In-situ fluid phase behavior is important in determining hydrocarbon contents and the multiphase flow through shale reservoirs.The gas-to-oil ratio(GOR) has been recognized as a critical indicator of fluid types.Howev...In-situ fluid phase behavior is important in determining hydrocarbon contents and the multiphase flow through shale reservoirs.The gas-to-oil ratio(GOR) has been recognized as a critical indicator of fluid types.However,little is known about the impact of fluid phase variation across the thermal maturity on shale oil/gas production(e.g.,estimated ultimate recovery,EUR).According to the specific gravity ratio of oil/gas,the producing GOR was converted and normalized into a mass fraction of gas in total hydrocarbons(MGOR) to compare North American shale oil/gas plays with Chinese shale oil and hybrid gas-condensate plays.A correlation between MGOR,the fluid phases,and production data was established to identify five phase stages of flow.MGORvaries systematically with the different production zones,which shows promise in rapidly indicating the well production performance and high production stages of shale oil/gas plays.The hybrid shale gas condensate index,Tmax,and total gas contents were integrated to present the fluid types and maturity of shale gas-condensates,which indicates fluid phase and production variation across thermal evolution.The results offer a unique perspective on the shale oil reservoir producibility based on the impact of GOR on fluid phases and EUR from the dominant global oil/gas plays.展开更多
This work mainly studies the effect of fluid phase momentum transfer mechanisms on the acidizing results,including the retardation effect of the porous structure and the interaction between the fluid phase,such as vis...This work mainly studies the effect of fluid phase momentum transfer mechanisms on the acidizing results,including the retardation effect of the porous structure and the interaction between the fluid phase,such as viscous dissipation and inertial effect.The results show that the acid fluid momentum transfer is influenced by the complex porous structure and fluid viscous dissipation.Eventually,the Stokes-Darcy equation is recommended to be adopted to describe the fluid phase momentum transfer in the following numerical simulation studies of the carbonate acidizing process.Based on this model,a parametric research is carried out to investigate the impact of acid on rock physical characteristics in the stimulation process.Increasing the acid concentration appears to minimize the quantity of acid consumed for the breakthrough.The acid surface reaction rate has a considerable impact on the pore volume to breakthrough and the optimum acid injection rate.The influence of permeability on the acidizing results basically shows a negative correlation with the injection rate.The difference between the acidizing curves of different permeability gradually becomes insignificant with the decrease in injection rate.The existence of isolated fracture and vug significantly reduces acid consumption for the breakthrough.展开更多
Based on the fluid phase equilibrium of the C-O-H system, the compositions of var-ious fluid phases under high temperatures and pressures have been calculated in terms of the available thermodynamic data and new P-V-T...Based on the fluid phase equilibrium of the C-O-H system, the compositions of var-ious fluid phases under high temperatures and pressures have been calculated in terms of the available thermodynamic data and new P-V-T data and on the assumption of PT = ΣPi in this paper. The results indicate that in this system there are 5 major fluid phases in different pro-portions at various T and P. CH4 is the dominant phase (about 70% ) under relatively lower T and P. Its proportion obviously decreases with increasing T, P and fo2. The results pro-vide sufficient theoretical grounds for discussing the possibility of CH4 formation and the physical-chemical conditions of its stable occurrence and proportion in the geological environment.展开更多
A phase diagram of argon based upon percolation transition loci determined from literature experimental p-V isotherms, and simulation values using a Lennard-Jones model shows three fluid phases. The liquid phase spans...A phase diagram of argon based upon percolation transition loci determined from literature experimental p-V isotherms, and simulation values using a Lennard-Jones model shows three fluid phases. The liquid phase spans all temperatures, from a metastable amorphous ground state at 0K, to ultra-high T. There is a supercritical mesophase bounded by percolation transition loci, and a gas phase. Intersection of two percolation loci in the p-T plane thermodynamically defines a critical line between two coexisting gas and liquid critical states at T = Tc, and the single mesophase for T > Tc. A debate on the absence of a van der Waals critical point in the Gibbs p-T density surface is appended.展开更多
