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2nd International Conference on Machinery, Materials Science and Energy engineering (ICMMSEE)

作者： Ran, Lingyuan Zhao, Jun Qin, Hongbo Hu, Shougen Tian, Xiaolin Univ Shanghai Sci & Technol Power Bldg Shanghai Peoples R China Shanghai Energy Conservat Serv Ctr Shanghai Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

ISBN: (纸本)9783038352280

The flow in centrifugal fan and 90 degrees bend pipe was simulated numerically by the RNG k-turbulent model in software Fluent, and obtained the distribution diagram of the pressure and velocity. From the distribution diagram of the pressure and velocity, for measurement, three measurement points must be chosen, and two of them should be closed to the wall of pipe. However, in order to insure the measure accuracy, five or six measure points should be chosen. In addition, the velocity distribution of pipe bending reaches well-distibuted at the 1000 mm away from pipe exports. That is fluid flowing after through the flow field of bending section tends to uniform soon, so for the greater curvature bend pipe, measurement is more convenient.

关键词： centrifugal fan 90 degrees bend pipe RNG k-epsilon turbulent model Fluent measurement analysis flow field analysis

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Three-dimensional steady calculation on two-phase flow in secondary side of steam generator

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Hedongli Gongcheng/Nuclear power engineering 2014年第2期35卷 37-40页

作者： Cong, Tenglong Tian, Wenxi Qiu, Suizheng Su, Guanghui Xie, Yongcheng Yao, Yangui Department of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Shanghai Nuclear Engineering Research and Design Institute Shanghai 200233 China

Secondary side two-phase flow in steam generator was simulated based on the porous media model. Additional momentum and energy source terms were appended to the momentum and energy equations of porous media region, respectively. The additional momentum source contained the resistances of downcomer, tube bundle, support plate and separator. The additional energy source included the heat transfer from primary side to secondary side fluid. Solving the control equations by ANSYS FLUENT solvers yielded the distributions of velocity, temperature, pressure, density and quality. The distributions of velocity, void fraction and mixture density in hot side vary significantly from these in cold side;the void fraction at the inlet of separator differs from 0.63 to 0.98;pressure descends along axial direction, while at the positions of support plates, pressure declines sharply.

关键词： Porous materials

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Optimization of crucial parameters for double-layer microchannel heat sink

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2014年第3期35卷 567-570页

作者： Lin, Lin Chen, Yang-Yang Wang, Xiao-Dong School of Mechanical Engineering University of Science and Technology Beijing Beijing 100083 China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing 102206 China Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy North China Electric Power University Beijing 102206 China

As compared with single-layer microchannel heat sink (SL-MCHS), double-layer microchannel heat sink (DL-MCHS) can significantly improve the temperature uniformity of electric elements. This work uses a three-dimensional solid-fluid conjugate model incorporated with a progressive optimization procedure to optimize the cooling performance of a water-cooled, silicon-based DL-MCHS. Four geometric parameters (channel number N, bottom channel height Hc1, upper channel height Hc2, and vertical rib width Wr) and coolant velocity ratio of upper channel to bottom channel, t, are selected as optimized variables. The results show that at a fixed pumping power of 0.05 W and a heat fluxes qw=100 W·cm-2, the optimal geometric structure and coolant velocity ratio for the DL-MCHS are Nopt=70, Hc1,opt=200 μm, Hc2,opt=650 μm, Wr,opt=71.48 μm, and topt=1.85. The thermal resistance of the optimal DL-MCHS is reduced by 11.3% compared to the SL-MCHS, and the maximum temperature difference is reduced to 0.5 K, which is far less than 4.2 K of the SL-MCHS.

关键词： heat resistance

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Aerodynamic performance and characteristic of vortex structures for Darrieus wind turbine. II. The relationship between vortex structure and aerodynamic performance

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JOURNAL OF RENEWABLE AND SUSTAINABLE ENERGY 2014年第4期6卷 043135-043135页

作者： Sun, Xiaojing Wang, Ying An, Qimeng Cao, Yang Wu, Guoqing Huang, Diangui Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Shanghai Univ Shanghai Inst Appl Math & Mech Shanghai 200072 Peoples R China Nantong Univ Sch Mech Engn Nantong 226019 Peoples R China

