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An investigation of flow characteristics and critical heat flux in vertical upward round tube

Nuclear Science and Techniques 2006年第3期000卷 170-176页

作者： FAN Pu QIU Sui-Zheng JIA Dou-Nan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Prediction of critical heat flux (CHF) in annular flow is important for the safety of once- through steam generator and the reactor core under accident conditions. The dryout in annular flow occurs at the point where the film is depleted due to entrainment, deposition, and evaporation. The film thickness, film mass flow rate along axial distribution, and CHF are calculated in vertical upward round tube on the basis of a separated flow model of annular flow. The theoretical CHF values are higher than those derived from experimental data, with error being within 30%.

关键词： Annular flow Critical heat flux Dryout Entrainment Deposition

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The optimized design and experimental analysis of CPC-PV / T system

The optimized design and experimental analysis of CPC-PV / T...

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International Conference on Renewable power Generation, RPG 2015

作者： Chen, Haiping Wang, Chenhui Sun, Jieling Ai, Dengxin Ye, Chentao Li, Zhaohao Wei, Jinjia School of Energy Power and Mechanical Engineering National Thermal Power Engineering and Technology Research Center North China Electric Power University Beijing102206 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shanxi Province710049 China

ISBN: (纸本)9781785610400

With the CPC integrated photovoltaic / thermal (PV/T) system as the research object, this paper studies the design techniques, builds experimental platform of the system and analyzes its thermal and electrical performance. Firstly, the basic architecture parameters of CPC is designed and the key factor which influences the concentrating uniformity of CPC is found via the software named lighttools simulation so that the light distribution uniformity of PV panel is improved. Secondly, the manufacture technique of PV/T collector is designed, including the determination of the size of PV module and the external and internal dimensions of the flat cassette collector. The entire PV/T collector is manufactured by means of direct lamination. Finally, according to the manufactured CPC and PV/T, the experimental platform of CPC integrated PV/T system, whose power is 1kW, is built. The thermal-electrical performance evaluation model of the experimental platform is established. The thermal-electrical performance of the experimental platform is tested and the results show that the water temperature of the outlet can be above 45°C and the total efficiency can reach 60%.

关键词： Solar panels

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Orientation-dependent Hydrodynamic Instabilities from Chemo-Marangoni Cells to Large Scale Interfacial Deformations

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Chinese Journal of Chemical engineering 2007年第5期15卷 748-753页

作者：石英 Kerstin Eckert State Key Laboratory of Multiphase Flow in Power Engineering Xi＇an Jiaotong University Xi＇an 710049 China Institute for Aerospace Engineering Technische Universitat Dresden D-01062 Dresden Germany

The interplay between chemistry and interfacial-tension-driven hydrodynamic instabilities has been studied experimentally. The system on hand consists of two immiscible liquids separated along an initially plane interface at which an interfacial reaction takes place to produce in situ a surfactant. It is identified that the dynamics of the system depends on the orientation of the Hele-Shaw cell with respect to the vector of gravity. If the nele-Shaw cell is placed vertically, Marangoni cells with vigorous convection develop in both phases along a nearly planar interface. However, if the Hele-Shaw cell is tilted off the gravity, the instabilities in the system are characterized by the large scale interracial deformation with a spatio-temporal periodicity together with the chemo-Marangoni convection. The focus is on the exploration of the transition from the cellular mode to the large scale interfacial deformation.

关键词： interfacial reaction in situ produced surfactant Marangoni convection interfacial deformation

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Theoretical investigation on the steady-state natural circulation characteristics of a new type of pressurized water reactor

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Nuclear Science and Techniques 2006年第5期000卷 314-320页

作者： GOU JunLi QIU SuiZheng SU GuangHui JIA DouNan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

This article presents a theoretical investigation on the steady-state natural circulation characteristics of a new type of pressurized water reactor. Through numerically solving the one-dimensional steady-state single-phase conservative equations for the primary circuit and the steady-state two-phase drift-flux conservative equations for the secondary side of the steam generator, the natural circulation characteristics were studied. On the basis of the preliminary calculation analysis, it was found that natural circulation mass flow rate was proportional to the exponential function of the power and that the value of the exponent is related to the operating conditions of the secondary side of the steam generator. The higher the outlet pressure of the secondary side of the steam generator, the higher the primary natural circulation mass flow rate. The larger height difference between the core center and the steam generator center is favorable for the heat removal capacity of the natural circulation.

