Instability theory is applied to diffusion-convection phenomenon in porous media, where the area in direction of transfer is large and viscosity of the oil varies due to gas dissolution. An important application of th...Instability theory is applied to diffusion-convection phenomenon in porous media, where the area in direction of transfer is large and viscosity of the oil varies due to gas dissolution. An important application of this theory arises where diffusion-convection is employed as an EOR technique in oil reservoirs. As a bed of gas is formed below a colunm of oil, gas starts to diffuse into the oil. Therefore, the oil becomes lighter and an inverse gradient of density is developed as more gas diffuses in. Although this inverse density gradient is potentially unstable, convection will not initiate until the gradient extends to a certain value. The condition at which convection begins is known as "the onset of convectin" and is well specified by the dimensionless Rayleigh number. In this study, an instability analysis is made for convection-diffusion in large porous media. Unlike Other studies where viscosity is assumed constant in this work viscosity is postulated to be a function of gas concentration. It is shown that the mathematical model developed reduces to previous models if the viscosity vacations are ignored.展开更多
In this work, indium nitride(InN) films were successfully grown on porous silicon(PS) using metal oxide chemical vapor deposition(MOCVD) method. Room temperature photoluminescence(PL) and field emission scanning elect...In this work, indium nitride(InN) films were successfully grown on porous silicon(PS) using metal oxide chemical vapor deposition(MOCVD) method. Room temperature photoluminescence(PL) and field emission scanning electron microscopy(FESEM) analyses are performed to investigate the optical, structural and morphological properties of the InN/PS nanocomposites. FESEM images show that the pore size of InN/PS nanocomposites is usually less than 4 μm in diameter, and the overall thickness is approximately 40 μm. The InN nanoparticles penetrate uniformly into PS layer and adhere to them very well. Nitrogen(N) and indium(In) can be detected by energy dispersive spectrometer(EDS). An important gradual decrease of the PL intensity for PS occurs with the increase of oxidation time, and the PL intensity of PS is quenched after 24 h oxidization. However, there is a strong PL intensity of InN/PS nanocomposites at 430 nm(2.88 eV), which means that PS substrate can influence the structural and optical properties of the InN, and the grown InN on PS substrate has good optical quality.展开更多
文摘Instability theory is applied to diffusion-convection phenomenon in porous media, where the area in direction of transfer is large and viscosity of the oil varies due to gas dissolution. An important application of this theory arises where diffusion-convection is employed as an EOR technique in oil reservoirs. As a bed of gas is formed below a colunm of oil, gas starts to diffuse into the oil. Therefore, the oil becomes lighter and an inverse gradient of density is developed as more gas diffuses in. Although this inverse density gradient is potentially unstable, convection will not initiate until the gradient extends to a certain value. The condition at which convection begins is known as "the onset of convectin" and is well specified by the dimensionless Rayleigh number. In this study, an instability analysis is made for convection-diffusion in large porous media. Unlike Other studies where viscosity is assumed constant in this work viscosity is postulated to be a function of gas concentration. It is shown that the mathematical model developed reduces to previous models if the viscosity vacations are ignored.
基金supported by the Xinjiang Science and Technology Project(No.2015211C275)
文摘In this work, indium nitride(InN) films were successfully grown on porous silicon(PS) using metal oxide chemical vapor deposition(MOCVD) method. Room temperature photoluminescence(PL) and field emission scanning electron microscopy(FESEM) analyses are performed to investigate the optical, structural and morphological properties of the InN/PS nanocomposites. FESEM images show that the pore size of InN/PS nanocomposites is usually less than 4 μm in diameter, and the overall thickness is approximately 40 μm. The InN nanoparticles penetrate uniformly into PS layer and adhere to them very well. Nitrogen(N) and indium(In) can be detected by energy dispersive spectrometer(EDS). An important gradual decrease of the PL intensity for PS occurs with the increase of oxidation time, and the PL intensity of PS is quenched after 24 h oxidization. However, there is a strong PL intensity of InN/PS nanocomposites at 430 nm(2.88 eV), which means that PS substrate can influence the structural and optical properties of the InN, and the grown InN on PS substrate has good optical quality.
