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9th International Conference on Modeling and Diagnostics for Advanved Engine Systems, COMODIA 2017

作者： Hu, Erjiang Gao, Zhenhua Ku, Jinfeng Meng, Xin Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Ignition delay times of 2, 5-dimethylfuran(2, 5-DMF)/n-heptane/oxygen/argon mixtures were measured in this study. Experiments were performed at the stoichiometric mixtures in the temperature range of 1200-1800K. A blend model for 2, 5-DMF/n-heptane blends was developed by combining two selected models for each individual fuel component. According to the combined model, the ignition delay time increases with an increase in the 2, 5-DMF addition level, non-linearly. Kinetic analysis was conducted to investigate interaction effects between two fuels. At relatively low blending ratios of 2, 5-DMF, the two fuels have negligible impacts on the reaction path of each other. As the 2, 5-DMF addition increases to relatively higher levels, decomposition path of n-heptane is significantly changed due to the competition for small radical. Copyright © 2017 by the Japan Society of Mechanical Engineers.

关键词： Heptane

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MPS analysis of molten corium jet and structure interaction during nuclear severe accident 17

MPS analysis of molten corium jet and structure interaction ...

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17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2017

作者： Li, Gen Zhang, Jun Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

The melt jet and structure interaction is an important phenomenon in the progression of nuclear severe accident. It could happen when molten corium relocates onto core plate and Reactor Pressure Vessel (RPV) lower head, and in the ex-vessel accident, the molten corium may directly impinge onto and Erode concrete. In the present study, a numerical code was developed based on Moving Particle Semi-implicit (MPS) method, to analyze the erosion scenario of RPV wall and dry concrete by melt jet. The numerical modeling was validated by comparing structure erosion configuration and time-dependent erosion depth with the experimental data. In the analysis of RPV wall erosion, it indicates that no crust layer presented at the interaction of stainless steel (SS) melt jet and RPV wall, while for Zr, ZrO2 and UO2 melt jets the crust layer presented. At a superheat temperature equal to 300 K, the erosion rate by SS melt was the fastest, even though the absolute temperature was the lowest compared with other cases. In the analysis of melt jet and concrete interaction, the core melt was divided as metallic material (SS-Zr) and oxide material (ZrO2-UO2). The results indicate that the crust and ablated concrete layer presented at the interface of UO2-ZrO2 melt and concrete, whereas no crust could be found in the interaction of SS-Zr melt with concrete. The erosion progression was faster in the erosion by metallic melt jet than by oxidic melt jet. The present analysis demonstrates that the erosion rate was affected not only by temperature, but also by crust layer, and the major threat to structure was metallic melt, especially at high temperature. © 2016 Association for Computing Machinery Inc. All Rights Reserved.

关键词： Erosion

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Numerical analysis of the static performance of an annular aerostatic gas thrust bearing applied in the cryogenic turbo-expander of the EAST subsystem

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Plasma Science and Technology 2017年第2期19卷 115-122页

作者： Tianwei LAI Bao FU Shuangtao CHEN Qiyong ZHANG Yu HOU State Key Laboratory of Multiphase Flow in Power Engineering Xi＇an Jiaotong University Xi＇an 710049 People＇s Republic of China Institute of Plasma Physics Chinese Academy of Sciences Hefei 230031 People＇s Republic of China

The EAST superconducting tokamak, an advanced steady-state plasma physics experimental device, has been built at the Institute of Plasma Physics, Chinese Academy of Sciences. All the toroidal field magnets and poloidal field magnets, made of NbTi/Cu cable-in-conduit conductor, are cooled with forced flow supercritical helium at 3.8 K. The cryogenic system of EAST consists of a 2 kW/4 K helium refrigerator and a helium distribution system for the cooling of coils, structures, thermal shields, bus-lines, etc. The high-speed turbo-expander is an important refrigerating component of the EAST cryogenic system. In the turbo-expander, the axial supporting technology is critical for the smooth operation of the rotor bearing system. In this paper, hydrostatic thrust bearings are designed based on the axial load of the turbo-expander. Thereafter, a computational fluid dynamics-based numerical model of the aerostatic thrust bearing is set up to evaluate the bearing performance. Tilting effect on the pressure distribution and bearing load is analyzed for the thrust beating. Bearing load and stiffness are compared with different static supply pressures. The net force from the thrust bearings can be calculated for different combinations of bearing clearance and supply pressure.

