene/air mixtures behind the reflected shock waves at temperatures between 1445 and 1650 K,at a pressure of 0.11 MPa and an equivalence ratio of 1.0.A nebulization device with Laval nozzle is used to nebulize kerosene and form an aerosol phase,which evaporates and diffuses rapidly behind the incident shock *** auto-ignite behind the reflected shock *** ICCD is used to visualize the kerosene/air mixture's ignition *** mixture's ignition intensity increases with increase in initial *** and irregular flames exist below 1515 K while plane and discontinuous flames exist over 1560 *** delay times decrease with increase in initial *** data shows good agreement with results reported previously in the literature.A new surrogate (consisting of 10% toluene,10% ethylbenzene and 80% n-decane) is proposed for *** et al.'s mechanism is used to simulate the ignition of kerosene with calculations agreeing well with the experimental *** sensitivity of reaction H+O2 <=>OH+O,which shows the highest sensitivity to the ignition delay time,increases with an increase in *** chain breaching reaction of CH3 with O2 accelerates the total reaction rate and the H-atom abstraction of n-decane controls the total reaction *** rate of production and instantaneous heat production indicate that two reactions,H+O2 <=>OH+O and O+H2 <=>OH+H,are the key reactions to the formation of OH radicals,as well as the main endothermic ***,the reaction of R3 is the main heat release reaction during *** structure analysis shows that initial pressure is increased slightly as CO and H2O will appear before main ignition.

关键词：空气混合物煤油自燃特性点火延迟时间冲击管反应速率初始温度数据显示

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