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Heat transfer and pressure drop characteristics of condensation for R410A in a 3.78mm circular tube under normal and micro gravity

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ASME 2016 Heat Transfer Summer Conference, HT 2016, collocated with the ASME 2016 Fluids engineering Division Summer Meeting and the ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels

作者： Zhang, Jingzhi Shih, Tom I.-P. Shi, Yanping Li, Wei Zhang, Yonghai Niu, Yuzhen Department of Energy Engineering Zhejiang University Hangzhou Zhejiang China Department of Energy Engineering Collaborative Innovation Center of Advanced Aero-Engine Zhejiang University Hangzhou Zhejiang China School of Aeronautics and Astronautics Purdue University West LafayetteIN47907 United States Shanxi FTEC Engineering Co. Ltd. Taiyuan Shanxi China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shanxi China Hangzhou Fortune Group Co. Ltd. Hangzhou Zhejiang China

ISBN: (纸本)9780791850336

Heat transfer and pressure drop characteristics of condensation for R410A inside horizontal tubes (dh=3.78 mm) under normal and micro gravity are investigated numerically. The Volume of Fluid method is used to acquire liquid-vapor interface, while the low-Reynolds form of the Shear Stress Transport k∼ω (SST k∼ω) model is adopted to taking turbulent effect into account. The results indicate that the heat transfer coefficients decrease with increasing gravity accelerations, while the frictional pressure gradients increase with increases in gravity accelerations. The liquid film accumulates at the bottom of the tube, leading to a very thin liquid film attached to the upper part of inner tube wall. This accumulation effect decreases with decreases in gravitational accelerations. A more symmetrical liquid-vapor interface is obtained at lower gravity. The average liquid film thickness is nearly the same for different gravity accelerations at the same vapor quality (8ave=56 μm at x=0.9 and 8ave=230 μm at x=0.5). The local heat transfer coefficients increase with increasing gravity at the top of the tube and decrease with increases in gravity at the bottom, while the bottom part of the tube has a limited contribution to the global heat transfer coefficient for stratified flow regime. The numerical data obtained under normal gravity agree well with well-known empirical correlations. Copyright © 2016 by ASME.

关键词： Condensation

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Dicyanovinyl-unit-induced absorption enhancement of iridium(III) complexes in long-wavelength range and potential application in dye-sensitized solar cells

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Science China Chemistry 2015年第4期58卷 658-665页

作者： Dongdong Wang Hua Dong Xiaoyu Zhang Yong Wu Shaohua Shen Bo Jiao Zhaoxin Wu Min Gao Geng Wang Department of Applied Chemistry School of Science Xi’an Jiaotong University Key Laboratory for Physical Electronics and Devices of the Ministry of Education School of Electronic and information Engineering Xi’An Jiaotong University Key Laboratory for Advanced Materials Institute of Fine Chemicals and Department of Chemistry East China University of Science and Technology International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University

Iridium complexes with dicyanovinyl-grafted phenylpyridine/l-phenylisoquinoline as ligands are synthesized and their photo- physical, electrochemical, and sensitization properties in DSSCs are investigated. The iridium complexes present significantly enhanced absorption from 400 to 525 nm. The 1-phenylisoquinoline-based iridium complex show bathochromic-shift emission in DMSO solution compared with their phenylpyridine-based counterpart, while their absorption response and photoluminescence peak in solid show little difference despite extension of the conjugated system. Using DSSCs, the conversion efficiency of 0.62% and open-circuit current of 1.4 mA/cm2 is achieved. The poor performance is attributed to the excited-state properties of iridium complexes according to the TD-DFT calculation.

关键词： dicyanovinyl group iridium complexes absorption response dye-sensitized solar cell

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Publisher's Note: Numerical investigation of the yawed wake and its effects on the downstream wind turbine [J. Renewable Sustainable Energy 8, 033303 (2016)]

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Journal of Renewable and Sustainable Energy 2016年第5期8卷

作者： Miao, Weipao Li, Chun Yang, Jun Xie, Xiaoyun School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China Laboratory of Fluid and Power Machinery Xihua University Jinniu District Sichuan610000 China Shanghai Behr Thermal Systems Co. Pudong District Shanghai201206 China

This article was originally published online on 9 June 2016 with affiliation 3 incorrectly assigned to the second author. Chun Li is not affiliated with the Lab

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Investigation on flow boiling heat transfer characteristics of water in vertically-upward spirally-ribbed tubes under subcritical pressures

Investigation on flow boiling heat transfer characteristics ...

