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Exergy analysis of solar dynamic closed Brayton cycle for space applications

Taiyangneng Xuebao/Acta Energiae Solaris Sinica 2010年第3期31卷 351-356页

作者： Chen, Shuangtao Hou, Yu Chen, Liang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Exergy analysis of solar dynamic closed Brayton cycle (SDCBC) for space applications was presented in this paper. An integrated model for the system and specific models for its components were proposed. Influence of main parameters on system exergy efficiency was discussed. The results shown the efficiencies of expander, compressor, and regenerating temperature of the regenerator have significant influence on the exergy efficiency of SDCBC system. Therefore, besides the enhancement of component efficiencies, the matching among components of SDCBC system should be also taken into account. Moreover, it would be always desirable to enhance the effectiveness of recuperator within the requirements of flow resistance and system weight.

关键词： Space applications

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Numerical simulation of a buried hot crude oil pipeline during shutdown

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Petroleum Science 2010年第1期7卷 73-82页

作者： Xu Cheng Yu Bo Zhang Zhengwei Zhang Jinjun Wei Jinjia Sun Shuyu Beijing Key Laboratory of Urban Oil and Gas Distribution Technology China University of Petroleum Beijing 102249China Zhejiang Department Preparatory Team PetroChina West East Gas Pipeline Company Hangzhou Zhejiang 310000 China State Key Laboratory of Multiphase Flow in Power Engineering Xi＇an Jiaotong University Xi＇an Shaanxi 710049 China Department of Mathematical Sciences Clemson University Clemson SC 29634-0975 USA

In this paper a mathematical model is built for a buried hot crude oil pipeline during shutdown, and an unstructured grid and polar coordinate grid are respectively applied to generating grids for the soil region and the three layers in the pipe （wax layer, pipe wall, and corrosion-inhibiting coating）. The governing equations are discretized using the finite volume method. The variations in temperatures of static oil and soil were investigated during pipeline shutdown in both summer and winter, in which some important parameters of the soil and crude oils of a Northeast pipeline are employed.

关键词： Moving boundary stagnation point equivalent thermal conductivity thermal influence region unstructured grid

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Experimental study on the characteristics of weak corrosive surfactant drag reducer

Experimental study on the characteristics of weak corrosive ...

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12th International Conference on engineering, Science, Construction, and Operations in Challenging Environments - Earth and Space 2010

作者： Su, Wen-Tao Li, Feng-Chen Dong, Yong Cai, Wei-Hua Jiao, Li-Fang Wei, Jin-Jia Yu, Bo School of Energy Science and Engineering Harbin Institute of Technology Harbin 150001 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiao Tong University Xi'an 710049 China Beijing Key Laboratory of Urban Oil and Gas Distribution Technology China University of Petroleum Beijing 102249 China

ISBN: (纸本)9780784410967

Experimental study on drag-reducing characteristics of a zwitterionic surfactant additive (C20H43NO) in a circulation system has been carried out. It was based on the optimum concentration, temperature effect and the characteristics of resisting shear in DN27.5 pipeline. The results showed that C20H43NO additive has a significant drag-reducing effect depending on concentration and temperature. The most effective concentration in the tested flow loop was 900ppm at 60°C. The temperature range of the drag-reducing effect was in the range of 40 ∼ 70°C. The maximum drag reduction (DR) of 900ppm C20H 43NO aqueous solution was 77% at the beginning of circulation with system running between 41°C and 43°C. The drag-reducing effect does not decrease remarkably after the circulation system ran for a period of seven hours, but reduces to only 5% of DR after a period of twenty-three hours. In order to study the drag-reducing characteristics of C20H 43NO aqueous solution in the practical district heating system, the experiments with C20H43NO aqueous solution flow in different inner-diameter pipelines including DN50 and DN100 with rough wall were performed. The results indicated that the optimum drag-reducing concentrations are 1500ppm and 2500ppm at 45∼50°C in the DN50 and DN100 circular pipes, respectively. Finally, the technique of drag-reducing additive applying into the district heating system is discussed. And some problems in the practical application were brought forward, such as, the poor life-span of surfactant, the instabilities of drag-reducing effect and the inherent corrosion of additive itself. According to these problems, the corrosion research of C 20H43NO aqueous solution was also conducted based on immersion method. The results show that: C20H43NO aqueous solution is weakly corrosive for iron-based metallic pipe comparing with CTAC aqueous solution and water. © 2010 ASCE.

关键词： Pipelines

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Nitrogen, sulfur, and chlorine transformations during the pyrolysis of straw

Nitrogen, sulfur, and chlorine transformations during the py...