BZ26-6 Oilfield is a kind of deep metamorphic rock buried-hill volatile oilfield in Bohai Sea, China. Its early development plan is restricted due to the simultaneous production of oil and gas in large sections of res...BZ26-6 Oilfield is a kind of deep metamorphic rock buried-hill volatile oilfield in Bohai Sea, China. Its early development plan is restricted due to the simultaneous production of oil and gas in large sections of reservoirs, unclear understanding of formation fluid properties and uncertainty of gas-oil interface. Through theoretical research on phase recovery and experimental analysis of crude oil phase characteristics in the original formation, characteristic parameters of the equilibrium condensate gas fluid are restored and calculated. Through the superimposed phase diagram of volatile oil and condensate gas, BZ26-6 Oilfield is determined to be a volatile oil reservoir with a condensate gas cap, with formation pressure and saturation pressure of 36.1 MPa, respectively. Based on the research results of oil-gas phase behavior characteristics, the thermodynamic equations and equation of state are jointly used to solve the problem, and the content change curves of each component at different depths are drawn. Combined with the sensitivity analysis of numerical simulation, the gas-oil interface is determined to be -3726 m above sea level. The fluid phase analysis software, Fluidmodeler, is used to simulate volatile oil degassing and condensate gas separation experiments. In combination with oil and gas production data obtained through the production test, the specific oil recovery index and the specific gas recovery index are determined to be 0.408 m<sup>3</sup>/(MPa·d·m) and 1195 m<sup>3</sup>/(MPa·d·m), respectively. And the reasonable production capacity prediction is conducted on the early development of BZ26-6 Oilfield. The research results can provide a theoretical basis for the efficient development of similar complex oil and gas reservoirs.展开更多
The quasi-solid-fluid phase transition of granular materials is closely related to the shear rate and solid concentration in addition to their intrinsic properties. The contact duration and the coordination number are...The quasi-solid-fluid phase transition of granular materials is closely related to the shear rate and solid concentration in addition to their intrinsic properties. The contact duration and the coordination number are two important temporal-spatial parame-ters to describe the granular interaction in phase transition. In this study, characteristics of the contact duration and the coordination number associated with the transition processes are determined using a 3D discrete element model under different shear rates and concentrations. The resulting macroscopic stress and strain-rate relations are discussed. The temporal and spatial parameters provide a linkage between the macroscopic constitutive law and inter- particle micromechanics.展开更多
We have prepared novel coated particles, with a conductor graphite core and a dielectric TiO2 coating, as the dispersed phase of electrorheological fluids. One order of magnitude enhancement in the shear stress is obt...We have prepared novel coated particles, with a conductor graphite core and a dielectric TiO2 coating, as the dispersed phase of electrorheological fluids. One order of magnitude enhancement in the shear stress is obtained by using such composite particles, when it is compared with that of TiO2 particles. The experimental results show a way to get excellent ER system.展开更多
By means of the computational fluid dynamics software Fluent 6.3, a mathematical model of three-dimensional three-phase fluid flow field in the molten bath of electric arc furnace （EAF） with side accessorial oxygen ...By means of the computational fluid dynamics software Fluent 6.3, a mathematical model of three-dimensional three-phase fluid flow field in the molten bath of electric arc furnace （EAF） with side accessorial oxygen lances was developed to study the transient phenomena of oxygen jet impingement on the molten steel and the molten slag. The water modeling experiment was carried out to verify the simulation results. The impingement of the supersonic oxygen jet caused impact dent on the molten steel surface accordingly. The area of impact dent changed almost in linear relationship to flow rate of oxygen jet, which can be expressed by a deduced mathematical equation. And the relationship between the impact force of oxygen iet and the correspondingly formed apparent static pressure on molten bath was obtained, which was in linear relationship and a direct proportion, and can also be expressed by a deduced mathematical equation.展开更多
The USM-θ model of Bingham fluid for dense two-phase turbulent flow was developed, which combines the second-order moment model for two-phase turbulence with the particle kinetic theory for the inter-particle collisi...The USM-θ model of Bingham fluid for dense two-phase turbulent flow was developed, which combines the second-order moment model for two-phase turbulence with the particle kinetic theory for the inter-particle collision. In this model, phases interaction and the extra term of Bingham fluid yield stress are taken into account. An algorithm for USM-θ model in dense two-phase flow was proposed, in which the influence of particle volume fraction is accounted for. This model was used to simulate turbulent flow of Bingham fluid single-phase and dense liquid-particle two-phase in pipe. It is shown USM-θ model has better prediction result than the five-equation model, in which the particle-particle collision is modeled by the particle kinetic theory, while the turbulence of both phase is simulated by the two-equation turbulence model. The USM-θ model was then used to simulate the dense two-phase turbulent up flow of Bingham fluid with particles. With the increasing of the yield stress, the velocities of Bingham and particle decrease near the pipe centre. Comparing the two-phase flow of Bingham-particle with that of liquid-particle, it is found the source term of yield stress has significant effect on flow.展开更多
RH vacuum degasser is a very important secondary refining device in the production of high quality steels. The flow field of molten steel in RH system plays a significant role in determining productivity of the equipm...RH vacuum degasser is a very important secondary refining device in the production of high quality steels. The flow field of molten steel in RH system plays a significant role in determining productivity of the equipment. The homogeneous model and VOF method were often used to predict the flow field in RH system, but these kinds of models simplified the interaction between gas bubbles and molten steel. In the present work, a numerical model of a whole RH system, including vacuum degasser, immersed legs and ladle,was built based on gas-liquid two-fluid model, and it could be used to analyze the interaction between argon bubbles and molten steel, to understand the effect of the bubble size to the flow field.展开更多
