multiphaseflow induced CO2 corrosion has resulted in serious losses in oil and gas production. In this paper, gas-liquid two-phase vertical upward slug flow has been analyzed from aspects containing flow structure, h...
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multiphaseflow induced CO2 corrosion has resulted in serious losses in oil and gas production. In this paper, gas-liquid two-phase vertical upward slug flow has been analyzed from aspects containing flow structure, hydrodynamic characteristics, mass transfer characteristics and their effects on pipe wall and corrosion product film, and it is found that slug flow has a distinct effect on transports of corroding species to and of corrosion products from the wall, momentum interchange between fluid and wall and the formation and damage of corrosion product film. In addition, the transports of corrosive species and corrosion product are also an important step in CO2 corrosion process. It is assumed that the slug flow induced CO2 corrosion of pipeline is dependent on the non-linear coupling of the characteristics including the shear stress, the normal stress, the mass transfer coefficient, and the electrochemical reaction. [ABSTRACT FROM AUTHOR]
To investigate the mechanism of active control for flow separation in rectangle diffuser by vortex generator jets (VGJs) method, numerical analysis with large-eddy simulation and experimental measurement by particle i...
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The attempt of the author in this research is made to calculate a heat transfer coefficient (HTC) by combining the filmwise theory with the dropwise notion for ethanol-water mixtures condensation. A new model, includi...
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The attempt of the author in this research is made to calculate a heat transfer coefficient (HTC) by combining the filmwise theory with the dropwise notion for ethanol-water mixtures condensation. A new model, including ethanol concentration, vapor pressure and velocity, is developed by introducing a characteristic coefficient to combine the two mentioned-above theories. Under different concentration, pressure and velocity, the calculation is in comparison with experiment. It turns out that the calculation value is in good agreement with the experimental result; the maximal error is within ±30.1%. In addition, the model is applied to calculate related experiment in other literature and the values obtained agree well with results in reference. [ABSTRACT FROM AUTHOR]
ZnS-CuInS2-AgInS2 solid solution photocatalysts were successfully prepared by co-precipitation method with heat treatment under different atmosphere (N2 and H2S). XRD, XRF, UV-vis, and SEM were used to characterize th...
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ZnS-CuInS2-AgInS2 solid solution photocatalysts were successfully prepared by co-precipitation method with heat treatment under different atmosphere (N2 and H2S). XRD, XRF, UV-vis, and SEM were used to characterize the prepared photocatalysts, indicated that the composition of result photocatalysts were different from each other and also the rate of charge, though they possessed a wurtzite-type phase structure. The photocatalysts all showed photocatalytic activities for H2 evolution from aqueous solutions containing SO32- and S2- as sacrificial reagents under visible light irradiation with Ru loading, but sample treated under H2S atmosphere performed better, the possible reason was proposed. [ABSTRACT FROM AUTHOR]
In this article, using Gibson-Ashby constitutive model, we suggest a new method for numerical investigation of forced convection heat transfer in porous foam metal, and try to consolidate the study for mechanical prop...
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In this article, using Gibson-Ashby constitutive model, we suggest a new method for numerical investigation of forced convection heat transfer in porous foam metal, and try to consolidate the study for mechanical property and that for thermal characteristic. By available experimental data, we simulated to two cases, namely as the transfer in porous media for diameter is 0.6 mm and porosity is 0.402, and for diameter is 1.6 mm and porosity is 0.462. The result, from our constitutive model for single forced convection heat transfer, corresponds well with the experimental data. As for pressure drop prediction in porous is in good agreement with experiment, and the error is only 5% to 10%, but for transfer is less accurate, the error is about 20%, which is acceptable in practice. So it is done that constitutive model is used to simulate the transfer property. [ABSTRACT FROM AUTHOR]
Experiments on the condensation of steam jet submerged in the subcooled water were carried out. The water temperature and the inlet steam pressure were in the range of 293 K–343 K and 0.2–0.6 MPa, respectively. Four...
