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Experimental study of heat transfer of ultra-supercritical pressure water in vertical upward internally ribbed tube

High Technology Letters 2007年第1期13卷 17-22页

作者：王为术 Chen Tingkuan Luo Yushan　 Gu Hongfang Yin Fei National Key Laboratory of Multiphase Flow in Power Engineering Xi＇ an Jiaotong University Xi＇ an 710049 P.R. China School of Power Electric North China Institute of Water Conservancy and Hydroelectric Power Zhengzhou 450011 P.R. China

Under ultra-supercritical pressure, the heat transfer characteristics of water in vertical upward 4- head internally ribbed tubes with a diameter of 28.65mm and thickness of 8mm were experimentally studied. The experiments were performed at P = 25- 34MPa, G = 450- 1800kg/（m^2·s） and q = 200 600kW/m^2. The results show that the pressure has only a moderate effect on the heat transfer of uhra-supercritical water when the water temperature is below the pseudocritical point. Sharp rise of the wall temperature near the pesudocritical region occurs earlier at a higher pressure. Increasing the mass velocity improves the heat transfer with a much stronger effect below the pesudocritical point than that above the pesudocritical point. For given pressure and mass velocity, the inner wall heat flux also shows a significant effect on the inner wall temperature, with a higher inner wall heat flux leading to a higher inner wall temperature. Increasing of inner wall heat flux leads to an early occurrence of sharp rise of the wall temperature. Correlations of heat transfer coefficients are also presented for vertical upward internally ribbed tubes.

关键词： heat transfer supercritieal ultra-supereritieal vertical upward internally fibbed tube

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Natural convection heat transfer of water in a horizontal circular gap

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中国高等学校学术文摘·能源与动力工程 2007年第2期1卷 167-173页

作者： SU Guanghui Kenichiro Sugiyama WU Yingwei State Key Laboratory of Multiphase Flow in Power Emgineering Xi'an jiaotong University Xi'an 710049China Faculty of Engineering Hoddaido University North Ward Sapporo 060-8628Japan

An experimental study on the natural convection heat transfer on a horizontal downward facing heated surface in a water gap was carried out under atmospheric pressure conditions. A total of 700 experimental data points were correlated using Rayleigh versus Nusselt number in various forms, based on different independent variables. The effects of different characteristic lengths and film temperatures were discussed. The results show that the buoyancy force acts as a resistance force for natural convecti on beat transfer ona downward facing horizontal heated surface in a confined space. For the estimation of the natural convection heat transfer under the present conditions, empirical correlations in which Nusselt number is expressed as a function of the Rayleigh number, or both Rayleigh and Prandtl numbers, may be used. When it is accurately predicted, the Nusselt number is expressed as a function of the Rayleigh and Prandtl numbers, as well as the gap width-to-heated surface diameter ratio; and uses the temperature difference between the heated surface and the ambient fluid in the definition of Rayleigh number. The characteristic length is the gap size and the film temperature is the average fluid temperature.

关键词： natural convection downward facing heated surface gap size buoyancy force

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Hydrogen production from sludge in supercritical water and its energy evaluation

Hydrogen production from sludge in supercritical water and i...

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5th International Energy Conversion engineering Conference

作者： Qinming, Zhang Shuzhong, Wang Liang, Wang Donghai, Xu Lingling, Lu State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Department of Thermal Engineering Xi'an Jiaotong University AIAA

ISBN: (纸本)1563479028

Gasification of high moisture content biomass in supercritical water has been identified as a promising alternative system for producing renewable hydrogen. Supercritical water partial oxidation is the process by which an oxidant appears during the reaction. The key advantage of this process is the rapid heating of the gasification medium, resulting in less char formation and improved hydrogen yield. Many researchers have studied the supercritical water gasification of model compounds. However, real biomass which is of importance for large production of hydrogen has yet to be thoroughly examined. In this paper, gasification of high moisture content municipal sludge was studied in a continuous reactor employing hydrogen peroxide as an oxygen source. The reaction was tested across temperatures and pressures in the range of 673 to 873 K and 24 to 30 MPa, and across various residence times ranging from 3 to 15 minutes. We found that sludge at low concentrations can be completely gasified with no observable char or tar formation. The improvement of gasification efficiency by partial oxidation was accompanied with a high yield of hydrogen and carbon monoxide. Through this, we evaluated the energy efficiency of sludge gasification. Our thermodynamic calculations show that the energy efficiency reaches 50% when considering hydrogen, carbon monoxide, and methane as the valuable gases in the ideal case. Taking into account the energy recovery from the hot water at 30 MPa and 873 K and assuming the ideal scenario of no external heat loss, the overall energy yield potentially reaches 85%. Our results show that the key mechanism of the gasification process is energy recovery, as the chemical reaction is endothermic and requires high temperatures.

