Abstract

A methodology to predict solid-liquid, solid-vapor, and liquid-vapor phase coexistences using a non-cubic equation of state is presented. The solid phase is additional to the liquid and vapor phases that can be worked with a cubic equation of state; thus, the triple point of the substance is represented. For a given substance, the seven parameters of this equation of state are obtained using the following data: the liquid-vapor critical point, acentric factor, boiling point temperature, and triple point temperature. The procedure to do this is described and is used to validate the methodology through obtaining the pure component parameters of this equation of state for 40 pure alkanes. As examples of the capacity of the reported non-cubic EoS to represent the coordinates of the three different phase transitions, predicted P-T and P-V phase transition diagrams are reported for methane, pentane and octane, and they are in good agreement with experimental data. This methodology is suitable to be used with any substance for which the density of solid phase is higher than that of liquid phase.

摘要

提出了一种使用非三次状态方程来预测固-液、固-汽和液-汽相共存的方法。固相是液相和气相的补充，可以用三次状态方程处理；因此，表示物质的三相点。对于给定的物质，该状态方程的七个参数是使用以下数据获得的：液-气临界点、离心因子、沸点温度和三相点温度。描述了执行此操作的过程，并用于通过获得 40 种纯烷烃的该状态方程的纯组分参数来验证该方法。作为报告的非立方 EoS 表示三个不同相变坐标的能力的例子，报告了甲烷、戊烷和辛烷的预测 PT 和 PV 相变图，它们与实验数据非常吻合。该方法适用于固相密度高于液相密度的任何物质。