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Study on the heat transfer of cross flow in vertical upward tubes

Journal of Zhejiang University-Science A(Applied Physics & engineering) 2005年第10期6卷 1128-1131页

作者：胡志华杨燕华周芳德 School of Mechanical Engineering Shanghai Jiao Tong University Shanghai 200030 China State Key Laboratory of Multiphase Flow Xi’an Jiaotong Univeristy Xi’an 710049 China

A special device was designed to measure temperature difference in this study of heat transfer of water and oil cross flow inside vertical upward tubes. A new heat transfer correlation was obtained for cross flow. The experimental results showed that the dependence of heat transfer on Reynolds is much smaller in a narrow space than that in a wide space. It was found that the heat transfer correlation of cross flow in a narrow space is obviously different from that in a wide space, and that the heat transfer correlation obtained in a wide space may not be applicable to the cross-flow heat transfer in a narrow space. Further, the single-phase heat transfer capability of water cross flow was compared with that of oil cross flow. The experimental results showed that the average heat transfer coefficient of water is about 2～3 times that ofoil when they have the same superficial velocity.

关键词： Heat transfer Cross flow Upward

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Thermal boundary condition for the thermal lattice Boltzmann equation

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Physical Review E 2005年第1期72卷 016703-016703页

作者： G. H. Tang W. Q. Tao Y. L. He State Key Laboratory of Multiphase Flow School of Energy and Power Engineering Xi’an Jiaotong University Xi’an Shaanxi 710049 China

A thermal boundary condition for a double-population thermal lattice Boltzmann equation (TLBE) is introduced and numerically demonstrated. The unknown distribution population at the boundary node is decomposed into its equilibrium part and nonequilibrium parts, and then the nonequilibrium part is approximated with a first-order extrapolation of the nonequilibrium part of the populations at the neighboring fluid nodes. Numerical tests with Dirichlet and Neumann boundary constraints show that the numerical results of the TLBE together with the present boundary schemes agree well with the analytical solutions and those of the finite-volume method.

关键词： NAVIER-STOKES EQUATION BGK MODEL HEAT-TRANSFER GAS AUTOMATA flowS SIMULATION PRESSURE VELOCITY

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Gas slippage effect on microscale porous flow using the lattice Boltzmann method

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Physical Review E 2005年第5期72卷 056301-056301页

作者： G. H. Tang W. Q. Tao Y. L. He State Key Laboratory of Multiphase Flow School of Energy and Power Engineering Xi’an Jiaotong University Xi’an Shaanxi 710049 China

A lattice Boltzmann method is developed for gaseous slip flow at the pore scale in microscale porous geometries. flow characteristics through various porous structures are studied for different Knudsen numbers and inlet to outlet pressure ratios. It is found that the gas permeability is larger than the absolute permeability of porous media due to the gas slippage effect. Furthermore, the rarefaction influence on the gas permeability is more evident for porous structures with low porosity. The Klinkenberg equation is confirmed for the simulated porous structures. However, the second-order term of the Knudsen number (Kn2) cannot be neglected for gaseous flow with relatively high Knudsen numbers. A model for predicting the pressure drop of the flow through microscale porous media is presented based on the Ergun equation and the Carman-Kozeny equation by taking into account the effects of gas rarefaction and compressibility.

关键词： MEDIA PERMEABILITY SIMULATION FLUIDS MODEL MICROCHANNELS EQUATION

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Experimental study of the hydrogen production from coal/CMC gasified in super critical water by continuous flow thermal-catalytic reaction system

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Taiyangneng Xuebao/Acta Energiae Solaris Sinica 2005年第6期26卷 874-877页

作者： Yan, Qiuhui Guo, Liejin Liang, Xing Zhang, Ximin Hao, Xiaohong Ma, Lijing State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

As coal was transported homogeneously at high pressure by adding the sodium carboxymethylcellulose (CMC), the hydrogen production from catalytic gasification of coal/CMC in supercritical water (SCW) was investigated. The experimental results showed that the molar fraction of hydrogen is higher than that in conventional gasification. H2, CO2 and CH4 are the main product gases, the higher pressure and higher CMC content is advantage of hydrogen production. Longer residence time is favorite to gasification of coal/CMC, but it is not advantage of hydrogen production from coal/CMC gasified in SCW at 20-25 MPa, 15-30 s and 650°C.

