Estimation of Hansen Solubility Parameters with an Entropy-Based Solubility-Parameter-Translated SRK Equation of State

The equation of state (EoS) is very helpful for the prediction of both high-pressure phase diagrams and fundamental properties. However, the general cubic EoS has low prediction accuracy for compressed and saturated liquid densities and the pure component critical density, especially for highly polar substances like water and alcohol. Therefore, an entropy-based solubility-parameter-translated Soave–Redlich–Kwong equation of state (eSPT-SRK EoS) was developed that incorporates two correction parameters that can be linearly correlated with the critical compressibility factor. The correlated values gave an average relative deviation (ARD) value of 7.9% at the critical density for a database of 28 widely used chemical compounds. Estimation of liquid densities at standard temperature and pressure conditions (298.2 K and 101.3 kPa) gave an average ARD value of 6.1% compared with the original SRK EoS value of 16.6%. The eSPT-SRK EoS was applied to calculate thermodynamic properties (entropy, fugacity, cohesive energy density) and was found to be reliable for estimating entropy-based Hansen-type solubility parameters (eHSPs). The eSPT-SRK EoS was compared with a corrected form of the entropy-based solubility-parameter-translated Peng–Robinson EoS (eSPT-PR EoS), and both functional forms were found to give reliable eHSP values. Therefore, the formulation methodology can be applied to other cubic equations of state for specialized fluid mixtures.