A formulation for the relative permittivity of water and steam to high temperatures and pressures evolved using genetic programming

The relative permittivity (or static dielectric constant) of water and steam has been experimentally obtained from a relatively wide range of temperatures and pressures. A suite of functions for predicting the relative permittivity in four distinct thermodynamic regions is evolved using genetic programming. A data set comprised of all of the most accurate relative permittivity values, along with temperature, pressure, and density values, is used for this task. The accuracy of these functions is evaluated by comparing the values for the relative permittivity calculated using the evolved function and the values calculated using the latest formulation of Fernandez et al, to the aforementioned data set. In all regions, the newly evolved function performs comparably to or better than the most current formulation in terms of difference between calculated and experimental values for the dielectric constant. This research represents a successful application of artificial evolutionary techniques to relative permittivity prediction in physical chemistry.