关键词： Hydrogen

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Probabilistic distribution of initial ejection state of particles in equilibrium sand transport

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2005年第4期26卷 613-616页

作者： Xing, Mao Guo, Lie-Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The equilibrium sand transport is simulated by Lagrange model combined with the probabilistic distributions of initial speed and angle of ejection sand grain in this paper. Five forms of the possible distributions are summarized from the previous study results published in literature. Since the macro-quantities simulated by rational distribution should be coincident well with experimental result, the rationality of the distributions can be tested by comparing the quantities simulated from these distributions with the experimental quantities. Detailed analysis indicates that the distribution of initial speed and angle of ejected grains in equilibrium sand transport should be a monotonous decline function. According to the experimental data a segmented function comprised by an exponential distribution and a normal distribution is suggested in this paper. This distributions is confirmed by further comparison with experimental data.

关键词： Distribution Ejection Equilibrium transport Sand

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Investigation on heat transfer characteristics of spiral wall with internal rib in supercritical sliding-pressure operation once-through boiler

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical engineering 2005年第16期25卷 90-95页

作者： Tang, Ren-Hu Yin, Fei Chen, Ting-Kuan National Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Within the range of pressures from 9 to 28 MPa, mass velocities from 600 to 1200 kg/(m2s), and heat fluxes from 200 to 500 kW/m2, experiments have been performed to investigate the heat transfer to water in the inclined upward internally ribbed tube with the inclined angle of 19.5 degree, the maximum outer diameter of 38.1 mm, and the thickness of 7.5 mm. Based on the experiments, it was found that heat transfer enhancement of the internally ribbed tube could postpone departure from nucleate boiling at the sub-critical pressure. However, the heat transfer enhancement decreased near the critical pressure. At supercritical pressure, the temperature difference between the wall and fluid increased near the pseudo-critical temperature, but the increasing of wall temperature was less than that of departure from nucleate boiling at sub-critical pressure. When pressure was close to the critical pressure, the temperature difference between the wall and fluid greatly increased near the pseudo-critical temperature. Heat transfer to supercritical water in the inclined upward internally ribbed tube was enhanced or deteriorated near the pseudo-critical temperature with the variety of ratio between the mass velocity and the heat flux. Due to the rotational flow of the internal groove reducing the effect of nature convection, the internal wall temperature of the inclined upward internally ribbed tube uniformly distributed along the circumference. The maximum internal wall temperature difference of the inclined upward internally ribbed tube along the circumference was only 10 degree Centigrade when the fluid enthalpy exceeds 2000 kJ/kg. Considering the effect of acute variety of the fluid property on heat transfer, the correlation of heat transfer coefficient on the top of the inclined upward internally ribbed tube have been provided.

关键词： Boilers

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Study on dryout point in vertical narrow annuli

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Nuclear Science and Techniques/Hewuli 2005年第1期000卷

作者： TIAN Wen-xi AYE Myint QIU Sui-zheng JIA Dou-nan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an710049

Prediction of dryout point is experimentally investigated with deionized water upflowing through narrow annular channel with 1.0 mm and 1.5 mm gap respectively. The annulus with narrow gap is bilaterally heated by AC current power supply. The experimental conditions covered a range of pressure from 0.8 to 3.5 MPa, mass flux of 26.6 to 68.8 kg·m-2·s-1 and wall heat flux of 5 to 50 kW·m-2. The location of dryout is obtained by observing a sudden rise in surface temperature. Kutateladze correlation is cited and modified to predict the location of dryout and proved to be not a proper one. Considering in detail the effects of geometry of annuli, pressure, mass flux and heat flux on dryout, an empirical correction is finally developed to predict dryout point in narrow annular gap under low flow condition, which has a good agreement with experimental data.

