The physical model is described by a seepage coupled system for simulating numerically three-dimensional chemical oil recovery, whose mathematical description includes three equations to interpret main concepts. The p...The physical model is described by a seepage coupled system for simulating numerically three-dimensional chemical oil recovery, whose mathematical description includes three equations to interpret main concepts. The pressure equation is a nonlinear parabolic equation, the concentration is defined by a convection-diffusion equation and the saturations of different components are stated by nonlinear convection-diffusion equations. The transport pressure appears in the concentration equation and saturation equations in the form of Darcy velocity, and controls their processes. The flow equation is solved by the conservative mixed volume element and the accuracy is improved one order for approximating Darcy velocity. The method of characteristic mixed volume element is applied to solve the concentration, where the diffusion is discretized by a mixed volume element method and the convection is treated by the method of characteristics. The characteristics can confirm strong computational stability at sharp fronts and it can avoid numerical dispersion and nonphysical oscillation. The scheme can adopt a large step while its numerical results have small time-truncation error and high order of accuracy. The mixed volume element method has the law of conservation on every element for the diffusion and it can obtain numerical solutions of the concentration and adjoint vectors. It is most important in numerical simulation to ensure the physical conservative nature. The saturation different components are obtained by the method of characteristic fractional step difference. The computational work is shortened greatly by decomposing a three-dimensional problem into three successive one-dimensional problems and it is completed easily by using the algorithm of speedup. Using the theory and technique of a priori estimates of differential equations, we derive an optimal second order estimates in 12 norm. Numerical examples are given to show the effectiveness and practicability and the method is testified as a powerful tool to solve the important problems.展开更多
The efficient separation of acetylene(C_(2)H_(2))from carbon dioxide(CO_(2))and CnH_(4)(n=1 and 2)to manufacture high purity C_(2)H_(2)and recover other light hydrocarbons is technologically important,while posing sig...The efficient separation of acetylene(C_(2)H_(2))from carbon dioxide(CO_(2))and CnH_(4)(n=1 and 2)to manufacture high purity C_(2)H_(2)and recover other light hydrocarbons is technologically important,while posing significant challenges.Herein,we reported a new TiF62−anion(TIFSIX)pillared metal-organic framework(MOF)ZNU-5(ZNU=Zhejiang Normal University)with ultramicropores for highly selective C_(2)H_(2)capture with low adsorption heat through gate opening based molecular sieving effect.ZNU-5 takes up a large amount of C_(2)H_(2)(128.6 cm^(3)/g)at 1.0 bar and 298 K but excludes CO_(2),CH_(4),and C_(2)H_(4).Such high capacity has never been realized in MOFs with molecular sieving.The breakthrough experiments further confirmed the highly selective C_(2)H_(2)separation performance from multi-component gas mixtures.3.3,2.8,and 2.2 mmol/g of C_(2)H_(2)is captured at ZNU-5 from equimolar C_(2)H_(2)/CO_(2),C_(2)H_(2)/CO_(2)/CH_(4),and C_(2)H_(2)/CO_(2)/CH_(4)/C_(2)H_(4)mixtures,respectively.Furthermore,2.6,2.0,and 1.5 mmol/g of>98%purity C_(2)H_(2)can be recycled from the desorption process.Combining high working capacity,low adsorption heat,as well as good recyclability,ZNU-5 is promising for C_(2)H_(2)purification.展开更多
基金Supported by the National Natural Science Foundation of China(11101124 and 11271231)Natural Science Foundation of Shandong Province(ZR2016AM08)National Tackling Key Problems Program(2011ZX05052,2011ZX05011-004)
文摘The physical model is described by a seepage coupled system for simulating numerically three-dimensional chemical oil recovery, whose mathematical description includes three equations to interpret main concepts. The pressure equation is a nonlinear parabolic equation, the concentration is defined by a convection-diffusion equation and the saturations of different components are stated by nonlinear convection-diffusion equations. The transport pressure appears in the concentration equation and saturation equations in the form of Darcy velocity, and controls their processes. The flow equation is solved by the conservative mixed volume element and the accuracy is improved one order for approximating Darcy velocity. The method of characteristic mixed volume element is applied to solve the concentration, where the diffusion is discretized by a mixed volume element method and the convection is treated by the method of characteristics. The characteristics can confirm strong computational stability at sharp fronts and it can avoid numerical dispersion and nonphysical oscillation. The scheme can adopt a large step while its numerical results have small time-truncation error and high order of accuracy. The mixed volume element method has the law of conservation on every element for the diffusion and it can obtain numerical solutions of the concentration and adjoint vectors. It is most important in numerical simulation to ensure the physical conservative nature. The saturation different components are obtained by the method of characteristic fractional step difference. The computational work is shortened greatly by decomposing a three-dimensional problem into three successive one-dimensional problems and it is completed easily by using the algorithm of speedup. Using the theory and technique of a priori estimates of differential equations, we derive an optimal second order estimates in 12 norm. Numerical examples are given to show the effectiveness and practicability and the method is testified as a powerful tool to solve the important problems.
基金support by the National Natural Science Foundation of China(No.21908193)Jinhua Industrial Key Project(No.2021A22648)+2 种基金S.D.acknowledged the financial support by the National Natural Science Foundation of China(No.21871231)the Special Funds for Basic Scientific Research of Zhejiang University(Nos.2019QNA3010 and K20210335)support by the National Natural Science Foundation of China(No.22205207).
文摘The efficient separation of acetylene(C_(2)H_(2))from carbon dioxide(CO_(2))and CnH_(4)(n=1 and 2)to manufacture high purity C_(2)H_(2)and recover other light hydrocarbons is technologically important,while posing significant challenges.Herein,we reported a new TiF62−anion(TIFSIX)pillared metal-organic framework(MOF)ZNU-5(ZNU=Zhejiang Normal University)with ultramicropores for highly selective C_(2)H_(2)capture with low adsorption heat through gate opening based molecular sieving effect.ZNU-5 takes up a large amount of C_(2)H_(2)(128.6 cm^(3)/g)at 1.0 bar and 298 K but excludes CO_(2),CH_(4),and C_(2)H_(4).Such high capacity has never been realized in MOFs with molecular sieving.The breakthrough experiments further confirmed the highly selective C_(2)H_(2)separation performance from multi-component gas mixtures.3.3,2.8,and 2.2 mmol/g of C_(2)H_(2)is captured at ZNU-5 from equimolar C_(2)H_(2)/CO_(2),C_(2)H_(2)/CO_(2)/CH_(4),and C_(2)H_(2)/CO_(2)/CH_(4)/C_(2)H_(4)mixtures,respectively.Furthermore,2.6,2.0,and 1.5 mmol/g of>98%purity C_(2)H_(2)can be recycled from the desorption process.Combining high working capacity,low adsorption heat,as well as good recyclability,ZNU-5 is promising for C_(2)H_(2)purification.