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作者： Wang, Xuebin Si, Jipeng Tan, Houzhang Ma, Lin Pourkashanian, Mohamed Xu, Tongmo State Key Laboratory of Multiphase Flow in Power Engineering Xian Jiaotong University Xian 710049 China Centre for Computational Fluid Dynamics School of Process Environmental and Materials Engineering University of Leeds LS2 9JT United Kingdom

Transformation of nitrogen, sulfur, and chlorine during straw pyrolysis at temperatures from 35 to 1450 °C was investigated by using the coupled thermogravimetry-differential scanning calorimetry-mass spectrometry (TG-DSC-MS) techniques and compared with that of coal. The characteristics of the residual solid char from the straw were analyzed using x-ray diffraction (XRD). Results show that all the nitrogen species (HCN, NH3, HNCO, and CH 3CN), chloric species (HCl and Cl2), and sulfur species (SO2, H2S and COS) began to release from straw from 200 °C, compared with 350 °C for the case of coal. Most of the gaseous species from the straw were released in the form of a sharp peak, compared with the coal which has a much wider peak. NH3 and HNCO were the primary nitrogen species for both straw and coal;however for the straw the amount of NH3 released was much higher than that of HNCO. Sulfur species from the straw pyrolysis are sparse, and there was only a little COS released. During coal pyrolysis no COS was detected at all and H2S was mainly formed at 500 °C∼600 °C. SO2 was released in three stages (300-500 °C, 500-600 °C and 1200-1450 °C), and the largest SO 2 emission was found at high temperatures due to the decomposition of sulfate. The major chloric species from the pyrolysis of both straw and coal was HCl, and the ion current intensity of Cl2 was very low. There was a critical temperature of around 800 °C, beyond which most of the chlorine would be released. © 2010 American Chemical Society.

关键词： Pyrolysis

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On Dynamic Behavior of Triangular Shaped Cantilevers in MEMS Sensors: Effect of Curvature

On Dynamic Behavior of Triangular Shaped Cantilevers in MEMS...

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2010 10th IEEE International Conference on Solid-state and Integrated Circuit Technology(第十届固态和集成电路技术国际会议 ICSICT-2010)

作者： Guo-Ying Yuan En-Ze Huang Gui-Ming Zhang Zhuang-De Jiang Li-Bo Zhao Yong Li Zhi-Gang Liu State Key Laboratory for Manufacturing Systems Engineering Xi'an Jiaotong University Xi'an 710049 State Key Laboratory for Manufacturing Systems Engineering Xi'an Jiaotong University Xi'an 710049 State Key Laboratory of Tribology Tsinghua University Beijing 100084 China State Key Lab of Multiple Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

ISBN: (纸本)9781424457977

A study on the effect of curvature of triangular shaped cantilevers in MEMS sensors was presented. 3-D models were performed by using the SolidWorks software. And modal analysis and harmonic response analysis were carried out on different types of geometrically configured triangular shaped cantilevers using ANSYS software. The results included the variation of natural frequencies of cantilevers and maximum equivalent von mises strain on the cantilevers with respect to radius of curvature of triangular shaped cantilevers. According to the finite element analysis results, the curvature did affect dynamic behavior of triangular shaped cantilevers in MEMS sensors. Usually, the curvature is induced by the surface stress due to microprocessing or any change of temperature, etc. Therefore, in order to achieve a steady state of strain for the MEMS sensors, it's better to eliminate the surface stress and make the cantilever transform from a curved cantilever to a straight cantilever.

关键词： CANTILEVER Curvature Surface stress Triangular Microelectromechanical systems Sensors Microtechnology Response analysis

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Water cut measurement of crude oil slug flow with double-tube capacitance sensor 6

Water cut measurement of crude oil slug flow with double-tub...

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6th World Congress in Industrial Process Tomography

作者： Bai, Bofeng He, Denghui Xu, Yong Yang, Canghai Li, Li State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Oil and Gas Technology Research Institute Changqing Oilfield Company of CNP Xi’an710021 China National Engineering Laboratory for Exploration and Development of Low-permeability oil and gas Field CNPC Beijing100007 China

ISBN: (纸本)9780853163220

An online method for measurement of water cut in the crude oil slug flow in vertical pipes is presented. The water cut is obtained from the water film length, which is measured by a double-tube capacitance probe sensor, on the surface-insulated tube. The double-tube capacitance probe sensor consists of two stainless steel tubes, one tube is covered with an insulating film and the other is not. There is a heating wire in each tube, which provides a certain amount of heat to prevent the formation of waxes on the surface of the tube. The output of water cut variations is in the form of capacitance signal, which is independent of water salinity and electrical properties of the liquid. The water film length, capacitance and water cut are linearly proportional to each other. The field experiments indicate that the measurements are affected by both the natural gas entrained in the liquid and the flow patterns. A comparison with manual sampling measurement suggests that the mean water cut obtained by the sensor is lower than that of manual sampling value in the slug flow and the relative deviation is 11.58%. The measured values are revised according to the water holdup of the slug flow, and the relative deviation is reduced to 8.04% after revising. © 2010, International Society for Industrial Process Tomography. All rights reserved.