关键词： Narrow annular channel Bilaterally heating Dryout point Critical quality Annular flow

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Economic performance analysis and heat exchange calculating in the system of storage ice by spraying water in winter

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Yingyong Jichu yu Gongcheng Kexue Xuebao/Journal of Basic Science and engineering 2005年第SUPPL.期13卷 177-183页

作者： Liu, Weimin Bi, Qincheng Guo, Yajun Dong, Mingxiao Zhang, Linhua Gao, Feng State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China School of Environmental and Municipal Eng. Xi'an University of Architecture and Technology Xi'an 710049 China Shandong Institute of Architecture and Engineering Jinan 250014 China

The system of ice-making by spraying water in winter and utilizing the ice in summer is pollution-free and economizes the first investment, operating cost, and reduces the peak of electric power in summer. Through establishing the energy equilibrium equation of sprayed water drop, the relation between the diameter of water droplet and the time of icing at different ambient temperature and coefficient of performance of the system of ice-making by spraying water has been obtained. The errors between the numerical solution and the experimental data lie in a range of 7% to 10%, indicating that the model is reasonable. The method of the ice making is promising in the exercisable region to substitute the mechanical refrigeration system.

关键词： Cold storage

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A mathematical model and numerical simulation of pressure wave in horizontal gas-liquid bubbly flow

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自然科学进展（英文版） 2004年第4期14卷 344-349页

作者： HUANG Fei BAI Bofeng Guo Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

By using an ensemble-averaged two-fluid model,with valid closure conditions of interfacial momentum exchange due to virtual mass force,viscous shear stress and drag force,a model for pressure wave propagation in a horizontal gas-liquid bubbly flow is *** to the small perturbation theory and solvable condition of one-order linear uniform equations,a dispersion equation of pressure wave is *** pressure wave speed calculated from the model is compared and in good agreement with existing *** to the dispersion equation,the propagation and attenuation of pressure wave are investigated *** factors affecting pressure wave,such as void fraction,pressure,wall shear stress,perturbation frequency,virtual mass force and drag force,are *** result shows that the decrease in system pressure,the increase in void fraction and the existence of wall shear stress,will cause a decrease in pressure wave speed and an increase in the attenuation coefficient in the horizontal gas-liquid bubbly *** effects of perturbation frequency,virtual mass and drag force on pressure wave in the horizontal gas-liquid bubbly flow at low perturbation frequency are different from that at high perturbation frequency.

关键词： pressure wave two-fluid model gas-liquid bubbly flow dispersion speed attenuation

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Dryout point prediction model for bilaterally heated vertical narrow annuli under low flow conditions

Dryout point prediction model for bilaterally heated vertica...

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25th Annual CNS Conference - Nuclear Energy: Meeting the Challenges

作者： Myint, Aye Tian, Wenxi Li, Zhihui Hao, Li Jia, Dounan State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University No.28 Xianning West Road Xi'an City 710049 China

ISBN: (纸本)0919784798

Prediction of dryout point was experimentally investigated with deionized water upflowing through narrow annular channel with 1.0 mm and 1.5 mm gap respectively. The annular with narrow gap was bilaterally heated by AC current power supply. The experimental conditions covered a range of pressure from 0.8 to 3.5 MPa, mass flux of 60.39 to 135.6 kg/m2 and heat flux of 5 to 50 kW/m2 This paper presents a new analytical model for the prediction of dryout point for steam- water flow in narrow annular gap and bilaterally and uniformly heated tubes. The prediction of dryout point for bilaterally heated annuli was based on the droplet-diffusion model for internally heated annuli by Kirillov and Smogalev (1969, 1972). The dryout model prediction values are compared with a experimental data, showing a good agreement in accuracy for the above mentioned parametric range.

关键词： Nuclear power plants

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