In this paper, transient computational fluid dynamics (CFD) simulations of a straight-bladed Darrieus type vertical axis wind turbine were performed by means of an in-house CFD code. The Spalart-Allmaras turbulence model was implemented in the numerical code for the turbulence. Particular emphasis was placed on effect of interaction between vortices and blades on the aerodynamic performance of the simulated turbine at different tip speed and solidity ratios. The obtained results suggested that vortices were shed from previous blade passages and the close encounter of a rotor blade with these vortices can have a considerable impact on power coefficient of the simulated turbine during operation at different tip speed ratios. As a result, possible reasons for the changes in the behavior of this type of turbine due to the variation of tip speed ratio and solidity were proposed. (C) 2014 AIP Publishing LLC.

关键词： Rotating flows Wind turbines Aerodynamics Channel flows flow simulations

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Evolution of nanofluid rayleigh-bénard flows between two parallel plates: A mesoscopic modeling study

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Journal of Nanotechnology in engineering and Medicine 2013年第4期4卷 040905页

作者： Lu, Gui Duan, Yuan-Yuan Wang, Xiao-Dong Key Laboratory for Thermal Science and Power Engineering MOE Tsinghua University Beijing 100084 China Institute of Thermal Engineering Beijing Jiaotong University Beijing 100044 China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing 102206 China Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy North China Electric Power University Beijing 102206 China

The developing and developed nanofluid Rayleigh-Bénard flows between two parallel plates was simulated using the mesoscopic thermal lattice-Boltzmann method (LBM). The coupled effects of the thermal conductivity and the dynamic viscosity on the evolution of Rayleigh-Bénard flows were examined using different particle volume fractions (1-4%), while the individual effects of the thermal conductivity and the dynamic viscosity were tested using various particle sizes (11 nm, 20 nm, and 30 nm) and nanoparticle types (Al 2O3, Cu, and CuO2). Two different heating modes were also considered. The results show that Rayleigh-Bénard cell in nanofluids is significantly different from that in pure fluids. The stable convection cells in nanofluids come from the expansion and shedding of an initial vortex pair, while the flow begins suddenly in pure water when the Rayleigh number reaches a critical value. Therefore, the average Nusselt number increases gradually for nanofluids but sharply for pure liquids. Uniform fully developed flow cells with fewer but larger vortex pairs are generated with the bottom heating with nanofluids than with pure liquid, with extremely tiny vortexes confined near the top heating plate for top heating. The number of vortex pairs decreases with increasing nanoparticle volume fraction and particle diameter due to the increasing of dynamic viscosity. The average Nusselt number increases with the increasing Rayleigh number, while decreases with the increasing nanoparticle diameters. The nanoparticle types have little effect on the Rayleigh-Bénard flow patterns. The Rayleigh-Bénard flows are more sensitive with the dynamic viscosity than the thermal conductivity of nanofluids. Copyright © 2013 by ASME.

关键词： Nanoparticles

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Simulation of a solar tower thermal power plant using TRNSYS

Simulation of a solar tower thermal power plant using TRNSYS

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26th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2013

作者： Yang, Yan Zhang, Fan Cao, Fei Zhao, Liang Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China Shanghai Electric Power Generation Group Co. Ltd. Shanghai China

The solar tower thermal power technology is a method to achieve the large-scale utilization of solar energy. A user defined TYPE of the heat receiver for the solar tower thermal power plant (STTPP) is established in the TRNSYS program with Fortran codes. Full-year simulation of the STTPP is investigated based on different input parameters, weather conditions and plant control strategies by taking Beijing as a case study. Through this case, the influences of the receiver diameter, flow form and inlet/outlet temperature on the thermal efficiency, total pump power, power efficiency and 'solar-thermal-electricity' transfer efficiency are studied. Simulation results show that the thermal efficiency of receiver rises with the decrease of pipe diameter. The lower the inlet temperature is;the lower the annual pump power consumption is, and the higher the power efficiency would be. An instantaneous increase of the receiver outlet temperature would reduce the power efficiency. The plant control strategies suggest that the "south-in-north-out" arrangement of the heat receiver working fluid holds the highest power efficiency but lowest annual pump power consumption. The annual power generation increases effectively by introducing the hot and cold molten salt storage tanks. The annual power efficiency increases with the power plant capacity.