关键词： EAST helium cryogenic system aerostatic thrust beating inclination bearing load

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Transient Evaporation Simulation of the Forced Circulation Hot Water Boiler

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IOP Conference Series: Materials Science and engineering 2020年第1期721卷

作者： Junjie Bao Di Wang Feng Liu Zhiguo Qu Hongtao Xu Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai 200093 China Shanghai Institute of Special Equipment Inspection and Technical Research Shanghai 200062 China China Special Equipment Inspection and Research Institute Beijing 10013 China Moe Key Laboratory of Thermo-Fluid Science and Engineering Xi'an Jiaotong University Xi'an 710049 China

This paper presents a comprehensive analysis of the water vaporization in a hot water boiler system. The Computational Fluid Dynamics (CFD) technology was adopted to simulate the transient water evaporation in the boiler termed as DZL14-1.25/115/70-AⅡ under the assumption of extreme conditions such as the water pump failure. The results indicated that the average pressure in the pipeline increased from 0.57Mpa to 0.66Mpa (the setting pressure of the safety valve) within 1050s. The pressure increased rapidly with the time increase. The average temperature of hot water changed linearly with time, and the internal thermal deviation of the hot water pipeline in the boiler decreased with time. The internal vaporization phenomenon of the hot water boiler became significant under the extreme condition. The steam flowed upward and accumulated in the upper part of the boiler shell. At 1050s, the vapor volume fraction in the hot boiler was 1.05%, which indicated that the safety valve above the stream shell need to be opened in time after 1050s to ensure the safety of the boiler.

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Theoretical insights into the hydrophobicity of low index CeO2 surfaces

arXiv

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arXiv 2019年

作者： Fronzi, Marco N. Assadi, M. Hussein Hanaor, Dorian A.H. International Research Centre for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’anShaanxi710049 China 1-1 Namiki TsukubaIbaraki305-0044 Japan Chair of Advanced Ceramic Materials Institute for Materials Science and Technology Technische Universität Berlin Berlin10653 Germany

The hydrophobicity of CeO2 surfaces is examined here. Since wettability measurements are extremely sensitive to experimental conditions, we propose a general approach to obtain contact angles between water and ceria surfaces of specified orientations based on density functional calculations. In particular, we analysed the low index surfaces of this oxide to establish their interactions with water. According to our calculations, the CeO2 (111) surface was the most hydrophobic with a contact angle of Θ = 112.53° followed by (100) with Θ = 93.91°. The CeO2 (110) surface was, on the other hand, mildly hydrophilic with Θ = 64.09°. By combining our calculations with an atomistic thermodynamic approach, we found that the O terminated (100) surface was unstable unless fully covered by molecularly adsorbed water. We also identified a strong attractive interaction between the hydrogen atoms in water molecules and surface oxygen, which gives rise to the hydrophilic behaviour of (110) surfaces. Interestingly, the adsorption of water molecules on the lower-energy (111) surface stabilises oxygen vacancies, which are expected to enhance the catalytic activity of this plane. The findings here shed light on the origin of the intrinsic wettability of rare earth oxides in general and CeO2 surfaces in particular and also explain why CeO2 (100) surface properties are so critically dependant on applied synthesis methods. Copyright © 2019, The Authors. All rights reserved.

关键词： Density functional theory

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Theoretical analyses of the sub-grid quantities' effect on filtered eulerian drag force

arXiv

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arXiv 2018年

作者： Chen, Xiao Jiang, Ming Zhou, Qiang State Key Laboratory of Multiphase Flow in Power Engineering Xian Jiaotong University Xian710049 China School of Chemical Engineering and Technology Xian Jiaotong University Xian710049 China

An expression of the filtered Eulerian drag force is proposed based on the second order Taylor polynomial approximation of the microscopic Eulerian drag coefficient. Theoretical computations of the expression are performed at low Reynolds numbers based on an available microscopic drag model. It shows that four sub-grid quantities, i.e., the gas drift velocity, the solid drift velocity, the scalar variance of solid volume fraction and a third-order moment, defined as the covariance of squared solid volume fraction and the slip velocity, are significant for an accurate estimation of the filtered drag force at low Reynolds numbers. The gas drift velocity is nothing but the drift velocity defined by Parmentier et al. (AIChE Journal, 2012, 58 (4): 1084-1098), and in analogy to the gas drift velocity, we defines the solid drift velocity in the present work. The great relevance of the gas drift velocity and the scalar variance of solid volume fraction to the filtered drag force have been demonstrated through numerous correlative analyses of fully resolved simulations. Present theoretical analysis shows that the gas drift velocity term is primarily responsible for the drag reduction, whereas the solid drift velocity term is prone to attenuate this reduction, especially at moderate and high solid volume fractions. The scalar variance of solid volume fraction term is found to increase the filtered drag force in the full range of solid volume fractions. The third-order term has exactly the same coefficient with that of the variance term, and it mostly attains negative values with the trend to decrease the filtered drag force. Copyright © 2018, The Authors. All rights reserved.