A packed column supercritical fluid chromatography (SFC) method for the separation of clopidogrel enantiomers on a chiral stationary phase and CO2 with modifier as mobile phase has been developed at an analytical scal...A packed column supercritical fluid chromatography (SFC) method for the separation of clopidogrel enantiomers on a chiral stationary phase and CO2 with modifier as mobile phase has been developed at an analytical scale. Among 11 different 2 stationary phases the Chiral cel OD-H column showed by far the best separation properties. The influence of different modifiers, injection solvents, temperature, and pressure, and density of the fluid, respectively, on the separation behaviour has been studied. It was found that the separation behaviour strongly depends on the type of modifier and the modifier content. Temperature and pressure are of less influence.展开更多
A flow apparatus was set up for measuring the solubility of a solid solute in a supercritical fluid withthe presence of a small amount of entrainer.The solubilities of biphenyl,diphenylamine and benzoic acid insupercr...A flow apparatus was set up for measuring the solubility of a solid solute in a supercritical fluid withthe presence of a small amount of entrainer.The solubilities of biphenyl,diphenylamine and benzoic acid insupercritical carbon dioxide with one of the selected entrainers which were ethanol,acetone and n-hexanerespectively,were obtained in the pressure range of 10—32 MPa and the temperature range of 308—318K.Asolvolytic association theory has been proposed to explain the mechanism of entrainer effect,and theexperimental results were reasonably analysed.According to the solvolytic association theory,the association equa-tion of state was adopted to correlate the experimental data with good accuracy.展开更多
A mathematical model of two-phase fluid nonlinear flow in the direction of normal of ellipse through low-permeability porous media was established according to a nonlinear flow law expressed in a continuous function w...A mathematical model of two-phase fluid nonlinear flow in the direction of normal of ellipse through low-permeability porous media was established according to a nonlinear flow law expressed in a continuous function with three parameters, a mass conservation law and a concept of turbulent ellipses. A solution to the model was obtained by using a finite difference method and an extrapolation method. Formulas of calculating development index not only before but also after water breaks through an oil well in the condition of two-phase fluid nonlinear flow in the media were derived. An example was discussed. Water saturation distribution was presented. The moving law of drainage front was found. Laws of change of pressure difference with time were recognized. Results show that there is much difference of water saturation distribution between nonlinear flow and linear flow; that drainage front by water moves faster, water breaks through sooner and the index gets worse because of the nonlinear flow; and that dimensionless pressure difference gets larger at the same dimensionless time and difficulty of oil development becomes bigger by the nonlinear flow. Thus, it is necessary that influence of nonlinear flow on development indexes of the oil fields be taken into account. The results provide water-flooding development of the oilfields with scientific basis.展开更多
The dynamics of phase separation in two-dimensional binary fluid with low-middle densities was investigated by molecular dynamics simulation. The spinodal decomposition region for symmetric systems may be divided into...The dynamics of phase separation in two-dimensional binary fluid with low-middle densities was investigated by molecular dynamics simulation. The spinodal decomposition region for symmetric systems may be divided into the diffusive and kinematic region. At an elevated temperature, the motion of particles is diffusive. At a middle temperature, the kinematic mechanism takes effect on the systems with middle density, and the diffusive mechanism holds only for the dilute system. At a low temperature, the phase separation obeys the kinematic mechanism in a wide range of density. For asymmetric systems, the growth of particles A (majority) is different from that of particles B (minority). The diffusive and kinematic regions for the majority are similar to those of symmetric system. The growth exponent for the minority is related to its absolute density and temperature because of its small density.展开更多
Linearized equations of fluid dynamics of cell two phase flow for one dimensional case are proposed. Based on the equations, an analytic solution is derived, in which the frequency of wave is observed. The frequency f...Linearized equations of fluid dynamics of cell two phase flow for one dimensional case are proposed. Based on the equations, an analytic solution is derived, in which the frequency of wave is observed. The frequency formula consists of all important parameters of the fluid dynamics. In our observation, the group velocity and phase velocity of the motion of wave propagation are explicitly exhibited as well.展开更多
