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Experimental Investigations on Boiling Heat Transfer Inside Miniature Circular Tubes Immersed in FC-72

Journal of Thermal Science 2002年第4期11卷 303-307页

作者： Qincheng Bi Tianshou Zhao Yajun Guo Tingkuan Chen State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an710049China Department of Mechanical Engineering The Hong Kong University of Science&TechnologyHong KongChina School of Environmental and Municipal Administration Engineering Xi’an University of Architecture&TechnologyXi’an710055China

To investigate the size effect on the characteristics of boiling heat transfer, boiling behavior of FC-72 in heated vertical miniature circular tubes immersed in a liquid pool was experimentally studied. Two AISI 304 stainless steel tubes with inner diameters of 1.10 mm and 1.55 mm correspondingly, were heated by swirled Ni-Cr wire heaters and sealed in Lucite blocks by silicon adhesive. Both the top and the bottom ends of the circular test sections were open to the liquid pool. The boiling curves and heat transfer coefficients were obtained experimentally. The boiling behaviors at the outlets of the miniature tubes were also visualized with a digital video camera. Experimental results show that the tube geometry has a significant effect on the boiling characteristics. Vapor blocking at the outlet of the smaller circular tube with a diameter of 1.10 mm caused severe boiling hysteresis phenomena. The CHF decreased with reducing in tube size.

关键词： boiling heat transfer pool boiling FC-72 miniature circular tube.

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A NUMERICAL PRESSURE TRANSIENT MODEL FOR MULTILAYERED GAS RESERVOIRS WITH PSEUDOSTEADY STATE FORMATION CROSSflow

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Journal of Hydrodynamics 2002年第2期14卷 71-77页

作者： Sun He-dong, Wang Yue-she, Zhou Fang-de State key laboratory of multiphase flow in power engineering, Xi’an Jiaotong University, Xi’an 710049, China Gao Cheng-tai Xi’an Petroleum Institute, Xi’an 710065, China Zhao Hai-hong China Oil and Gas Pipel State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Xi'an Petroleum Institute Xi'an 710065 China China Oil and Gas Pipeline Scientific Research Institute Langfang 065000 China

Reservoir deposition occurs over geologic periods of time. Although reservoirs are assumed to be homogenous for simplicity of analysis, most reservoirs are heterogeneous in nature. Some common forms of hetergeneity are the presence of layers and the presence of different zones of fluids and/or rock in the formation. A modified semi-permeable model for multi-layered gas reservoirs with pseudo-steady state interlayer crossflow was developed. The model accounted for the effect of skin and wellbore storage, considers all layers open to a single well, which flows at constant total rate. This new numerical solution was proved to be computationally very efficient, and it has been validated by comparing the results with those of some simple, well known models in the well testing literature. The effects of the reservoir parameters such as permeability, vertical permeability, skin, wellbore storage on the wellbore response, pressure and layer production rate were investigated. Numerical solutions of the problem for the modified semi-permeable model were used to find the structure of crossflow in typical cases.

关键词： layered reservoir semi-permeable model transient well testing numerical simulation crossflow

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Distribution of void fraction for gas-liquid slug flow in aninclined pipe

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Nuclear Science and Techniques 2001年第2期12卷 143-148页

作者： XIA Guo-Dong1, ZHOU Fang-De2, HU Ming-Sheng2 (1 College of Environmental and Energy engineering, Beijing Polytechnic University, Beijing 100022 2 State key laboratory of multiphase flow in power engineering, Xi’an Jiaotong University, xi’an 710049) College of Environmental and Energy Engineering Beijing Polytechnic University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

In order to investigate the effect of inclination angle on the spatial distribution of phases, experiments on gas-liquid two-phase slug flow in an inclined pipe were carried out by using the optical probe and an EKTAPRO 1000 high speed motion analyzer. It has been demonstrated that the inclination angle and the mixture velocity are important parameters to influence the distribution of void fraction for upward slug flow in the inclined pipe. At high mixture velocity, the gas phase profile is axial symmetry in the cross-section of the pipe. This is similar to that for vertical slug flow. In contrast, most of the gas phase is located near the upper pipe wall at low mixture velocity. By measuring the axial variation of void fraction along the liquid slug, it can be concluded that there is a high void fraction wake region with length of 3～4D in the front of liquid slug. In the fully developed zone of liquid slug, the peak value of the void fraction is near the upper wall.

关键词：气-液二相流斜管相分布

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Numerical Simulation of Transient 3-D Turbulent Hested Jet into Crossflow in a Thick-Wall T-Junction Pipe

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Journal of Thermal Science 2001年第1期10卷 46-51页

作者： Wu Hailing, Chen Tingkuan, Luo Yushan, Wang Haijun (State key laboratory of multiphase flow in power engineering,Xi’an Jiaotong University, Xi’an 710049, China) State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

The present work is to investigate the transient three-dimensional heated turbulent jet into crossflow in a thickwall T-junction pipe using CFD package. Two cases with the jet-to-crossflow velocity ratio of 0.05 and 0.5 are computed, with a finite-volume method utilizing κ-ε model. Comparison of the steady-state computations with measured data shows good qualitative agreement. Transient process of injection is simulated to examine the thermal shock on the T-junction component. Temporal temperature of the component is acquired by thermal coupling with the fluid. Via analysis of the flow and thermal characteristics, factors causing the thermal shock are studied. Optimal flow rates are discussed to reduce the thermal shock.

