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Prediction of thermal performance of radiative radial fin with temperature-dependent thermal conductivity using spectral collocation method

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Journal of Computational and Theoretical Nanoscience 2016年第9期13卷 5822-5831页

作者： Ma, Jing Sun, Ya-Song Li, Ben-Wen Key Laboratory of Shaanxi Province for Development and Application of New Transportation Energy School of Automobile Chang'an University Xi'an710064 China Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy North China Electric Power University Beijing102206 China Institute of Thermal Engineering School of Energy and Power Engineering Dalian University of Technology Dalian116024 China

Spectral collocation method (SCM) is developed to solve coupled radiation and conduction in radiative radial fin with temperature-dependent thermal conductivity and volumetric heat generation. In this approach, energy conservation equation is discretized by SCM, and a particular algorithm is proposed to alleviate the nonlinearity of energy conservation equation. Numerical results by SCM are compared with available results in the literature, which indicate that SCM can provide high accuracy for combined radiative and conductive heat transfer in radiative radial fin, and the integral averaged relative error decreases exponentially with the increasing number of collocation points. Meanwhile, the effects of various parameters on the thermal performance, such as dimensionless thermal conductivity coefficient, radiation-conduction parameter, dimensionless ambient temperature, dimensionless radiation sink temperature and dimensionless volumetric heat generation are also investigated. Copyright © 2016 American Scientific Publishers All rights reserved.

关键词： Fins (heat exchange)

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Free surface vortex in a rotating barrel with rods of different heights

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International Journal of Fluid Machinery and Systems 2016年第4期9卷 325-331页

作者： Zhang, Xiaoyue Zhang, Min Chen, Wanyu Yang, Fan Guo, Xueyan School of Energy and Power Engineering University of Shanghai for Science and Technology No. 516 Jungong Road Shanghai200093 China Department of Mechanical and Electrical Engineering Henan Mechanical and Electrical Engineering College No. 699 Pingyuan Road Xinxiang453003 China Key Laboratory of Flow Control and Simulation University of Shanghai for Science and Technology No. 516 Jungong Road Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering No. 516 Jungong Road Shanghai200093 China

A bathtub vortex above the outlet of a rotating barrel is simulated. By analyzing the Ekman layer theory, it can be found that the main flow circulation is inversely proportional to the thickness of Ekman layer. The thicker the Ekman boundary layer, the weaker the rotational strength and the shorter of the length of gas core is. According to this law, models of barriers with rods of different heights are established. The reduction of air-core length in this air entrainment vortex and weakening the strength of rotation field were achieved. © 2016 Turbomachinery Society of Japan. All rights reserved.

关键词： Vortex flow

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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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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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Influence of Geometrical Structure on Inertial Focusing of Particle in the Microchannel

Influence of Geometrical Structure on Inertial Focusing of P...

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2016年大连国际微纳流体和微流控芯片大会(2016 International Conference of Microfluidics, Nanofluidics and Lab-On-A-Chip

作者： Liang-Liang Fan Hong Zhao Qing Yan Jing Guo Liang Zhao Jiang Zhe Fuli School of Food Equipment Engineering and Science (FEES) Xi ''an Jiaotong UniversityXi ''an P.R.China State Key Laboratory of Multiphase Flow in Power Engineering Xi''an Jiaotong UniversityXi ''an P.R.China Department of Mechanical Engineering University of Akron Akron OH USA

Particles subjected to the inertial lift force will be focused in several equilibrium positions in *** to now, most research on inertial focusing of particles have been focused on the microchannel with a constant cros...

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An experimental study on flow characteristics of homogeneous and stratified debris beds 16

An experimental study on flow characteristics of homogeneous...

引用

16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2015

作者： Li, Liangxing Zou, Xumao Lou, Jiaojiao Li, Huixiong Lei, Xianliang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xian-ning West Road 28# Xi'an city710049 China

ISBN: (纸本)9781510811843

This paper is concerned with reducing uncertainty in quantification of debris bed coolability in a severe accident of light water reactors (LWRs). The experimental results on the flow characteristics of particulate homogeneous and stratified beds are reported here and the objective is to get an idea of how the particles bed characteristics (such as the stratified information and its hierarchical arrangement) affects its flow resistance which is crucially important to the debris bed coolability analysis. Three type beds are packed in a cylindrical test section with the inner diameter of 120 mm and the height of 600 mm. Type-1 bed is homogeneous bed packed with single size spheres. Type-2 bed is also a homogeneous bed with uniformly mixing by two sizes of spheres. Type-3 bed is the axially stratified bed which is composed of two sizes of glass spheres same as that in the Type-2 bed. Both single and two phase flow tests are carried out, the pressure gradients and its flow characteristics are measured and recorded during the tests. The results show that for gas-water co-current flow through a homogeneous bed, the predictions of Reed's model are more comparable with the measured pressure drops. For a bed packed with uniform mixture of particles, the measured pressure gradients are close to the predictions of Ergun equation with area mean diameter at low flowrate (e.g. Rep © Copyright (2015) by American Nuclcar Society All rights reserved.

关键词： Pressure drop

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Experimental study on enrichment of low concentration coal bed methane with solar energy

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2015年第12期36卷 2637-2640页

作者： Yu, Hao-Tian Li, Na Zhou, Qu-Lan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

A large number of low concentration methane gas is emitted directly into the atmosphere during the coal production, resulting in a serious waste of energy and the greenhouse effect. Aiming at the shortcomings of conventional coal mine methane enrichment technology existed, the papar presented separation and enrichment coal mine methane with the Soret effect. The theoretical analysis proposed the main parameters of the enrichment process is the initial methane concentrations and the temperature gradient. The effect law of these parameters is studied by experiments and numerical simulations. © 2015, Science Press. All right reserved.

关键词： Coal

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Effect of groove size on heat transfer performance of loop heat pipe with flat evaporator

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2015年第3期36卷 611-614页

作者： Lü, Xiao Wei, Jin-Jia Long, Yan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

The effect of groove size on heat transfer performance of a loop heat pipe (LHP) with flat evaporator was investigated experimentally, and the comparison of two different kinds of groove size was conducted under different title angles and fluid charging ratios. The results showed that the minimum start-up heat load is same under the same conditions for two different grooves of 2 mm×1.5 mm and 1 mm×1 mm (hight × width), but the former has shorter start-up and transient times. After running steadily, the former has smaller temperature oscillation and lower operating temperature than the latter except for the fluid charging ratio of 55% and the heat load less than 150 W. With increasing heat load, the former has a smaller change in temperature than the latter and the temperature oscillation decreases. As for the heat transfer performance, the thermal resistance decreases with increasing heat load and then levels off for the two different grooves. When the LHP under horizontal position with working fluid charging ratio of 55%, a larger thermal resistance appears for the former initially, and it decreases dramatically with the increase of heat load, and the minimum value of 0.12℃/W is achieved at the heat load of 215 W. © 2015, Science Press. All right reserved.

关键词： Thermal load

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