Based on a lattice Boltzmann method and general principles of porous flow, a numerical technique is presented for analysing the separation of multi-phase immiscible fluids in porous media. The total body force acting ...Based on a lattice Boltzmann method and general principles of porous flow, a numerical technique is presented for analysing the separation of multi-phase immiscible fluids in porous media. The total body force acting on fluid particles is modified by axiding relative permeability in Nithiarasu＇s expression with an axiditional surface tension term. As a test of this model, we simulate the phase separation for the case of two immiscible fluids. The numerical results show that the two coupling relative permeability coefficients K12 and K21 have the same magnitude, so the linear flux-forcing relationships satisfy Onsager reciprocity. Phase separation phenomenon is shown with the time evolution of density distribution and bears a strong similarity to the results obtained from other numerical models and the flows in sands. At the same time, the dynamical rules in this model are local, therefore it can be run on massively parallel computers with well computational efficiency.展开更多
Climate change is a reality. The burning of fossil fuels from oil, natural gas and coal is responsible for much of the pollution and the increase in the planet’s average temperature, which has raised discussions on t...Climate change is a reality. The burning of fossil fuels from oil, natural gas and coal is responsible for much of the pollution and the increase in the planet’s average temperature, which has raised discussions on the subject, given the emergencies related to climate. An energy transition to clean and renewable sources is necessary and urgent, but it will not be quick. In this sense, increasing the efficiency of oil extraction from existing sources is crucial, to avoid waste and the drilling of new wells. The purpose of this work was to add diffusive and dispersive terms to the Buckley-Leverett equation in order to incorporate extra phenomena in the temporal evolution between the water-oil and oil-water transitions in the pipeline. For this, the modified Buckley-Leverett equation was discretized via essentially weighted non-oscillatory schemes, coupled with a three-stage Runge-Kutta and a fourth-order centered finite difference methods. Then, computational simulations were performed and the results showed that new features emerge in the transitions, when compared to classical simulations. For instance, the dispersive term inhibits the diffusive term, adding oscillations, which indicates that the absorption of the fluid by the porous medium occurs in a non-homogeneous manner. Therefore, based on research such as this, decisions can be made regarding the replacement of the porous medium or the insertion of new components to delay the replacement.展开更多
A total of 50 healthy volunteers aged between 18 and 54 years underwent phase-contrast cine MR to assess cerebrospinal fluid flow characteristics in different regions of the vertebral canal. The results revealed that ...A total of 50 healthy volunteers aged between 18 and 54 years underwent phase-contrast cine MR to assess cerebrospinal fluid flow characteristics in different regions of the vertebral canal. The results revealed that the cerebrospinal fluid peak flow velocity and peak flow rate in the systolic phase were significantly greater than those in the diastolic phase at the same level in the subarachnoid space of the cervical spinal canal. The ventral peak flow velocity and peak flow rate were significantly greater than the post-lateral peak flow velocity and flow rate, while there were no differences between left and right post-lateral subarachnoid peak velocity and flow rate. Moreover, there were no significant differences in peak flow velocity and peak flow rate between the systolic and diastolic phases, ventral, right post-lateral or left post-lateral peak flow velocity and peak flow rate at the same level in the subarachnoid space of the cervical spinal canal among different age groups （18 24, 25 34, 35-44, ≥45 years）.展开更多
Modern processing technology is calling the scientific understanding of dynamic processes,where the science of complex fluids plays a central role.We summarize our recent efforts using the generic approaches of multi-...Modern processing technology is calling the scientific understanding of dynamic processes,where the science of complex fluids plays a central role.We summarize our recent efforts using the generic approaches of multi-scale physics of complex fluids on apparently irrelevant processes,i.e.the mixing of polymer blends,the processing of thermoplastic(TP) toughened thermosetting(TS) composites using phase separation of TP in TS,as well as the enhanced oil recovery using polymer soft gel.It is emphasized that the thorough physical understanding in multi-scales of time and space through the joint efforts of experiment and theory in each scale is the key issue for the modeling of various processes.展开更多
Use of the low temperature (less than 100°C) energy contributes to effective use of heat resources. The cost recovery by power generation is difficult by using an existing system (the binary cycle or the thermoel...Use of the low temperature (less than 100°C) energy contributes to effective use of heat resources. The cost recovery by power generation is difficult by using an existing system (the binary cycle or the thermoelectric conversion element), because the initial investment is large. The final purpose of this research is development of the low temperature difference drive engine supposing use in a hot-springs resort as a power source for electric power generation. In order that a traveler may look at and delight a motion of an engine, it is made to drive at low-speed number of rotations. An engine cycle of this study is aimed at the development of Stirling cycle engine which can maintain high efficiency in small size. This kind of engine has simple structure;it brings low cost, and it is easy to