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International Conference on power engineering, ICOPE 2015

作者： Zhang, Weiqiang Li, Huixiong Zhang, Qing Zhang, Qian Kong, Xiangfei Wu, Jinkai State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xianning West Road 28 Xi'an710049 China

Series of experiments have been performed at different pressures from 12 to 19 MPa, mass velocities from 400 to 1000 kg·m-2· s-1, inner wall heat fluxes from 300 to 500 kW· m-2 and bulk fluid enthalpy from 800 to 3100 kJ·kg1, to study flow boiling heat transfer characteristics of water in seven vertically-upward spirally-ribbed tubes with different rib structures. Based on the experimental results, effects of pressure, mass velocity and heat flux on flow boiling heat transfer coefficient (HTC) were discussed. It was found that, saturated flow boiling HTC was nearly invariable with an increase in mass velocity, but it increased distinctly with the increase in heat flux. As the pressure increased, the flow boiling HTC increased. Some existing correlations for predicting flow boiling HTC of water in the spirally-ribbed tubes were evaluated with the test data collected from open literatures and obtained in this experiment. On the basis of experimental results of flow boiling heat transfer from open literature and internal report, a new universal correlation for the flow boiling HTC of subcritical pressure water was developed for spirally-ribbed tubes with different rib structures, by introducing suitable dimensionless quantities of the spirally-ribbed tube structures to the existing empirical correlations. It was shown that the values calculated by the new correction are in good agreement with the experimental data for the two new-type spirally-ribbed tubes, indicating that the newly proposed universal correlation could provide good support for the application of the vertically-upward spirally-ribbed tubes. © 2015 The Japan Society of Mechanical Engineers.

关键词： Heat flux

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Development of cladding oxidation analysis code [COAC] and application for early stage severe accident simulation of AP1000

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Progress in Nuclear Energy 2015年 85卷 352-365页

作者： Mao, keyou Wang, Jun Li, Longze Zhang, Yapei Tian, Wenxi Su, Guanghui Qiu, Suizheng Corradini, Michael L. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China College of Engineering University of Wisconsin-Madison Madison 53706 United States

Abstract Clad oxidation is an important phenomenon which can affect core degradation under severe accident conditions. The oxidation process always coincides with cladding material embrittlement. The energy released from the oxidation of cladding material can accelerate the accident process, and the hydrogen released from oxidation may threaten the integrity of vessel. As a consequence, the high temperature clad solid-phase oxidation model research and its code development play an important role in reactor safety analysis. To push the research on this region, a clad solid-phase oxidation analysis code (COAC) is developed by Xi'an Jiaotong University. To verify the quality of COAC, CORA-13 is used as a benchmark. The results show that COAC does produce expected values. COAC is then applied to AP1000 severe accident calculations. In this case, the station blackout accident (SBO) is modeled. The response of fuel rods under varying natural circulation conditions while coolant pump idle time is calculated. The calculations show that the oxidation of cladding can delay fracturing, and protect its integrity. Meanwhile, the performances of other oxidation models are explored in this paper. © 2015 Elsevier Ltd.

关键词： AP1000 Clad solid-phase oxidation models COAC Hydrogen generation rate

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Dynamic analysis on methanation reactor using a double-input–multi-output linearized model

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Chinese Journal of Chemical engineering 2015年第2期23卷 389-397页

作者：李星星李佳庚杨伯伦张勇 Department of Chemical Engineering State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Northwest Research Institute of Chemical Industry

A double-input–multi-output linearized system is developed using the state-space method for dynamic analysis of methanation process of coke oven *** stability of reactor alone and reactor with feed-effluent heat exchanger is compared through the dominant poles of the system transfer *** single or double disturbance of temperature and CO concentration at the reactor inlet,typical dynamic behavior in the reactor,including fast concentration response,slow temperature response and inverse response,is revealed for further understanding of the counteraction and synergy effects caused by simultaneous variation of concentration and *** results show that the stability of the reactor loop is more sensitive than that of reactor alone due to the positive heat ***,with the decrease of heat exchange efficiency,the reactor system may display limit cycle behavior for a pair of complex conjugate poles across the imaginary axis.

