scholarly journals Thermal Diffusion and Molecular Diffusion Values for Some Alkane Mixtures: A Comparison between Thermogravitational Column and Thermal Diffusion Forced Rayleigh Scattering

2008 ◽  
Vol 112 (28) ◽  
pp. 8340-8345 ◽  
Author(s):  
Pablo Blanco ◽  
Pavel Polyakov ◽  
M. Mounir Bou-Ali ◽  
Simone Wiegand
Keyword(s):  
Thermal Diffusion ◽  
Rayleigh Scattering ◽  
Molecular Diffusion ◽  
Thermogravitational Column

scholarly journals Thermal Diffusion Forced Rayleigh Scattering Setup Optimized for Aqueous Mixtures

2007 ◽  
Vol 111 (51) ◽  
pp. 14169-14174 ◽  
Author(s):  
Simone Wiegand ◽  
Hui Ning ◽  
Hartmut Kriegs
Keyword(s):  
Thermal Diffusion ◽  
Rayleigh Scattering ◽  
Aqueous Mixtures

Two-Phase Multicomponent Diffusion and Convection for Reservoir Initialization

2006 ◽  
Vol 9 (05) ◽  
pp. 530-542 ◽  
Author(s):  
Hadi Nasrabadi ◽  
Kassem Ghorayeb ◽  
Abbas Firoozabadi
Keyword(s):  
Thermal Conductivity ◽  
Porous Medium ◽  
Natural Convection ◽  
Temperature Gradient ◽  
Thermal Diffusion ◽  
Multicomponent Diffusion ◽  
Compositional Variation ◽  
Horizontal Temperature Gradient ◽  
Two Phase ◽  
Thermogravitational Column

Summary We present formulation and numerical solution of two-phase multicomponent diffusion and natural convection in porous media. Thermal diffusion, pressure diffusion, and molecular diffusion are included in the diffusion expression from thermodynamics of irreversible processes. The formulation and the numerical solution are used to perform initialization in a 2D cross section. We use both homogeneous and layered media without and with anisotropy in our calculations. Numerical examples for a binary mixture of C1/C3 and a multicomponent reservoir fluid are presented. Results show a strong effect of natural convection in species distribution. Results also show that there are at least two main rotating cells at steady state: one in the gas cap, and one in the oil column. Introduction Proper initialization is an important aspect of reliable reservoir simulations. The use of the Gibbs segregation condition generally cannot provide reliable initialization in hydrocarbon reservoirs. This is caused, in part, by the effect of thermal diffusion (caused by the geothermal temperature gradient), which cannot be neglected in some cases; thermal diffusion might be the main phenomenon affecting compositional variation in hydrocarbon reservoirs, especially for near-critical gas/condensate reservoirs (Ghorayeb et al. 2003). Generally, temperature increases with increasing burial depth because heat flows from the Earth's interior toward the surface. The temperature profile, or geothermal gradient, is related to the thermal conductivity of a body of rock and the heat flux. Thermal conductivity is not necessarily uniform because it depends on the mineralogical composition of the rock, the porosity, and the presence of water or gas. Therefore, differences in thermal conductivity between adjacent lithologies can result in a horizontal temperature gradient. Horizontal temperature gradients in some offshore fields can be observed because of a constant water temperature (approximately 4°C) in different depths in the seabed floor. The horizontal temperature gradient causes natural convection that might have a significant effect on species distribution (Firoozabadi 1999). The combined effects of diffusion (pressure, thermal, and molecular) and natural convection on compositional variation in multicomponent mixtures in porous media have been investigated for single-phase systems (Riley and Firoozabadi 1998; Ghorayeb and Firoozabadi 2000a).The results from these references show the importance of natural convection, which, in some cases, overrides diffusion and results in a uniform composition. Natural convection also can result in increased horizontal compositional variation, an effect similar to that in a thermogravitational column (Ghorayeb and Firoozabadi 2001; Nasrabadi et al. 2006). The combined effect of convection and diffusion on species separation has been the subject of many experimental studies. Separation in a thermogravitational column with both effects has been measured widely (Schott 1973; Costeseque 1982; El Mataaoui 1986). The thermogravitational column consists of two isothermal vertical plates with different temperatures separated by a narrow space. The space can be either without a porous medium or filled with a porous medium. The thermal diffusion, in a binary mixture, causes one component to segregate to the hot plate and the other to the cold plate. Because of the density gradient caused by temperature and concentration gradients, convection flow occurs and creates a concentration difference between the top and bottom of the column. Analytical and numerical models have been presented to analyze the experimental results (Lorenz and Emery 1959; Jamet et al. 1992; Nasrabadi et al. 2006). The experimental and theoretical studies show that the composition difference between the top and bottom of the column increases with permeability until an optimum permeability is reached. Then, the composition difference declines as permeability increases. The process in a thermogravitational column shows the significance of the convection from a horizontal temperature gradient.