关键词： Hydrogen production

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New revised correlation to predict pressure drop for oil-gas two-phase flow through horizontal pipe

New revised correlation to predict pressure drop for oil-gas...

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International Petroleum Technology Conference 2007, IPTC 2007

作者： Liu, Wenhong Guo, Liejin Zhang, Ximin Lin, Kai Yang, Long Feng, Yaorong Tubular Goods Research Center of CNPC Key Laboratory for Mechanical and Environmental Behavior of Tubular Goods China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University China

ISBN: (纸本)9781615673360

An experimental investigation on oil-gas two-phase flow through a straight horizontal plexiglas pipe within 40mm inner diameter was conducted. The superficial velocity ranges of oil and air were 0.05-0.612m/s and 0.024-50.64m/s, respectively. The atmospheric temperature condition was maintained throughout the *** frictional pressure drop multiplier of two-phase flow was expressed using the Lockhart-Martinelli parameter correlation in accordance with typical flow pattern, but the modification factor C in the correlations was defined afresh according to flow conditions. New predict correlations for pressure gradient in accordance with typical flow patterns were proposed and the mechanisms of pressure drop production were analyzed for each flow patterns. The proposed models give a good agreement with the experimental data. Copyright 2007, International Petroleum Technology Conference.

关键词： Two phase flow

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Effects of geometric parameters on steady laminar heal transfer in wavy channels

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Jisuan Wuli/Chinese Journal of Computational Physics 2007年第2期24卷 192-196页

作者： Xie, Gongnan Wang, Qiuwang Zeng, Min Luo, Laiqin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 110049 China

Periodically fully developed convective heat transfer characteristics in a two-dimensional wavy channel are investigated numerically with a constant wall temperature. The calculations are performed with Pr=0.7, Re=20-500 on non-orthogonal non-staggered grids generated by an elliptic equation system. A semi-implicit method for pressure linked equations revised (SIMPLER) algorithm in curvilinear body-fitted coordinates is employed. Effects of Reynolds number and geometric parameters, such as aspect ratio φ and shape ratio γ, on heat transfer and friction factor are studied. It shows that no recirculation region occurs through the whole channel at low Reynolds numbers, small aspect ratio or small shape ratio. With the increase of Reynolds number, aspect ratio or shape ratio, heat transfer is enhanced due to flow recirculation. Corresponding friction factor increases simultaneously.

关键词： Heat convection

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Method for liquid viscosity coefficient measurement using inclined tube

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2007年第3期28卷 382-384页

作者： He, Mao-Gang Zhang, Ying Wang, Xiao-Fei Zhong, Qiu Li, Hui-Zhen State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

In this paper, we provide a method which can be used to measure the viscosity coefficient of the liquid under high-pressure condition and low-boil substances using inclined tube, and measurement system was designed and constructed. The kinematic viscosity coefficients of pure water which is the standard substance to calibrate viscosity measurement system were measured to verify the accuracy and reliability of the experimental system. The measurement results show that the absolute average of relative deviations is 0.65%. Then the kinematic viscosity coefficients of the saturated liquid of the low-boil substance, R134a were also measured to detect the measurement system.

