Abstract An equation of state (EOS) in the form of Helmholtz free energy for fluid mixtures was improved by using four mixing parameters. It can calculate the pressure-volume-temperature-composition (PVTx) and vapor-liquid equilibrium (VLE) properties of the CO2–N2 fluid mixture. This EOS is based on highly accurate EOSs of pure CO2 and N2 fluids and contains a simple generalized departure function of Lemmon and Jacobsen (1999). This EOS can reproduce experimental PVTx and VLE data available up to 673 K and 1000 bar, with an accuracy within or close to experimental uncertainties. The EOS of CO2–N2 fluid mixture and an updated Gibbs free energy model of solid CO2, can be combined to determine the compositions and molar volumes of CO2–N2 fluid inclusions with the melting temperature of solid CO2 and the vapor-liquid homogenization temperature which can be directly obtained from experimental microthermometric analysis. Isochores of CO2–N2 inclusions can be easily calculated from this EOS.

中文翻译：

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CO2-N2二元流体混合物的改进状态方程及其在流体包裹体研究中的应用

摘要 通过使用四个混合参数改进了流体混合物的亥姆霍兹自由能形式的状态方程（EOS）。它可以计算 CO2-N2 流体混合物的压力-体积-温度-成分 (PVTx) 和汽液平衡 (VLE) 特性。该 EOS 基于纯 CO2 和 N2 流体的高精度 EOS，并包含 Lemmon 和 Jacobsen (1999) 的简单广义偏离函数。该 EOS 可以再现高达 673 K 和 1000 bar 的实验 PVTx 和 VLE 数据，精度在或接近实验不确定性。CO2-N2 流体混合物的 EOS 和固体 CO2 的更新吉布斯自由能模型，可以结合固体 CO2 的熔化温度和汽液均质温度来确定 CO2-N2 流体包裹体的组成和摩尔体积，这些温度可以通过实验显微测温分析直接获得。从这个 EOS 可以很容易地计算出 CO2-N2 夹杂物的等值线。