multiphaseflow measurement, desanding, dehumidification and heat furnace are critical techniques for the oil and gas gathering and transportation, which influnce intensively the energy‐saving and emission‐reduction...
multiphaseflow measurement, desanding, dehumidification and heat furnace are critical techniques for the oil and gas gathering and transportation, which influnce intensively the energy‐saving and emission‐reduction in the petroleum industry. Some innovative techniques were developed for the first time by the present research team, including an online recognation instrument of multiphaseflow regime, a water fraction instrument for multuphase flow, a coiled tube desanding separator with low pressure loss and high efficiency, a supersonic swirling natural gas dehumifier, and a vacuum phase‐change boiler. With an integration of the above techniques, a new oil gas gathering and transpotation system was proposed, which reduced the establishment of one metering station and several transfer stations compared with the tranditional system. The oil and gas mixture transpotation in single pipes was realized. The improved techniques were applied in the oilfields in China and promoted the productivity of the oilfields by low energy consumption, low emissions, high efficiency and great security.
The shrinking core model(SCM) is widely used to model fluid‐solid reaction in many studies. Based on the shrinking core model incorporated particle size distribution(PSD) and the characteristic of products, a modifie...
The shrinking core model(SCM) is widely used to model fluid‐solid reaction in many studies. Based on the shrinking core model incorporated particle size distribution(PSD) and the characteristic of products, a modified model has been set to simulate the reaction process of fluid and solid. Limestone dissolution is a typical liquid‐solid reaction, and experimental work has been done with five kinds of limestone from different producing area in china. The dissolution process of limestone can be predicted. In the model, two parameters the comprehensive reaction coefficient k and total reaction rate constant km are defined. By chosen proper value, the model can well describe the limestone dissolution process in acid. Furthermore, km is dependent of mass transfer in fluid and chemical reaction but independent of properties of solid and fluid. k and km can be deduced from experimental results by numerical method, and km is similar for different samples with the same reaction condition. The model established a relationship between micro parameter and macro experimental data.
flow and temperature fields during the solidification of hypereutectic and hypoeutectic NH4Cl‐H2O solution in rectangular cavities were measured by a particle image velocimetry(PIV) and a weak perturbation thermocoup...
flow and temperature fields during the solidification of hypereutectic and hypoeutectic NH4Cl‐H2O solution in rectangular cavities were measured by a particle image velocimetry(PIV) and a weak perturbation thermocouple network, respectively. Double‐diffusive convections caused by the coupling effects of temperature and solute gradients were studied by the experiment. During the solidification of hypereutectic solution, the rejected water near the solidification interface will lead to dilute solute layers and double‐diffusive interfaces. As the continued rejection of water, the layer and interface will evolve into instability and a multi‐layer and multi‐interface structure will be formed. To the hypoeutectic solution, the rejection of NH4Cl near the solidification interface will form a dense solute layer. When the thickness of the dense solute layer is large enough, the coupling effects of stabilizing solute gradient and unstable temperature gradient will lead to new solute layers. The solute layers and double‐diffusive interfaces will evolve stably and have no breakup of the double‐diffusive interfaces during the solidification of hypoeutectic solution.
Cold stimuli evoke more rapid transient pain sensations in human teeth than hot ***, the underlying mechanism remains *** has been reported that hot stimuli cause an inward flow (toward the tooth pulp chamber) of the ...
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Cold stimuli evoke more rapid transient pain sensations in human teeth than hot ***, the underlying mechanism remains *** has been reported that hot stimuli cause an inward flow (toward the tooth pulp chamber) of the dentinal fluid in dentinal microtubules while cold stimuli cause flow in a reverse *** study attempts to quantify tooth pain sensation by coupling a computational fluid dynamics (CFD) model, which describes the fluid mechanics in dentinal microtubules, with a modified Hodgkin-Huxley (H-H) model, which describes the neural discharge behavior.
A model coupling two basic models, the model with interface tracking method and two‐fluid model, for simulation of incompressible gas‐liquid two‐phase flow is proposed. A united solution frame shared by the two bas...