Soret Effect for a Ternary Mixture in Porous Cavity: Modeling With Variable Diffusion Coefficients and Viscosity

2008 ◽  
Vol 130 (8) ◽  
Author(s):  
T. J. Jaber ◽  
Y. Yan ◽  
M. Z. Saghir
Keyword(s):  
Thermal Diffusion ◽  
Diffusion Coefficients ◽  
Molecular Diffusion ◽  
Soret Effect ◽  
Left Wall ◽  
Porous Cavity ◽  
Buoyancy Convection ◽  
Variable Diffusion ◽  
Variable Diffusion Coefficients ◽  
The Right

A porous cavity filled with methane (C1), n-butane (nC4), and dodecane (C12) at a pressure of 35.0MPa is used to investigate numerically the flow interaction due to the presence of thermodiffusion and buoyancy forces. A lateral heating condition is applied with the left wall maintained at 10°C and the right wall at 50°C. The molecular diffusion and thermal diffusion coefficients are functions of temperature, concentration, and viscosity of mixture components. It has been found that for permeability below 200md the thermodiffusion is dominant; and above this level, buoyancy convection becomes the dominant mechanism. The variation of viscosity plays an important role on the molecular and thermal diffusion.

Polymer Polydispersity Analysis by Thermal Diffusion Forced Rayleigh Scattering

1996 ◽  
Vol 29 (9) ◽  
pp. 3203-3211 ◽  
Author(s):  
P. Rossmanith ◽  
W. Köhler
Keyword(s):  
Thermal Diffusion ◽  
Rayleigh Scattering

Molecular and Thermal Diffusion Coefficients Of n-Dodecane, Isobutylbenzene and Tetrahydronaphtalene Hydrocarbon Mixtures in Porous Media

2021 ◽  
Author(s):  
Mustafa Khawaja
Keyword(s):  
Experimental Data ◽  
Porous Media ◽  
Binary Mixtures ◽  
Thermal Diffusion ◽  
Diffusion Coefficients ◽  
Molecular Diffusion ◽  
Hydrocarbon Mixture ◽  
Permeability Model ◽  
Diffusion And Convection ◽  
Experimental Values

The thermal diffusion phenomenon was studied in detail by utilizing mixtures consisting of normal alkenes and two aromatics (n-Dodecane, Isobutylbenzene and 1,2,3,4-Tetrahydronaphtalene) based on comparison with available experimental data. This study presents the first report of a comparison of thermal diffusion coefficients of a ternary hydrocarbon mixture with experimental data in the literature. In addition to thermal diffusion coefficients, molecular diffusion coefficients are also measured and compared with Benchmark experimental values for three binary mixtures. Furthermore, molecular and thermal diffusion coefficients for three binary mixtures are used to correlate and estimate the thermal diffusion coefficients in the ternary hydrocarbon mixture. The thermo-solutal convection in porous media was simulated numerically using the Firoozabadi model in order to investigate the composition variation due to the processes of thermal diffusion and convection. Finally, a multi-porosity/multi-permeability model was utilized to further analyze the processes of thermal diffusion and convection in fractured porous media.

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