Generalised Equations of State

Abstract

In the preceding section it was shown that state-of-the-art technical equations of state with simultaneously optimised functional form are numerically very stable and that they have surprising predictive capabilities. Such equations disprove common teachings which say that empirical equations of state should only be used in regions where they were fitted to a sufficiently dense set of accurate experimental data. However, even equations of state with simultaneously optimised functional form are bound to fail when fitted either to extremely small data sets or to small data sets with large inconsistencies. Thus, thermodynamic property models with further restricted numerical flexibility and with increased predictive capabilities are still needed to describe the broad variety of substances which is relevant for instance for applications in the chemical or petrochemical industry¹ An immeasurable multitude of models and equations of state has been developed either to fulfil the corresponding technical demands, or, more often, to advance the scientific search for the physically “true” description of the thermodynamic properties of fluids.