关键词： Crude oil

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Modelling of water transport in PEM fuel cell

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2010年第9期31卷 1504-1507页

作者： Xu, Cheng-Jie Zhang, Guang-Sheng Liu, Hong-Tan Guo, Lie-Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Dept. of Mechanical and Aerospace Engineering University of Miami Coral Gables FL 33124 United States

A mixed-domain, two-phase flow, non-isothermal model is developed to study the water transport phenomena, which has significant effects on the performance of PEM fuel cells. Modelling results show that: the total water concentration is decreasing along the channel in anode, while it is increasing in cathode, flooding is most likely to occur at the end of cathode flow channel;liquid water in cathode GDL presents opposite distribution at high current density and low current density, the saturation of liquid water is decreasing from inner side to outer side across the GDL at low current density while it is increasing at high current density.

关键词： Two phase flow

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Hydrogen Production by CMC Gasification in Supercritical Water

Hydrogen Production by CMC Gasification in Supercritical Wat...

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IEEE PES Asia-Pacific power and Energy engineering Conference (APPEEC)

作者： Xiaohong Hao Liejin Guo Ximin Zhang School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

ISBN: (纸本)9781424448128;9781424448135

Hydrogen production by biomass supercritical water gasification is about to develop in the future because the process is closed and clean with high gasification efficiency in addition. Low concentration sodium carboxymethylcellulose (CMC) (2-3% mass fraction) can be mixed with particulate biomass and water to form a uniform and stable viscous paste which can be pumped to the continuous high-pressure reactor. In this paper, the supercritical water gasification of CMC was investigated in the tube flow apparatus to produce gas products consisting essentially of H 2 , CO, CH 4 and CO 2 .

关键词： Hydrogen Production Inductors Biomass Temperature Feeds Resistance heating Regulators Cooling Atmospheric measurements

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Photocatalytic desulfurization of gasoline by TiO2 coupling with ultrasonic

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Ranliao Huaxue Xuebao/Journal of Fuel Chemistry and Technology 2010年第4期38卷 428-433页

作者： Chen, Song-Xuan Zhao, Jing-Lian Su, Ci State Key Laboratory of Multiphase Flow in Power Engineering Department of Environmental Engineering Xi'an Jiaotong University Xi'an 710049 China

The photocatalytic oxidation of dibenzothiophen (DBT) in octance (as solvent) was conducted using O2 in air as the oxidant, TiO2 prepared by sol-gelatin method as the photocatalyst and coupling with ultrasonic. The effect of light distance, photocatalyst amount, reaction time, DBT initial concentration and ultasonic power on the removal of DBT were investigated deeply. The results show that the degradation rate of DBT increases by 10% by using ultrasonic. Under the conditions of TiO2 dosage of 2 g/L, air flow rate of 800 mL/min, distance of UV light of 20 cm, initial concentration of DBT of 600 mg/L, reaction time of 150 min, ultrasound power of 500 W, the degradation rate of DBT can reach up to 72.6%.

关键词： Ultrasonics

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Effect of Noble Metal in CdS/M/TiO ₂ for Photocatalytic Degradation of Methylene Blue under Visible Light

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International Journal of Green Nanotechnology: Materials Science and engineering 2010年第2期1卷 M94-M104页

作者： Shen, Shaohua Guo, Liejin Chen, Xiaobo Ren, Feng Kronawitter, Coleman X. Mao, Samuel S. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China Lawrence Berkeley National Laboratory University of California at Berkeley Berkeley CA 94720 United States

The CdS/M/TiO 2 (M = Ag, Ru, Au, Pd, and Pt) three-component nanojunction systems were constructed using a two-step photodeposition method, and evaluated for their photocatalytic activities through the degradation of ... 详细信息

The CdS/M/TiO ₂ (M = Ag, Ru, Au, Pd, and Pt) three-component nanojunction systems were constructed using a two-step photodeposition method, and evaluated for their photocatalytic activities through the degradation of methylene blue in aqueous solution under visible light irradiation. The authors found that the photocatalytic activity of CdS/M/TiO ₂ (M=Ag, Ru, Au, Pd, Pt) three-component nanojunctions was superior to that of CdS/TiO ₂ two-component system. Moreover, the photocatalytic activity of the three-component nanojunction system was found to be dependent significantly on the type of the noble metals. The results can be explained by the influence of charge transfer on the basis of the work functions of different noble metals. © 2010 Copyright Taylor and Francis Group, LLC.

关键词： CdS/M/TiO 2 heterojunction noble metal photocatalysis Z-scheme

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