Testing the ability of various equations of state to reproduce high-pressure isotherm crossings in the (伪, P) plane
- 作者：Romain Privat ; romain.privat@univ-lorraine.fr ; Franç ; ois Gaillochet ; Jean-Noë ; l Jaubert
- 关键词：Isotherm crossing ; Isotherm intersection ; Isobaric expansivity ; Repulsive forces ; Carnahan&ndash ; Starling ; PC-SAFT ; Cubic equations ; Peng&ndash ; Robinson ; Soave&ndash ; Redlich&ndash ; Kwong ; Van der Waals
- 刊名：Fluid Phase Equilibria
- 出版年：2012
- 期刊代码：32_03783812
- 类别：ce
- 出版时间：15 August, 2012
- 卷：327
- 期：Complete
- 页码：45-57
- 文件大小：2458 K
摘要
This paper focuses on a singularity exhibited by most dense fluids in the (伪, P) plane (where 伪 denotes the isobaric expansivity and P, the pressure): for a given fluid, nearly all isothermal curves share a common intersection point. In this paper, we test the capacity of a series of equations of state to model this little-known phenomenon. Equations of state that can be written as the sum of an attractive and a repulsive term are first considered. As a result, equations of state involving a Carnahan-Starling repulsive term always predict the aforementioned crossing point contrary to equations of state involving a classical Van der Waals repulsive term. Quantitatively, the Carnahan-Starling-Van der Waals (CS-VdW) equation of state and the Carnahan-Starling-Soave-Redlich-Kwong (CS-SRK) equation of state both lead to satisfactory results. In addition, some pitfalls of the Carnahan-Starling-Peng-Robinson (CS-PR) equation of state are identified which justifies that this model cannot represent dense-fluid behaviors. The Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equation of state is then tested. The obtained results are more extremely satisfactory when compared to the CS-vdW equation of state. Finally, a general criterion that must be verified by equations of state in order to predict isotherm crossings is proposed and illustrated.