Approaches for Developing Thermodynamic Equations of State for Strong Electrolytes Based on the Pitzer Equations
Abstract
Nearly 50 years after their original publication, the Pitzer equations have been adopted for use more widely than any other thermodynamic modelling framework for aqueous electrolyte solutions.
This is due in part to the relative simplicity with which diverse thermodynamic properties of aqueous electrolyte solutions can be correlated in a single model.
Indeed, one of the key strengths of the Pitzer equations is their flexibility to cover broad ranges of pressure and/or temperature when suitable empirical terms are chosen for inclusion.
However, due to the lack of a strong theoretical foundation, the number of adjustable parameters required – and number of data required to regress those parameters – can be worryingly large.
Although satisfactory fits can be achieved when the ranges of conditions are chosen carefully and when sufficient data are available to constrain the regression, the fits obtained tend otherwise to be unsatisfactory if the data have gaps and other deficiencies.
Too frequently, the flexibility of the Pitzer equations manifests in violations of known thermodynamic behaviour. Strategies for overcoming some of the limitations of the Pitzer equations and achieving robust thermodynamic equations of state will be discussed in this seminar.
Dr Darren Rowland is a Postdoctoral Research Fellow in the Fluid Science and Resources Division at the University of Western Australia in Perth, Western Australia.
He has been in this position since 2016 and was previously at Murdoch University, also in Perth. Since 2008 he has been one of the lead developers of the Joint Expert Speciation System (JESS).
His work has focussed primarily on describing the thermodynamics of aqueous electrolyte solutions. However, in recent years his research scope has broadened to include natural gas mixtures, refrigerant mixtures and other industry-oriented projects.
Darren is the Chief Investigator on the Australian Research Council Discovery Project ‘Deep Ocean Thermodynamics and Climate Change’ which commenced in 2019.