perform maintenance. However, it is difficult to obtain enough output by this type of engine, because of its low temperature difference. This paper deals with the heat transfer characteristic that the working fluid including a phase change material flows into the heating surface from the narrow path. In order to increase the amount of the heat transmission, Diethylether is added to the working fluid. Diethylether is selected as a phase change material (PCM) that has the boiling point which exists between the heat source of high temperature and low temperature. The parameters of the experiment are additive amount of PCM, rotational speed of the displacer piston and temperature of heat transfer surface. It is shown that it is possible to make exchange of heat amount increase by adding phase change material. The result of this research shows the optimal condition of the difference in temperature in heat processing, number of revolutions, and addition concentration of PCM.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos.42172140,U2244207,and 42202179)Science Foundation for Distinguished Young Scholars of China University of Petroleum,Beijing (No.2462020QNXZ004)+3 种基金China National Petroleum CorporationChina University of Petroleum (Beijing) Strategic Cooperation Science and Technology Project (No.ZLZX2020-01-06)State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum (No.PRP/open-2217)State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development,the University of Liverpool and China Scholarship Council Awards (No.202009110097)the AAPG Foundation Grants-in-Aid award。
文摘In-situ fluid phase behavior is important in determining hydrocarbon contents and the multiphase flow through shale reservoirs.The gas-to-oil ratio(GOR) has been recognized as a critical indicator of fluid types.However,little is known about the impact of fluid phase variation across the thermal maturity on shale oil/gas production(e.g.,estimated ultimate recovery,EUR).According to the specific gravity ratio of oil/gas,the producing GOR was converted and normalized into a mass fraction of gas in total hydrocarbons(MGOR) to compare North American shale oil/gas plays with Chinese shale oil and hybrid gas-condensate plays.A correlation between MGOR,the fluid phases,and production data was established to identify five phase stages of flow.MGORvaries systematically with the different production zones,which shows promise in rapidly indicating the well production performance and high production stages of shale oil/gas plays.The hybrid shale gas condensate index,Tmax,and total gas contents were integrated to present the fluid types and maturity of shale gas-condensates,which indicates fluid phase and production variation across thermal evolution.The results offer a unique perspective on the shale oil reservoir producibility based on the impact of GOR on fluid phases and EUR from the dominant global oil/gas plays.
基金financial support from the Key Project of the National Natural Science Foundation of China(No.52034010)the China Scholarship Council(201906450038)
文摘This work mainly studies the effect of fluid phase momentum transfer mechanisms on the acidizing results,including the retardation effect of the porous structure and the interaction between the fluid phase,such as viscous dissipation and inertial effect.The results show that the acid fluid momentum transfer is influenced by the complex porous structure and fluid viscous dissipation.Eventually,the Stokes-Darcy equation is recommended to be adopted to describe the fluid phase momentum transfer in the following numerical simulation studies of the carbonate acidizing process.Based on this model,a parametric research is carried out to investigate the impact of acid on rock physical characteristics in the stimulation process.Increasing the acid concentration appears to minimize the quantity of acid consumed for the breakthrough.The acid surface reaction rate has a considerable impact on the pore volume to breakthrough and the optimum acid injection rate.The influence of permeability on the acidizing results basically shows a negative correlation with the injection rate.The difference between the acidizing curves of different permeability gradually becomes insignificant with the decrease in injection rate.The existence of isolated fracture and vug significantly reduces acid consumption for the breakthrough.
文摘Based on the fluid phase equilibrium of the C-O-H system, the compositions of var-ious fluid phases under high temperatures and pressures have been calculated in terms of the available thermodynamic data and new P-V-T data and on the assumption of PT = ΣPi in this paper. The results indicate that in this system there are 5 major fluid phases in different pro-portions at various T and P. CH4 is the dominant phase (about 70% ) under relatively lower T and P. Its proportion obviously decreases with increasing T, P and fo2. The results pro-vide sufficient theoretical grounds for discussing the possibility of CH4 formation and the physical-chemical conditions of its stable occurrence and proportion in the geological environment.
文摘A phase diagram of argon based upon percolation transition loci determined from literature experimental p-V isotherms, and simulation values using a Lennard-Jones model shows three fluid phases. The liquid phase spans all temperatures, from a metastable amorphous ground state at 0K, to ultra-high T. There is a supercritical mesophase bounded by percolation transition loci, and a gas phase. Intersection of two percolation loci in the p-T plane thermodynamically defines a critical line between two coexisting gas and liquid critical states at T = Tc, and the single mesophase for T > Tc. A debate on the absence of a van der Waals critical point in the Gibbs p-T density surface is appended.