关键词： Drag

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Transport equation for the drift velocity in predicting the filtered Eulerian drag force: A theoretical development

arXiv

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arXiv 2018年

作者： Chen, Xiao Jiang, Ming Zhou, Qiang School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

The drift velocity has been proven to have significant relevance to the filtered Eulerian drag force by numerous correlative analyses of fully resolved simulations. It is a sub-grid quantity defined as the difference between the filtered gas velocity seen by the particle phase and the resolved filtered gas velocity. In literature, it is shown that various algebraic models for the drift velocity fail to give entirely satisfactory prediction of the filtered drag force. Unlike previous works, we theoretically derived the transport equation for the drift velocity from the standard two-fluid model (TFM) equations without any additional assumptions. The new approach, though requires additional closures for the new unresolved terms, is believed to have the potential to improve the precision of the estimation of this sub-grid quantity and hence give better prediction of the filtered drag force for gas-solid fluidization problems. Copyright © 2018, The Authors. All rights reserved.

关键词： Drag

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A High-Performance VS2-Modifed Separator for Lithium–Sulfur Batteries

A High-Performance VS2-Modifed Separator for Lithium–Sulfur...

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中国化学会第三届中国能源材料化学研讨会

作者： Jianan Wang Guorui Yang Shanshan Yi Ling Wang Silan Wang Wei Yan Shujiang Ding Department of Environmental Science and Engineering State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong University Department of Applied Chemistry School of ScienceState Key Laboratory for Electrical Insulation and Power EquipmentXi'an Jiaotong Univrsity School of Electronic and Information Engineering Xi'an Jiaotong University

Lithium–sulfur（Li-S） batteries are a promising candidate to couple renewable energy sources for green transportation and large-scale energy storage because of their relatively low cost and high theoretical specific capacity(1,675 mA h g).However,a major problem preventing the practical applications of Li-S batteries is the rapid capacity fading,predominantly due to the "shuttle effect" of polysulphides（LiPSs）.

关键词： A High-Performance VS2-Modifed Separator for Lithium Sulfur Batteries

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A mesh mapping method for MCNP and fluent coupling simulation

A mesh mapping method for MCNP and fluent coupling simulatio...

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2017 Transactions of the American Nuclear Society, ANS 2017

作者： Wang, Xinan Zhang, Dalin Wang, Mingjun Tian, Wenxi Qiu, Suizheng Su, Guanghui State Key Laboratory of Multiphase Flow in Power Engineering School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an710049 China

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Theoretical investigation on heat-electricity decoupling technology of low-pressure steam turbine renovation for CHPs

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IOP Conference Series: Earth and Environmental Science 2019年第4期227卷

作者： Qingbo Hu Kun Wang Li Zhang Liansheng Zhou Rong Chen Shan Wang Yu Zhang Guohao Li Tianjin Electric Power Science & Research Institute Tianjin 300384 State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiao Tong University Xi'an 710049.

The power grid peaking capacity is insufficient due to the increasing installed capacity of renewable power. Moreover, it is also restricted by the operation mode of combined heat and power units (CHPs), the minimum electricity loads of which are determined by the heat load. It is significant to study the heat-electricity decoupling technologies for CHPs. Therefore, the low-pressure steam turbine renovation technology is studied in this paper with a 300MW unit as reference case. Results show that the minimum electric load rate and the coal consumption are decreased, and the heat-electricity ratio is increased significantly for CHP with low-pressure steam turbine renovation. When the heat load is 1200 GJ/h, the minimum electric load rate and coal consumption with low-pressure steam turbine renovation can be reduced by 32.4 and 30.9 % respectively. The heat-electricity ratio can be increased by 68.8 % after renovation of low-pressure steam turbine.

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