A New Semi-Empirical Model for Saturated Vapor Density of Pure Compounds

Alexander Kud , Christophe Coquelet (1) , Stefan Maixner

1 CTP - Centre Thermodynamique des Procédés

Many empirical models exist to describe the saturated vapor density. The majority of these models are detached from a physics basis, which often makes it difficult to select the most appropriate model for further thermodynamic modeling. Such empirical models are still used today because many equations of state that do not describe vapor density well enough. The model presented here is based on a physical and a heuristic equation. It offers many advantages because it includes both the vapor pressure and the compressibility factor information for the saturated vapor line. In this manner, it is possible to describe the vapor density with one equation and only three parameters. The new model is independent of the compounds structure because it is based on vapor density measurements. It was tested in comparison to six frequently used models in terms of accuracy and thermodynamic consistency. The new model received the best rating and provides useful tool for thermodynamic modeling and process design. The assessment of the models was based on Monte Carlo simulations and strict statistical methods for validating models. The new model can also be used in a cubic equation of state for the vapor pressure and vapor density correction.

Domaines: Génie des procédés; Génie chimique; Chimie théorique et/ou physique

Alexander Kud, Christophe Coquelet, Stefan Maixner. A New Semi-Empirical Model for Saturated Vapor Density of Pure Compounds. Journal of Chemical and Engineering Data, 2020, 65 (2), pp.577-590. ⟨10.1021/acs.jced.9b00787⟩. ⟨hal-02493875⟩