文摘BZ26-6 Oilfield is a kind of deep metamorphic rock buried-hill volatile oilfield in Bohai Sea, China. Its early development plan is restricted due to the simultaneous production of oil and gas in large sections of reservoirs, unclear understanding of formation fluid properties and uncertainty of gas-oil interface. Through theoretical research on phase recovery and experimental analysis of crude oil phase characteristics in the original formation, characteristic parameters of the equilibrium condensate gas fluid are restored and calculated. Through the superimposed phase diagram of volatile oil and condensate gas, BZ26-6 Oilfield is determined to be a volatile oil reservoir with a condensate gas cap, with formation pressure and saturation pressure of 36.1 MPa, respectively. Based on the research results of oil-gas phase behavior characteristics, the thermodynamic equations and equation of state are jointly used to solve the problem, and the content change curves of each component at different depths are drawn. Combined with the sensitivity analysis of numerical simulation, the gas-oil interface is determined to be -3726 m above sea level. The fluid phase analysis software, Fluidmodeler, is used to simulate volatile oil degassing and condensate gas separation experiments. In combination with oil and gas production data obtained through the production test, the specific oil recovery index and the specific gas recovery index are determined to be 0.408 m<sup>3</sup>/(MPa·d·m) and 1195 m<sup>3</sup>/(MPa·d·m), respectively. And the reasonable production capacity prediction is conducted on the early development of BZ26-6 Oilfield. The research results can provide a theoretical basis for the efficient development of similar complex oil and gas reservoirs.
文摘The quasi-solid-fluid phase transition of granular materials is closely related to the shear rate and solid concentration in addition to their intrinsic properties. The contact duration and the coordination number are two important temporal-spatial parame-ters to describe the granular interaction in phase transition. In this study, characteristics of the contact duration and the coordination number associated with the transition processes are determined using a 3D discrete element model under different shear rates and concentrations. The resulting macroscopic stress and strain-rate relations are discussed. The temporal and spatial parameters provide a linkage between the macroscopic constitutive law and inter- particle micromechanics.
基金the National Natural Science Foundation of China! (No.19834020).
文摘We have prepared novel coated particles, with a conductor graphite core and a dielectric TiO2 coating, as the dispersed phase of electrorheological fluids. One order of magnitude enhancement in the shear stress is obtained by using such composite particles, when it is compared with that of TiO2 particles. The experimental results show a way to get excellent ER system.
基金Sponsored by National Key Technology Research and Development Program in 11th Five-year Plan of China(2008AF33B01)Fuzhou University Foundation for Development of Science and Technology of China(0020-600588)
文摘By means of the computational fluid dynamics software Fluent 6.3, a mathematical model of three-dimensional three-phase fluid flow field in the molten bath of electric arc furnace （EAF） with side accessorial oxygen lances was developed to study the transient phenomena of oxygen jet impingement on the molten steel and the molten slag. The water modeling experiment was carried out to verify the simulation results. The impingement of the supersonic oxygen jet caused impact dent on the molten steel surface accordingly. The area of impact dent changed almost in linear relationship to flow rate of oxygen jet, which can be expressed by a deduced mathematical equation. And the relationship between the impact force of oxygen iet and the correspondingly formed apparent static pressure on molten bath was obtained, which was in linear relationship and a direct proportion, and can also be expressed by a deduced mathematical equation.
基金Project supported by the National Key Basic Research and Development Program of China(No.G1999-0222-08)
文摘The USM-θ model of Bingham fluid for dense two-phase turbulent flow was developed, which combines the second-order moment model for two-phase turbulence with the particle kinetic theory for the inter-particle collision. In this model, phases interaction and the extra term of Bingham fluid yield stress are taken into account. An algorithm for USM-θ model in dense two-phase flow was proposed, in which the influence of particle volume fraction is accounted for. This model was used to simulate turbulent flow of Bingham fluid single-phase and dense liquid-particle two-phase in pipe. It is shown USM-θ model has better prediction result than the five-equation model, in which the particle-particle collision is modeled by the particle kinetic theory, while the turbulence of both phase is simulated by the two-equation turbulence model. The USM-θ model was then used to simulate the dense two-phase turbulent up flow of Bingham fluid with particles. With the increasing of the yield stress, the velocities of Bingham and particle decrease near the pipe centre. Comparing the two-phase flow of Bingham-particle with that of liquid-particle, it is found the source term of yield stress has significant effect on flow.