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Experiments on the condensation of steam jet submerged in the subcooled water were carried out. The water temperature and the inlet steam pressure were in the range of 293 K–343 K and 0.2–0.6 MPa, respectively. Four essential shapes of steam plume were enumerated. According to the comparisons of the pictures of steam plume with the graphs in the same size, the pressure came to maximum value in the contraction spots, except for the double expansion-emanative shape. Moreover, pressure distributions of the flow field were characterized by means of drawing isobar. Comparison and discussions on the relationship between steam plume and pressure distributions were given. With the increase of temperature, pressure distributions within steam plume became more complex. Radial pressure distributions were classified according to different regions. Comparisons of the pressure distributions at different water temperature and inlet steam pressure were obtained. [ABSTRACT FROM AUTHOR]
With anionic surfactant LAS assisted, series of zinc cadmium sulfide semiconductor photocatalysts were synthesized by hydrothermal method. These products were characterized by X-ray diffraction (XRD), UV-Vis absorptio...
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With anionic surfactant LAS assisted, series of zinc cadmium sulfide semiconductor photocatalysts were synthesized by hydrothermal method. These products were characterized by X-ray diffraction (XRD), UV-Vis absorption spectra (UV-Vis) and scanning electron microscopy (FESEM). The photocatalytic activities of as-prepared samples were evaluated by photocatalytic hydrogen production from water under visible-light irradiation. The best synthesis parameters are: Composition 0.9:0.1 (Cd:Zn molar ratio), Temperature 160 °C, Hydrothermal Time 48 Hour, LAS Concentration 1.7 mmol/L, the maximum visible-light-catalytic hydrogen production rate is 161.25 μmol/h (λ>430 nm) which is higher than those of by coprecipitation method. The experiment results indicate that surfactant assisted hydrothermal method is an effective way to get highly active CdZnS solid solution photocatalyst. [ABSTRACT FROM AUTHOR]
This paper proposes an improved lattice Boltzmann scheme for incompressible axisymmetric flows. The scheme has the following features. First, it is still within the framework of the standard lattice Boltzmann method u...
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This paper proposes an improved lattice Boltzmann scheme for incompressible axisymmetric flows. The scheme has the following features. First, it is still within the framework of the standard lattice Boltzmann method using the single-particle density distribution function and consistent with the philosophy of the lattice Boltzmann method. Second, the source term of the scheme is simple and contains no velocity gradient terms. Owing to this feature, the scheme is easy to implement. In addition, the singularity problem at the axis can be appropriately handled without affecting an important advantage of the lattice Boltzmann method: the easy treatment of boundary conditions. The scheme is tested by simulating Hagen-Poiseuille flow, three-dimensional Womersley flow, Wheeler benchmark problem in crystal growth, and lid-driven rotational flow in cylindrical cavities. It is found that the numerical results agree well with the analytical solutions and/or the results reported in previous studies.
In this paper, a numerical simulation is performed in order to reveal the evaporation heating transfer mechanism of the falling-film of water on the outer wall of horizontal tubes, and the influence of gas-water-solid...
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In this paper, a numerical simulation is performed in order to reveal the evaporation heating transfer mechanism of the falling-film of water on the outer wall of horizontal tubes, and the influence of gas-water-solid contact angles on the film distribution on the tube is mainly addressed. The simulation is performed by solving the motion equation of the fluid on fixed three-dimensional (3D) grid systems, and the so-called volume of fluid (VOF) method is employed to handle the movement of interface between the liquid and the vapor phase. The numerical results are compared with that of a simplified model and also with the experimental recordings obtained in visualization experiments conducted with tubes made of different materials, and it is shown that the numerical results are in very good agreement with the experimental observation of the falling films, indicating that the numerical methods applied in the present study is correct and accurate. Based on the numerical results, effects of the contact angle, the flow rate, the tube diameter and the liquid feeder height on the falling film behavior are discussed. Generally, the film width increases along with the increase of flow rate or the liquid feeder height, while variation of the film thickness exhibits different features at different conditions, and the contact angle is one of the major factors governing the behavior of the falling films. [ABSTRACT FROM AUTHOR]
Two-dimensional numerical simulation of the deformation and breakup of an isolated liquid drop suspended in immiscible viscous fluid under shear flow was performed with the diffuse interface method. The governing equa...
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Two-dimensional numerical simulation of the deformation and breakup of an isolated liquid drop suspended in immiscible viscous fluid under shear flow was performed with the diffuse interface method. The governing equations of the model were described by Navier—Stokes—Cahn—Hilliard equations. The surface tension was treated as a modified stress. In the paper, the critical Capillary number was plotted as a function of viscosity ratios with the method of approximation. Besides, From the numerical observations, the breakup of the droplets occurred by three mechanisms, namely, necking, end pinching, and capillary instability. Quantitative results for the deformation and breakup of drop are presented. [ABSTRACT FROM AUTHOR]
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