关键词： Pressurized water reactor Natural circulation characteristics Height difference

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Vortex-In-Cell Simulation of Free Falling Particulate Jet

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Procedia engineering 2015年 102卷 1612-1620页

作者： Rui Wang Bin Chen State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

A two-way coupling three-dimensional Vortex-In-Cell (VIC) method is developed for the simulation of gas-solid turbulent flow. The evolution of vortex elements and the motion of solid particles are tracked in the Lagrangian frame, while the flow field is solved by the vorticity Poisson equation on the Eulerian grid. Two-way coupling is implemented by introducing a vorticity source term induced by the motion of particle. This method is applied to simulate the particulate jet generated by solid particles falling from a circular orifice into unbounded quiescent air. The simulation results agree well with the experiment conducted by Ogata, which confirmed the validation of this method. The simulation results demonstrate that the air velocity radial distribution due to the particulate jet satisfies Gaussian distribution. The particle flow rate has little influence on the spread of particles, while velocity of particles increases with increasing the particle flow rate.

关键词： Votex-In-Cell method Particles Two-way coupling

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Investigation on the impact of the environment wind velocity on the indirect air-cooling tower performance

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AIP Conference Proceedings 2013年第1期1547卷 469-476页

作者： Yongbo Qin Hongfang Gu Haijun Wang Guoyong Chen State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University 710049 Xi'an China

The wind velocity plays a crucial role in the operation characteristic of indirect cooling tower. In this paper a 2×330MW vertical arrangement indirect air-cooled system was taken as research object, and numerical simulation method was used to analyze the relative influence of the wind speed, ranging from 4m/s to 18m/s, on the outlet water temperature of cooling tower, the outlet air temperature of radiator, the facing wind speed of the fan segment and on the outlet air speed of the cooling tower. The result shows that the impact of the natural wind speed on the cooling tower efficiency varies greatly and this impact increases as the wind speed increases.

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Experimental study on pressure drop characteristic of wet air with ash particles in a horizontal tube bundle heat exchanger

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Energy Procedia 2017年 142卷 4010-4015页

作者： Yuanzhi Qin Jingying Yang Haibo Dai Jinshi Wang Ming Liu Junjie Yan State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

The pressure drop characteristic of wet air with ash particles in a horizontal tube bundle heat exchanger was studied experimentally. The variations with time, effects of water vapor mass fractions and mainstream velocities on pressure drop characteristic were presented. Experimentally results showed that with the increase in the time, the pressure drop coefficient firstly increased then became stable. In the case of wet air with ash particles, the pressure drop coefficient increased with the increase of the water mass fraction and decreased with the increase of the mainstream velocity. Compared with wet air without ash particles, the pressure drop coefficients were higher in the presence of ash particles, due to ash deposition.

关键词： Pressure drop coefficient Heat exchanger wet air Ash particles

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Numerical study on annular-mist flow in V-Cone meter for wet gas metering

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AIP Conference Proceedings 2014年第1期1592卷 121-129页

作者： Bofeng Bai Denghui He Rifeng Zhou State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Increasing attention is paid on wet gas flow measurement with V-Cone meter in the production of natural gas. Annular-mist flow is a common flow regime in the wet gas flow metering. Knowledge of the annular-mist flow such as the distributions of the pressure, the droplet and the liquid film in the V-Cone meter is critical to improve the wet gas measurement model. In this paper, a numerical method based on a three-fluid closure model of film, droplet and gas was developed to simulate the annular-mist wet gas flow in the V-Cone meter. The method agreed well with the existing correlation and the relative error of simulation data is less than ±2.5%. The distributions of the droplet, liquid film and static pressure in a V-cone meter and the results on different flow conditions were simulated with the present method. The simulations showed that under the adjustment of the V-Cone element, the droplets moved in a straight path close to the wall after the throat section and a liquid jet was formed. It continues through the diffuser and reattaches to the wall. Some droplets will re-coalescence in the downstream of the V-Cone. It was found that little droplet was entrained in the back of the V-Cone, which was benefit for obtaining the low pressure. The results of the liquid film distribution showed that the liquid film thickness on the pipe wall and the cone body was affected by both the geometry of the V-Cone and the area and strength of the low pressure domain. The pressure in the low pressure domain decreased with the liquid and gas velocity increasing, and the gas-to-liquid viscosity ratio had little effects on the pressure distribution. The downstream low pressure port justifiably locates at six or more pipe diameters downstream of the cone back face for the present V-Cone meter.