文摘RH vacuum degasser is a very important secondary refining device in the production of high quality steels. The flow field of molten steel in RH system plays a significant role in determining productivity of the equipment. The homogeneous model and VOF method were often used to predict the flow field in RH system, but these kinds of models simplified the interaction between gas bubbles and molten steel. In the present work, a numerical model of a whole RH system, including vacuum degasser, immersed legs and ladle,was built based on gas-liquid two-fluid model, and it could be used to analyze the interaction between argon bubbles and molten steel, to understand the effect of the bubble size to the flow field.
文摘A packed column supercritical fluid chromatography (SFC) method for the separation of clopidogrel enantiomers on a chiral stationary phase and CO2 with modifier as mobile phase has been developed at an analytical scale. Among 11 different 2 stationary phases the Chiral cel OD-H column showed by far the best separation properties. The influence of different modifiers, injection solvents, temperature, and pressure, and density of the fluid, respectively, on the separation behaviour has been studied. It was found that the separation behaviour strongly depends on the type of modifier and the modifier content. Temperature and pressure are of less influence.
文摘A flow apparatus was set up for measuring the solubility of a solid solute in a supercritical fluid withthe presence of a small amount of entrainer.The solubilities of biphenyl,diphenylamine and benzoic acid insupercritical carbon dioxide with one of the selected entrainers which were ethanol,acetone and n-hexanerespectively,were obtained in the pressure range of 10—32 MPa and the temperature range of 308—318K.Asolvolytic association theory has been proposed to explain the mechanism of entrainer effect,and theexperimental results were reasonably analysed.According to the solvolytic association theory,the association equa-tion of state was adopted to correlate the experimental data with good accuracy.
文摘A mathematical model of two-phase fluid nonlinear flow in the direction of normal of ellipse through low-permeability porous media was established according to a nonlinear flow law expressed in a continuous function with three parameters, a mass conservation law and a concept of turbulent ellipses. A solution to the model was obtained by using a finite difference method and an extrapolation method. Formulas of calculating development index not only before but also after water breaks through an oil well in the condition of two-phase fluid nonlinear flow in the media were derived. An example was discussed. Water saturation distribution was presented. The moving law of drainage front was found. Laws of change of pressure difference with time were recognized. Results show that there is much difference of water saturation distribution between nonlinear flow and linear flow; that drainage front by water moves faster, water breaks through sooner and the index gets worse because of the nonlinear flow; and that dimensionless pressure difference gets larger at the same dimensionless time and difficulty of oil development becomes bigger by the nonlinear flow. Thus, it is necessary that influence of nonlinear flow on development indexes of the oil fields be taken into account. The results provide water-flooding development of the oilfields with scientific basis.
文摘The dynamics of phase separation in two-dimensional binary fluid with low-middle densities was investigated by molecular dynamics simulation. The spinodal decomposition region for symmetric systems may be divided into the diffusive and kinematic region. At an elevated temperature, the motion of particles is diffusive. At a middle temperature, the kinematic mechanism takes effect on the systems with middle density, and the diffusive mechanism holds only for the dilute system. At a low temperature, the phase separation obeys the kinematic mechanism in a wide range of density. For asymmetric systems, the growth of particles A (majority) is different from that of particles B (minority). The diffusive and kinematic regions for the majority are similar to those of symmetric system. The growth exponent for the minority is related to its absolute density and temperature because of its small density.
基金Supported by the National Natural Science Foundation of China(10672022)
文摘Linearized equations of fluid dynamics of cell two phase flow for one dimensional case are proposed. Based on the equations, an analytic solution is derived, in which the frequency of wave is observed. The frequency formula consists of all important parameters of the fluid dynamics. In our observation, the group velocity and phase velocity of the motion of wave propagation are explicitly exhibited as well.
基金Project supported by the National Natural Science Foundation of China （Grant No 10302018）, the Research Grants Council of the Government of the HKSAR, China （Grant No PolyU5172/020）, and the Natural Science Foundation of Zhejiang Province, China （Grant No M103082）.
文摘Based on a lattice Boltzmann method and general principles of porous flow, a numerical technique is presented for analysing the separation of multi-phase immiscible fluids in porous media. The total body force acting on fluid particles is modified by axiding relative permeability in Nithiarasu＇s expression with an axiditional surface tension term. As a test of this model, we simulate the phase separation for the case of two immiscible fluids. The numerical results show that the two coupling relative permeability coefficients K12 and K21 have the same magnitude, so the linear flux-forcing relationships satisfy Onsager reciprocity. Phase separation phenomenon is shown with the time evolution of density distribution and bears a strong similarity to the results obtained from other numerical models and the flows in sands. At the same time, the dynamical rules in this model are local, therefore it can be run on massively parallel computers with well computational efficiency.