关键词： Viscosity

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New Method of Online Measurement of Oil and Suspended Material Concentration In flowing Waste Water

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AIP Conference Proceedings 2007年第1期914卷 215-220页

作者： Hongwei Liao Guobing Xu Xinqiang Xu Fangde Zhou Key State Laboratory of Multiphase Flow and Power engineering Xian Jiaotong University Xian China

At present, the most of the measurements of oil and suspended material concentration in waste water measuring are not online surveys. A new method of online measurement of oil and suspended material concentration in flowing waste water is presented. The room experiments and field tests showed that it is suitable to waste water treatment on line. After sampling, It needed to measure immediately the concentration in first time. Then let sample to be in still in 10 – 20 seconds. After that the bulk concentration was measured in second time. Because of the suspended solids having heavy density, they would be dropped from waster water. During ultrasonic operation, emulsify the oil in waster water, the oil and suspended solid would be depart. After that the third time measurement was done. In thus way the concentrations of oil and suspended solids can be measured. At present there are two on‐site equipments operating in the Changqing oilfield, and the results are pretty well.

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Application of high resolution finite difference scheme in direct numerical simulation of turbulent flow

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2007年第5期28卷 859-861页

作者： Ma, Liang-Dong Li, Zeng-Yao Tao, Wen-Quan State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 China

A direct numerical simulation of a fully developed turbulent flow and heat transfer in a square duct is studied based on high resolution finite difference scheme. The flow and temperature fields are obtained at a turbulent Reynolds number of 400 based on the mean friction velocity and the hydraulic diameter, and the Prandtl number (Pr) of 0.71. Two kinds of point-stencil method are used for the spatial derivatives of the pressure Poisson equation, i.e. the second-order and fourth-order central difference, respectively. The results show that satisfactory solutions can be obtained in the present DNS simulation with coarse grids compared with the method of second-order central difference. And the solutions from the two kinds of point-stencil method for pressure Poisson equation are consistent with the second-order central difference being more economical in saving computation time.

关键词： Pipe flow

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A novel design of the collector's cover of solar induced convection power plant

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International Solar Energy Society Solar World Congress 2007, ISES 2007

作者： Li, Ping Mei, Danhua Li, Zaoyang Chen, Weixiong Zhang, Yongzhi Zhao, Liang School of Energy and Power Engineering Xi'an Jiaotong University P.O. Box 2264 Xi'an 710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

ISBN: (纸本)9781622765447

Solar Induced Convection power Plant is a technology of new energy using. It has a very broad perspective. However, the efficiency of the technology not so acceptable. This paper focuses on improving the efficiency of the technology. The thermal physical properties of common glass, polycarbonate and polycarbonate with CO2 ware compared in this paper to study the superiority and scientificity of polycarbonate with CO2. The results show that, the heat transfer coefficient of polycarbonate with CO2 is the smallest so that it has the best effect of warm-keeping. and it can improve the efficiency of the system to large extent. According to the study, the polycarbonate with CO2 is the best one for solar radiation to go through and it is not easy for Far Infrared ray to do that. Base on the results and other advantages of the polycarbonate with CO2, we conclude that polycarbonate with CO2 is the best choice for the material of the slope solar collector cover.

关键词： Polycarbonates

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Orientation-dependent Hydrodynamic Instabilities from Chemo-Marangoni Cells to Large Scale Interfacial Deformations

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Chinese Journal of Chemical engineering 2007年第5期15卷 748-753页

作者：石英 Kerstin Eckert State Key Laboratory of Multiphase Flow in Power Engineering Xi＇an Jiaotong University Xi＇an 710049 China Institute for Aerospace Engineering Technische Universitat Dresden D-01062 Dresden Germany

The interplay between chemistry and interfacial-tension-driven hydrodynamic instabilities has been studied experimentally. The system on hand consists of two immiscible liquids separated along an initially plane interface at which an interfacial reaction takes place to produce in situ a surfactant. It is identified that the dynamics of the system depends on the orientation of the Hele-Shaw cell with respect to the vector of gravity. If the nele-Shaw cell is placed vertically, Marangoni cells with vigorous convection develop in both phases along a nearly planar interface. However, if the Hele-Shaw cell is tilted off the gravity, the instabilities in the system are characterized by the large scale interracial deformation with a spatio-temporal periodicity together with the chemo-Marangoni convection. The focus is on the exploration of the transition from the cellular mode to the large scale interfacial deformation.

关键词： interfacial reaction in situ produced surfactant Marangoni convection interfacial deformation

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