Densities of the carbon dioxide + n-decane binary system and carbon dioxide + n-decane + naphthalene ternary system have been measured up to 130 and 100 MPa, respectively, by using a vibrating tube densitometer. The measurements covered the molar compositions of CO2 of 0.1182, 0.3050, 0.6271, and 0.9539 for the first system, at temperatures from 318.15 to 358.15 K. While for the ternary mixtures, the measurements were performed for four compositions: high alkane, high aromatic, high CO2, and one equimolar content, at a temperature range of 328.15–423.15 K. From these data, excess molar volumes were calculated for both systems, showing positive values at lower temperatures and higher pressures for the binary mixtures, while negative values were observed for the ternary mixtures over the entire composition range. For both systems, the density was correlated by using a modified Tammann–Tait equation, as a function of temperature and pressure, presenting a maximum deviation of 0.63 and 1.72% for the binary and ternary systems, respectively. Additionally, isothermal compressibility and isobaric thermal expansivity were calculated from the experimental density data. It was observed that higher compressibility values were found at lower pressures and at higher CO2 content for both binary and ternary systems. Rich aromatic systems are less compressible when compared to rich CO2 systems. Regarding isobaric thermal expansivity, temperature dependence could be neglected for all binary mixtures. However, for the ternary mixtures, this dependence was strongly related to mixture composition.

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This paper presents density experimental data for pure cis-decalin and trans-decalin, along with carbon dioxide + ndecane + cis-decalin (or + trans-decalin) ternary systems for a temperature from 298.15 to 423.15 K up to 100 MPa by using a vibrating tube densitometer. Ternary mixture compositions have been chosen to cover four different regions as follows: (i) high CO 2 content (x CO2 = 0.60, x n-decane = 0.20, and x decalin = 0.20), (ii) high alkane content (x CO2 = 0.20, x n-decane = 0.60, and x decalin = 0.20), (iii) high aromatic content (x CO2 = 0.20, x n-decane = 0.20, and x decalin = 0.60), and an equimolar content (x CO2 = 0.33, x n-decane = 0.33, and x decalin = 0.33). Excess molar volumes were calculated for both ternary systems, showing negative values over the entire composition range. Additionally, for both systems, experimental density data were correlated to the modified Tammann−Tait equation as a function of temperature and pressure. The adjusted equation presented a maximum deviation (MD) of 1.72%. Moreover, isothermal compressibility and isobaric thermal expansivity were calculated from the experimental density data. It was observed for both ternary systems that above 65 MPa, there is a negligible effect of pressure on isothermal compressibility regardless of the ternary system studied. For isobaric thermal expansivity, temperature dependence was found to be important at pressures below 45 MPa, while above 65 MPa is independent of temperature.

This paper presents density experimental data for pure n-butylcyclohexane, along with carbon dioxide + n-decane + n-butylcyclohexane ternary mixtures, for temperature ranging from 298.15 to 423.15 K and pressure was up to 100.0 MPa. Density measurements were made using a vibrating tube densitometer. Ternary mixture compositions were defined in four different classes, as follows: (i) high CO2 content (x CO2 = 0.60; x n‑decane = 0.20; x n‑butylcyclohexane = 0.20), (ii) high alkane content (x CO2 = 0.20; x n‑decane = 0.60; x n‑butylcyclohexane = 0.20), (iii) high cycloparaffin content (x CO2 = 0.20; x n‑decane = 0.20; x n‑butylcyclohexane = 0.60), and (iv) equimolar content (x CO2 = x n‑decane = x n‑butylcyclohexane = 0.33). From these data sets, excess molar volumes were calculated showing negative values over the entire composition range for all ternary systems. Experimental density data were correlated to the modified Tammann–Tait equation as a function of temperature and pressure. The adjusted equation presented a maximum deviation (MD) of 1.12%. Additionally, isothermal compressibility (k T ) and isobaric thermal expansion coefficient (α p ) were calculated from the experimental density data. It was observed that isothermal compressibility (k T ) increases by increasing temperature and isobaric thermal expansion coefficient (α p ) remains constant for a pressure up to 55.0 MPa for all ternary systems studied here.