Predictions of the Joule-Thomson coefficients and inversion curves from the CPA equation of state

Abstract

Several approaches involving some particular cubic equation of state (EoS) have been tested over the last 50 years as attempts to assess the Joule-Thomson coefficient (JTC) and inversion curves, though most of the cubic EoS are limited with regard to delivering good results for associating substances. The present work applies the Cubic Plus Association (CPA) EoS to predict the JTC for several pure substances (methane, ethane, propane, ethylene, benzene, toluene, nitrogen, carbon dioxide, sulfur hexafluoride, water, hydrogen sulfide and ethanol) and mixtures, focusing on systems with at least one associating substance. The results were compared with experimental and correlated data from the literature, as well as with the SRK EoS and molecular simulation. CPA EoS was capable of predicting the general trend for the Joule-Thomson coefficient and inversion curves even at extreme conditions, with reduced pressure values up to 20 and reduced temperatures up to 5.