Thermodynamic modelling of near-critical solutions

The challenge of modeling the properties of near-critical systems requires the use of different approaches in order to describe their strong variations with conditions, the variety of different and complex substances that can be present, and the difficulty of obtaining reliable data. This paper describes some approaches that lead to relatively simple descriptions for phase equilibrium and volumetric properties at low solute concentrations as well as suggests methods for solute–solute effects based on Fluctuation Solution Theory.