In this work, we have measured the densities of binary mixtures of n-dodecane, 1-phenyl-2-methylpropane, and 1,2,3,4-tetrahydronaphthalene for pressures varying from (0.1 to 20) MPa at an average temperature of 25 °C. By a derivative method, we have determined the thermal expansion and concentration expansion coefficients for binary mixtures of equal mass fraction. In addition, viscosities have been measured and compared with theoretical estimates. To accurately predict the thermal expansion and concentration expansion coefficients, the densities of the binary mixtures were calculated using PC-SAFT, Peng-Robinson, and volume translated Peng-Robinson equations of state. The comparison with measured densities showed that PC-SAFT has a better agreement with experimental data than the other equations of state. From calculated densities we evaluated the thermal expansion and concentration expansion variation coefficients. We have found that PC-SAFT gives a suitable prediction for the two derivative properties unlike the two other equations of state. The combination of the model of Lohrenz-Bray-Clark for the viscosity of liquid mixtures and the densities calculated with the three equations of state gave a poor prediction of the viscosities of the binary mixtures. Experimental SectionMaterials. The 1,2,3,4-tetrahydronaphthalene (99 %), ndodecane (99+ %), and 1-phenyl-2-methylpropane (99 %) were † Part of the special section "2008 European Conference on Thermophysical Properties".

An accurate thermodi¤usion model is of paramount importance to the petroleum industry for the prediction of the compositional variation in hydrocarbon reservoirs. As the most recent theoretical development, Kempers and Firoozabadi models can be used for both binary and multicomponent mixtures. In this paper, we verified these models with three ternary hydrocarbon mixtures. The results reveal that the accuracy of the thermal di¤usion coe‰-cients relies on the accuracy of the thermodynamic properties from equations of state, corresponding Fick's di¤usion coe‰cients, and the thermal di¤usion modeling.

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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.

A three-dimensional numerical simulation to study the effect of magnetic field on the fluid flow, heat and mass transfer is investigated. By applying axial and rotating magnetic field (RMF), an attempt was made to suppress the buoyancy convection in the Ge0.98Si0.02 solution zone in order to get homogeneity with flat growth interface. It was found that the intensity of the flow at the centre of the crucible decreased at a faster rate compared to the flow near the walls when increasing axial magnetic field intensity. This behaviour created a stable and uniform silicon distribution in the horizontal plane near the growth interface. Different magnetic field intensities for different rotational speeds (2, 7 and 10 rpm) were examined. The results showed that the RMF has a marked effect on the silicon concentration, changing it from convex to nearly flat when the magnetic field intensity increased.

There has been a discussion that the thermodiffusion in porous medium is not identical to thermodiffusion in clear liquid. To validate this finding, a new thermodiffusion cell has been designed to measure thermal and molecular diffusion coefficients of binary mixture in porous medium under high pressure. A porous layer located between two liquid layers that cross two laser beams, is used. The difference of refractive index is obtained from the analysis of the interferograms recorded with a CCD camera. From the kinetics, the values of molecular and thermal diffusion coefficients through the porous medium were determined. The two binary systems dodecane (C12) and isobutylbenzene (IBB), and dodecane (C12) and tetrahydronaphthalene (THN) are used to validate the experimental setup at atmospheric pressure. Experimental results reveal an excellent agreement with benchmark values and a good agreement with theoretical data.

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