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.

中文翻译：

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高压高温下二元CO ₂ +正癸烷和三元CO ₂ +正癸烷+萘的密度和体积行为

通过使用振动管密度计，分别测量了二氧化碳+正癸烷二元体系和二氧化碳+正癸烷+萘三元体系的密度。在318.15至358.15 K的温度下，测量涵盖第一个系统的CO ₂摩尔组成分别为0.1182、0.3050、0.6271和0.9539。对于三元混合物，对四种组成进行了测量：高烷烃，高芳烃，高CO ₂和一个等摩尔含量，在328.15–423.15 K的温度范围内。根据这些数据，计算出两个系统的过量摩尔体积，这些二元混合物在较低温度和较高压力下均显示正值，而对于二元混合物则显示负值。在整个组成范围内的三元混合物。对于这两个系统，通过使用修正的Tammann-Tait方程将密度与温度和压力的函数相关联，二元和三元系统的最大偏差分别为0.63％和1.72％。另外，从实验密度数据计算出等温压缩性和等压热膨胀率。观察到在较低压力和较高CO ₂下发现较高的可压缩性值二元和三元系统的内容。与浓CO ₂系统相比，浓芳系统的可压缩性较低。关于等压热膨胀系数，所有二元混合物的温度依赖性都可以忽略。但是，对于三元混合物，这种依赖性与混合物组成密切相关。