文摘Climate change is a reality. The burning of fossil fuels from oil, natural gas and coal is responsible for much of the pollution and the increase in the planet’s average temperature, which has raised discussions on the subject, given the emergencies related to climate. An energy transition to clean and renewable sources is necessary and urgent, but it will not be quick. In this sense, increasing the efficiency of oil extraction from existing sources is crucial, to avoid waste and the drilling of new wells. The purpose of this work was to add diffusive and dispersive terms to the Buckley-Leverett equation in order to incorporate extra phenomena in the temporal evolution between the water-oil and oil-water transitions in the pipeline. For this, the modified Buckley-Leverett equation was discretized via essentially weighted non-oscillatory schemes, coupled with a three-stage Runge-Kutta and a fourth-order centered finite difference methods. Then, computational simulations were performed and the results showed that new features emerge in the transitions, when compared to classical simulations. For instance, the dispersive term inhibits the diffusive term, adding oscillations, which indicates that the absorption of the fluid by the porous medium occurs in a non-homogeneous manner. Therefore, based on research such as this, decisions can be made regarding the replacement of the porous medium or the insertion of new components to delay the replacement.
基金supported by the Science and Technology Support Program of Hebei Province(Cervical spinal canal cerebrospinal fluid movement using 3.0TMR fast phase-contrast cine imaging),No.112061179D
文摘A total of 50 healthy volunteers aged between 18 and 54 years underwent phase-contrast cine MR to assess cerebrospinal fluid flow characteristics in different regions of the vertebral canal. The results revealed that the cerebrospinal fluid peak flow velocity and peak flow rate in the systolic phase were significantly greater than those in the diastolic phase at the same level in the subarachnoid space of the cervical spinal canal. The ventral peak flow velocity and peak flow rate were significantly greater than the post-lateral peak flow velocity and flow rate, while there were no differences between left and right post-lateral subarachnoid peak velocity and flow rate. Moreover, there were no significant differences in peak flow velocity and peak flow rate between the systolic and diastolic phases, ventral, right post-lateral or left post-lateral peak flow velocity and peak flow rate at the same level in the subarachnoid space of the cervical spinal canal among different age groups （18 24, 25 34, 35-44, ≥45 years）.
基金Project(20490224) supported by the National Natural Science Foundation of ChinaProject(2003CB615604) supported by the Major State Basic Research and Development Program of ChinaProject supported by Shengli oil field,SINOPEC Petrochemical Co. Ltd.
文摘Modern processing technology is calling the scientific understanding of dynamic processes,where the science of complex fluids plays a central role.We summarize our recent efforts using the generic approaches of multi-scale physics of complex fluids on apparently irrelevant processes,i.e.the mixing of polymer blends,the processing of thermoplastic(TP) toughened thermosetting(TS) composites using phase separation of TP in TS,as well as the enhanced oil recovery using polymer soft gel.It is emphasized that the thorough physical understanding in multi-scales of time and space through the joint efforts of experiment and theory in each scale is the key issue for the modeling of various processes.
文摘Use of the low temperature (less than 100°C) energy contributes to effective use of heat resources. The cost recovery by power generation is difficult by using an existing system (the binary cycle or the thermoelectric conversion element), because the initial investment is large. The final purpose of this research is development of the low temperature difference drive engine supposing use in a hot-springs resort as a power source for electric power generation. In order that a traveler may look at and delight a motion of an engine, it is made to drive at low-speed number of rotations. An engine cycle of this study is aimed at the development of Stirling cycle engine which can maintain high efficiency in small size. This kind of engine has simple structure;it brings low cost, and it is easy to perform maintenance. However, it is difficult to obtain enough output by this type of engine, because of its low temperature difference. This paper deals with the heat transfer characteristic that the working fluid including a phase change material flows into the heating surface from the narrow path. In order to increase the amount of the heat transmission, Diethylether is added to the working fluid. Diethylether is selected as a phase change material (PCM) that has the boiling point which exists between the heat source of high temperature and low temperature. The parameters of the experiment are additive amount of PCM, rotational speed of the displacer piston and temperature of heat transfer surface. It is shown that it is possible to make exchange of heat amount increase by adding phase change material. The result of this research shows the optimal condition of the difference in temperature in heat processing, number of revolutions, and addition concentration of PCM.
