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.