关键词： Coke oven gas methanation Synthetic natural gas Double-input–multi-output linearized system Dynamic analysis Limit cycle behavior

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Experimental study on liquid nitrogen spray in atmospheric environment 24

Experimental study on liquid nitrogen spray in atmospheric e...

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24th IIR International Congress of Refrigeration, ICR 2015

作者： Xue, Rong Liu, Xiufang Cao, Feng Hou, Yu School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

ISBN: (纸本)9782362150128

In spray cooling system, the liquid coolant is broken into numerous fine droplets through a spray nozzle to cool the target. The liquid nitrogen spray could obtain low cooling temperature and excellent heat transfer performance with phase change in a large temperature difference. It can be widely used in low temperature tunnel cooling, ground simulation environment and laser therapy. The open loop liquid nitrogen spray platform is built to investigate the nitrogen spray characteristics. The solid cone vortex nozzle WL32 (3.18 mm diameter) and fine fog nozzle P66 (1.68 mm diameter) are used in the experiment. The spray pressure differences (0.25MPa to 0.8MPa) are sourced by the high pressure room temperature gas nitrogen and controlled through a manual valve. In the experiment, the spray field is recorded by a high speed camera (HG-100K from Redlake Co.) and the diameter of the spray droplet from WL32 is analyzed through the Malvern Spraytec laser particle size analyzer. The pressure difference between nozzle inlet and outlet has different influence on the spray angle of WL32 and P66. The quantity of spray droplets of WL32 increases with the increasing pressure, which leads to the improvement of the atomizing effect and the decline of Sauter Mean Diameter.

关键词： Liquid nitrogen

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Characterization of heat transfer in R134 - A spray cooling 24

Characterization of heat transfer in R134 - A spray cooling

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24th IIR International Congress of Refrigeration, ICR 2015

作者： Liu, Jionghui Qian, Yang Shuangtao, Chen Hou, Yu Liu, Xiufang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China

ISBN: (纸本)9782362150128

A closed loop spray cooling system with R134 - A as spray medium was used to investigate the performance of spray cooling characteristic. The heat transfer parameters such as heat flux, heat transfer coefficient and target surface temperature were studied under different volumetric flow rate and spray chamber pressure. The single-phase heat transfer region and the phase-change heat transfer region were analyzed at different heat fluxes. The results show that the heat flux, critical heat flux (CHF) and heat transfer coefficient directly relate with volumetric flow rate. The higher flow rate and spray chamber pressure could achieve higher CHF with better heat transfer performance. And the different relationship between heat transfer coefficient and surface temperature was obtained at different spray cooling period.

关键词： Heat flux

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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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Experimental study on pressure oscillation caused by unstable steam jet in subcooled water flow

Experimental study on pressure oscillation caused by unstabl...

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International Conference on power engineering, ICOPE 2015

作者： Yang, Xiao-Ping Chen, Yi Zong, Xiao Liu, Ji-Ping Chong, Dao-Tong Yan, Jun-Jie MOE Key Laboratory of Thermal Fluid Science and Engineering Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

The dominant frequency of pressure oscillation caused by unstable steam jet in subcooled water flow in a narrow channel was experimentally investigated. In this study, a visualized test section with rectangular channel, steam nozzle and water nozzle was designed. A high speed camera was employed to record flow patterns. In order to investigate the characteristics of pressure oscillation in the channel, several high frequency dynamic pressure transducers were arranged on the wall of the channel. The main inlet parameters, including steam mass flux, water mass flux and inlet water temperature were tested in the range of 150-400kg/(m2s), 6-18×103kg/(m2s) and 15-40°C. Two different unstable flow patterns were observed as bubble flow and oscillation jet. The dominant frequency of pressure oscillation under various test conditions was obtained by fast Fourier transform (FFT) method. The results indicated that the dominant frequency was dependent on the variation of condensation length of the steam jet. The longer the condensation length, the lower the dominant frequency. The influence of steam mass flux, water mass flux and inlet water temperature on dominant frequency was discussed. The dominant frequency would decrease with the increase of steam mass flux and inlet water temperature, but increase with the water mass flux. © 2015 The Japan Society of Mechanical Engineers.

关键词： Condensation

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