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Fatigue Lifetime Estimation of a Heater in Coal-Fired power Plants Under a Flexible Operational Framework-Regulating Extraction Steam of High-Pressure Heaters

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Energy Procedia 2019年 158卷 5225-5230页

作者： Yongliang Zhao Peipei Fan Ming Liu Daotong Chong Junjie Yan State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

Although rapid load variation of coal-fired power plants has become a prior objective for improving the operational flexibility, it will cause a lifetime reduction of heaters due to alternating stresses during transient processes. In the paper, among four flexible regulating measures, the dynamic characteristics of thermal parameters were obtained by GSE software, and thermo-mechanical stresses of 1# high-pressure (HP) heater were calculated by Finite Element Analysis, then the fatigue lifetimes of 1# HP heater were estimated and compared. It turns out that the most stressed position is at water chamber baffle, the allowable numbers of cycles at four measures are 5913-9419, and fatigue damage ratios for per cycle are 0.0106-0.0169%. The study can provide a detailed reference for operators to ensure the operational security of coal-fired power plants within flexibility frameworks.

关键词： Fatigue lifetime estimation thermo-mechanical stress dynamic simulation coal-fired power plant

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Efficient electroreduction of NO 3 - to NH 3 via the tandem catalysis of CeO x /B-Cu 2 O NWs

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Applied Catalysis B: Environment and Energy 2025年 378卷

作者： Zhimin Yao Changzheng Lin Jiaxiang Gao Jiangtao Feng Mingtao Li Wei Yan Wenlong Zhang Hongjie Wang Hebei Key Laboratory of Close-to-Nature Restoration Technology of Wetlands School of Eco-Environment Hebei University Baoding 071002 China Department of Environmental Science & Engineering School of Energy and Power Engineering Xi’an Jiaotong University 28 Xianning West Road Xi’an 710049 China International Research Center for Renewable Energy (IRCRE) State Key Laboratory of Multiphase Flow in Power Engineering (MFPE) Xi’an Jiaotong University 28 Xianning West Road Xi’an 710049 China Engineering Research Center of Ecological Safety and Conservation in Beijing-Tianjin-Hebei (Xiong’an New Area) of MOE China

Electrocatalytic nitrate reduction (eNitRR) has emerged as a carbon-free method for sustainable ammonia synthesis and wastewater treatment. However, the complex reaction intermediates and sluggish hydrogenation kinetics remain the key barriers of eNitRR. Herein, this work presented tandem catalysis strategy and developed a B-doped Cu 2 O nanowires decorated with CeO x to address the two critical issues. Our work presents a high-performance CeO x /B-Cu 2 O NWs catalyst for eNitRR, achieving an ammonia yield of 2.137 mmol h −1 cm −2 and a Faraday efficiency of 98.8 %, which are superior to those of most previously reported catalysts. At a voltage of −0.5 V vs. RHE, cyclic tests with 8 cycles verified the exceptional stability of the catalyst. In-depth in-situ characterization and density functional theory (DFT) computations demonstrated that doping with boron (B) enhances the adsorption of *NO 3 due to the interactions between metallic and non-metallic components. Subsequently, the incorporation of CeO x modifies the electronic structure of Cu 2 O, thereby promoting hydrolysis and ensuring a sufficient supply of active hydrogen. Moreover, we report the successful development of an innovative Zn-NO 3 battery, demonstrating remarkable performance characteristics with an open-circuit voltage of 1.182 V and an exceptional peak power density reaching 21.91 mW cm −2 . Furthermore, by integrating eNitRR with an air stripping process, we successfully recovered high-purity NH 4 Cl products, providing a practical pathway for converting nitrate in wastewater into valuable ammonia-based products. This work provides comprehensive insights into the mechanism of tandem catalysis for eNitRR through the B doping and CeO x heterostructure.

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