Abstract In the framework of the proposed theoretical model crossover and scaling equations of state for near-critical multicomponent hydrocarbon mixture were obtained. To elaborate the equations of state the experimental data measured on the serial setup intended for comprehensive pressure-volume-temperature (PVT) research of a natural gas-condensate systems were used. The information concerning the mixture composition was not involved. The obtained equations describe the experimental data with the accuracy not exceeding the measurement inaccuracy. It has been shown that in extended range of thermodynamic parameters the crossover equation of state looks more reliable. The crossover model describes the transition from the scaling behavior to the mean-field behavior, which is typical for cubic and multiparameter equations of state. The model was extended for calculation of the volume fractions of gas and liquid phases needed for practical applications. In addition, the expression for isothermal compressibility has been derived. It was demonstrated that the isothermal compressibility has a cusp-like anomaly in the close vicinity of the critical point.

中文翻译：

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临界点附近模型烃类三元混合物的热力学性质：使用交叉状态方程的测量和建模

摘要 在提出的理论模型框架内，得到了近临界多组分烃混合物的交叉和标度状态方程。为了详细说明状态方程，使用了在用于天然气凝析油系统综合压力-体积-温度 (PVT) 研究的串行装置上测量的实验数据。不涉及有关混合物成分的信息。得到的方程描述了实验数据，精度不超过测量误差。已经表明，在扩展的热力学参数范围内，交叉状态方程看起来更可靠。交叉模型描述了从缩放行为到平均场行为的转变，这对于三次和多参数状态方程来说是典型的。该模型被扩展用于计算实际应用所需的气相和液相的体积分数。此外，还导出了等温压缩性的表达式。结果表明，等温压缩性在临界点附近具有尖峰状异常。