关键词： numerical simulation low jet-to-crossflow velocity ratio thick-wall T-junction pipe thermal shock

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Numerical Investigation of Developing Turbulent flow in a Helical Square Ductwith Large Curvature

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Journal of Thermal Science 2001年第1期10卷 1-6页

作者： Gao Hui,Guo Liejin (State key laboratory of multiphase flow in power engineering, Xi’an Jiaotong University, Xi’an 710049, China ) State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

A fully elliptic numerical study has been carried out to investigate the three-dimensional turbulent developing flow in a helical square duct with large curvature. A two-layer zonal model is proposed and used, in which the whole region is divided into a viscosity-affected near wall layer and a fully turbulent region. A DSM closure is applied in the former, and a one-equation model is solved in the latter. The results presented in this paper cover a Reynolds number range of (l- 10) x 104. The development of flow is found to be dominated by radial pressure gradient and Dean-type secondary motion. The distribution of Reynolds stresses in fully developed flow exhibit a complex pattern of turbulence anisotropy The development of peripherally averaged friction factor and the distribution of local friction factor in fully developed flow are given and discussed.

关键词： curved pipe developing flow turbulence model numerical simulation.

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Distribution of void fraction for gas-liquid slug flow in an inclined pipe

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Nuclear Science and Techniques 2001年第2期000卷 143-148页

作者： XIA Guo-Dong ZHOU Fang-De HU Ming-Sheng College of Environmental and Energy Engineering Beijing Polytechnic University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

关键词： Gas-liquid slug flow Void fraction Inclined pipe

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Numerical simulation of strongly swirling turbulent flows in a liquid-liquid hydrocyclone using the Reynolds stress transport equation model

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Science China(Technological Sciences) 2000年第1期43卷 86-96页

作者：陆耀军周力行沈熊 State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Department of Engineering Mechanics Tsinghua University Beijing 100084 China

The Reynolds stress transport equation model (DSM) is used to predict the strongly swirling turbulent flows in a liquid-liquid hydrocyclone, and the predictions are compared with LDV measurements . Predictions properly give the flow behavior observed in experiments, such as the Rankine-vortex structure and double peaks near the inlet region in tangential velocity profile, the downward flow near the wall and upward flow near the core in axial velocity profiles. In the inlet or upstream region of the hydrocyclone, the reverse flow near the axis is well predicted, but in the region with smaller cone angle and cylindrical section, there are some discrepancies between the model predictions and the LDV measurements. Predictions show that the pressure is small in the near-axis region and increases to the maximum near the wall. Both predictions and measurements indicate that the turbulence in hydrocy-clones is inhomogeneous and anisotropic.

关键词： strongly swirling flows numerical simulation hydrocyclone

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Transient convective heat transfer in a helical tube with steam-water two-phase flow under pressure drop type oscillations

Transient convective heat transfer in a helical tube with st...

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ASME 2000 International Mechanical engineering Congress and Exposition, IMECE 2000

作者： Guo, Lie-Jin Feng, Zi-Ping Xi'an Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Province Xi'an710049 China

ISBN: (纸本)9780791826621

In the present paper the experiments for subcooled water flow and steam-water two-phase flow were conducted to investigate the effects of pulsation upon transient heat transfer characteristics in a closed-circulation helical-coiled tube steam generator. The non-uniform property of local heat transfer with steady flow was also examined. The secondary flow mechanism and the effect of interaction between the flow oscillation and secondary flow were analyzed cm the basis of the experimental data. Some new phenomena were observed and explained. A series of correlations were proposed for the average and local heat transfer coefficients both under steady and oscillatory flow conditions. The results showed that there were considerable variations in local and peripherally time-averaged Nusselt numbers for pulsating flow in a wide range of parameters. Systematic investigations of pressure drop type oscillations and their thresholds for steam-water two-phase flow in a uniformly heated helical tube were also reported. Copyright © 2000 by ASME

关键词： Drops

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Turbulent heat transfer in a horizontal helically coiled tube

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Heat Transfer 2000年第5期28卷

作者： Bofeng Bai Liejin Guo Ziping Feng Xuejun Chen State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University China

An experiment has been conducted in detail to study the turbulent heat transfer in horizontal helically coiled tubes over a wide range of experimental parameters. We found that the enhancement of heat transfer in the coils results from the effects of turbulent and secondary flows. With Reynolds number increasing to a high level, the contribution of the secondary flow becomes less to enhance heat transfer, and the average heat transfer coefficient of the coil is closer to that in straight tubes under the same conditions. The local heat transfer coefficients are not evenly distributed along both the tube axis and the periphery on the cross section. The local heat transfer coefficients on the outside are three or four times those on the inside, which is half of the average heat transfer. A correlation is proposed to describe the distribution of the heat transfer coefficients at a cross section. The average cross-section heat transfer coefficients are distributed along the tube axis. The average value at the outlet section should not be taken as the average heat transfer coefficient. © 1999 Scripta Technica, Heat Trans Asian Res, 28(5): 395–403, 1999

关键词： turbulent heat transfer horizontal helically coiled tube secondary flow local heat transfer

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Experimental Study on the Characteristics of Liquid Layer and Disturbance Waves in Horizontal Annular flow

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Journal of Thermal Science 1999年第4期8卷 235-242页

作者： Li Weidong Zhou Fangde Li Rongxian Zhou Lixing Department of Engineering Mechanics Tsinghua UniversityBeijing 100084China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

The mechanism for transporting liquid from the bottom of the pipe to the top still to be established in the prediction of the film thickness distribution in horizontal annular two-phase flow. To resolve this issue, using five parallel-wire conductance probes, time records of local liquid film thickness at five circumferential positions were collected. The characteristics of circumferential liquid film thickness profiles and its variation with gas and liquid velocities were obtained. The basic features of probability distribution function, probability density function, auto-correlation, cross-correlation and power spectrum density function of the disturbance waves in angular flow were studied respectively. The characteristics of circumferential profiles of disturbance waves and its variation with gas and liquid velocities were presented.

关键词： two-phase flow annular flow liquid layer disturbance wares.

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