A modified perturbed chain‐statistical associating fluid theory equation of state for water which includes an association dependent hard sphere diameter

Abstract

The concept of an association dependent hard sphere diameter is introduced as a means to obtain an accurate perturbed chain‐statistical associating fluid theory (PC‐SAFT) equation of state model for water. The new approach is demonstrated to be a step change in accuracy for the representation of pure water properties as compared with standard PC‐SAFT applications. Extension of the approach to mixtures is discussed.

Investigation of the Alcohols and Water Hydrogen Bonding Structure via Monomer Fraction Studies

“…It is of interest that the DAPT theory represents some water anomalous properties like the water density maximum. , The DAPT approach developed by Marshall is the only SAFT-inspired model which, to the best of our knowledge, can represent the maximum water density at 1 bar and at the same time shows C p minima and speed of sound maxima at various pressures. Marshall presented many models − in the SAFT framework for water (and other associating fluids). Several concepts are used, e.g., cooperativity, second-order perturbation theory, etc., but none of these other approaches can represent the maximum water density.…”

“…Association equations of state (EoS), belonging to SAFT (statistical associating fluid theory), quasi-chemical, and other concepts, can predict monomer fractions and other k -times bonded fractions assuming some characteristics for the hydrogen bonding interactions, such as number of associating sites and structural orientation. − There are several literature studies on the topic, and numerous articles have presented comparisons of such monomer fraction data against model predictions, especially for alcohols and water for which such data are available. − Alcohols are typically modeled using two or three sites, while water and glycols are often modeled assuming four sites. Recently, molecular simulation studies have generated, in addition to monomer fractions, k -times bonded fractions − for alcohols and water.…”