Abstract A six parameter Quartic equation of state (QEOS) is presented in this work to explore the scope of a non-cubic equation of state for the prediction of thermodynamic properties and analyze its improvement over the commonly used cubic equations of state. The QEOS uses 4 compound specific parameters in addition to the critical constants. The QEOS predicted results for various thermodynamic properties are compared with experimental data and with results obtained from Ghoderao-Dalvi-Narayan (4PGDN1) equation of state. The QEOS fits data best when it most resembles a Cubic EOS (CEOS) obtained by setting one compound specific parameter e to nearly zero. This presents an opportunity to use the CEOS for practical calculations while using the theoretically more correct QEOS for theoretical analysis.

中文翻译：

---

伪装成四次方的状态三次方程

摘要 本文提出了一个六参数四次状态方程（QEOS），以探索非三次状态方程用于预测热力学性质的范围，并分析其对常用三次状态方程的改进。除了关键常数之外，QEOS 还使用 4 个化合物特定参数。将 QEOS 对各种热力学性质的预测结果与实验数据以及从 Ghoderao-Dalvi-Narayan (4PGDN1) 状态方程获得的结果进行比较。当 QEOS 最类似于通过将一个复合特定参数 e 设置为接近零而获得的三次 EOS (CEOS) 时，QEOS 最适合数据。这提供了使用 CEOS 进行实际计算的机会，同时使用理论上更正确的 QEOS 进行理论分析。