A model coupling two basic models, the model with interface tracking method and two‐fluid model, for simulation of incompressible gas‐liquid two‐phase flow is proposed. A united solution frame shared by the two basic models is built. In the shared solution frame, the Navier—Stokes equations of the two basic models can be dealt with in a uniform form. In the proposed model, there are three phases, which are divided not only by physics but also by the length scale of interface, including the liquid phase, the large‐length‐scale‐interface gas phase and the small‐length‐scale‐interface gas phase. The special treatment named by “void fraction redistribution” is adopted for the special grids which contain all three phases. Based on the united solution frame, MCBA—SIMPLE algorithm is used to solve the equations. Two problems are calculated to show that the proposed model has the merits of the two basic models.
In the gas/solid twophase system, particles can accumulate a large number of electrostatic charges because of the collision, friction and separation between particles or between particles and wall. When particles movi...
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The dynamic characteristics of molten droplets and hot particles at the very beginning of their fall into coolant pools are presented. The falling course of a single droplet or a single hot particle was recorded by a ...
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The dynamic characteristics of molten droplets and hot particles at the very beginning of their fall into coolant pools are presented. The falling course of a single droplet or a single hot particle was recorded by a highspeed camera and a curve of velocity vs. time was obtained. Emphasis was placed on the effects of the droplet's size and temperature, the coolant's temperature and properties, and the droplet's physical properties on the moving behavior. The results for the all cases showed that the velocity of a falling droplet/particle decreased rapidly but rebounded shortly, at the beginning of droplet/particle falling in the coolant. Following such a V-shaped evolution in velocity, the droplet/particle slows down gradually to a comparatively steady velocity. An increase in either coolant temperature or droplet temperature results in a larger velocity variation in the 'J-region', but a smaller deceleration when it moves out of the 'J-region'. The elevated volatility of a coolant leads to a steeper deceleration in the 'J-region' and beyond. The bigger size of a particle leads to a greater velocity variation in the 'J-region' and terminal velocity. A high melting point and thermal conductivity as well as lower heat capacity contribute to dramatic variation in the 'J-region' and low terminal velocity.
The moving particle semi-implicit method (MPS) was used to simulate the typical free surface problem, 2D dam break problem, and the effect of initial particle configuration on the simulated results was analyzed. It is...
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The moving particle semi-implicit method (MPS) was used to simulate the typical free surface problem, 2D dam break problem, and the effect of initial particle configuration on the simulated results was analyzed. It is found that the reasonable results can not be achieved for too large or too small particle distance. The comparison of the results by MPS, SPH or VOF with the experimental data shows that the result by MPS is between those by VOF and by SPH. Without the consideration of viscosity, the result by MPS is closer to the experiment than that by VOF. However, the result by MPS with the consideration of viscosity may be similar to that by SPH.
The principal pressure drop in a subsea riser is generally the gravitational pressure drop component due to liquid holdup. Surfactant is a kind of Chemical compound related to flow improvement. Gas‐liquid two‐phase ...
The principal pressure drop in a subsea riser is generally the gravitational pressure drop component due to liquid holdup. Surfactant is a kind of Chemical compound related to flow improvement. Gas‐liquid two‐phase flow in subsea riser with zero and small liquid flow rates was simulated in two vertical tubes with diameters of 40 mm and 65 mm, respectively. Liquid holdup reduction of subsea riser was investigated with surfactant. The simulation was conducted at low pressure, using air as the gas phase and water as the liquid phase. Pressure drop was measured by using differential pressure transducer and holdup was obtained by trapping the liquid in the pipe section. Different trace amounts of surfactant were used in this vertical two‐phase flow system. The liquid holdups were measured at different surfactant concentrations and different gas‐liquid flow ratios. Liquid holdups with and without surfactant additives are compared and analyzed. How the foamer influences the two‐phase flow pattern was observed and the range of foamer concentration corresponding to the best holdup reduction was obtained.
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