关键词： Electric power utilization

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Influence of Triggered Seed Bubbles on flow Boiling in Microchannels

Influence of Triggered Seed Bubbles on Flow Boiling in Micro...

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2013 International Conference on Materials engineering and Mechanical Automation(MEMA 2013)

作者： Luxiang zong Jinliang Xu State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy North China Electric Power University

Combined with a simple phase change model,the Volume of Fluid(VOF)method is used for simulating the seed bubble triggered boiling in a single circular microchannel with 6.5mm *** results show that the introduction of seed bubbles improves the heat transfer performance and suppresses the flow instability *** seed bubbles are triggered into the microchannel for f=2000 Hz,passing by only about five numbers of periods,the wall superheats remarkably decreased,a complete thermal equilibrium between the liquid and vapor phases is approached,the flow instability can be controlled *** the stable flow stage,the heat transfer which can reach more than 3 times the single liquid phase heat transfer dominated by the local liquid film thickness,which is the actual heat transfer length-scale in the liquid film ***,the liquid bridge region existing between the bubbles produces a week heat transfer mechanism.

关键词： Seed bubble Microchannel Boiling flow Volume of Fluid(VOF) Method Simulation

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Vertically oriented TiO_2 nanotube arrays with different anodization times for enhanced boiling heat transfer

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Science China(Technological Sciences) 2012年第8期55卷 2184-2190页

作者： XU Jia YANG MingJie XU JinLiang JI XianBing Beijing Key Laboratory of Low-Grade Energy Multiphase Flow and Heat Transfer School of Renewable EnergyNorth China Electric Power UniversityBeijing 102206China Laboratory of Advanced Materials Department of Material Science and EngineeringTsinghua UniversityBeijing 100084China

Pool boiling of saturated water on a plain Ti surface and surfaces covered with vertically-oriented TiO2 nanotube arrays(NTAs) has been *** technique of potentiostatic anodization using non-aqueous electrolytes was adopted to fabricate three types of TiO2 NTAs distinguished by their anodization *** to the bare Ti surface,the incipient boiling wall superheat on the TiO2 NTAs was decreased by 11 *** the critical heat flux and heat transfer coefficient of pool boiling on the TiO2 NTAs were higher than those from boiling on a bare Ti *** measured maximum critical heat flux and heat transfer coefficient values were 186.7 W/cm2 and 6.22 W/cm2K,*** performances for the enhancement of heat transfer by the three types of TiO2 NTAs were attributed to the different degrees of deformation in the nanostructure during ***-term performance of the nanomaterial-coated surfaces for enhanced pool boiling showed degradation of the TiO2 NTAs prepared with an anodization time of 3 hours.

关键词： TiO2 nanotube arrays pool boiling heat transfer enhancement deformation of nanostructure

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Hydrodynamic analysis and calculation of metal temperature distribution in spiral water wall of ultra supercritical tower boiler

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AIP Conference Proceedings 2013年第1期1547卷

作者： Chengwu Shen Dong Yang Danhua Yao Yufeng Zhu Xueyuan Xu State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University China Shanghai Boiler Works Ltd. Shanghai China

In this paper, the spiral water wall system of a 1000MW ultra supercritical tower boiler is simplified as a network system, consisting of circuits, pressure grids and connecting tubes. The establishment of the mathematical model for calculating the mass flux distribution and metal temperature in water wall is based on the mass, momentum and energy conservation equations. The water wall flow distribution and temperature profile of the boiler were computed. The result shows that the differences of outlet temperature and mass flux are small in spiral tube water wall at BMCR, 75%BMCR load and 40%BMCR load. The metal temperatures are all in the allowable ranger.

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Rapid calculation for density of water and steam on p-T thermodynamic surface

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Yingyong Jichu yu Gongcheng Kexue Xuebao/Journal of Basic Science and engineering 2012年第SUPPL.期20卷 190-198页

作者： An, Bin Wang, Xiaodong Duan, Yuanyuan Wang, Zhixue State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing 102206 China Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy North China Electric Power University Beijing 102206 China Key Laboratory for Thermal Science and Power Engineering of MOE Department of Thermal Engineering Tsinghua University Beijing 100084 China

This paper develops a rapid calculation method for thermodynamic properties of water and steam on p-T thermodynamic surface with 273.16K

关键词： Steam

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