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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