Professor Estela’s research involves developing accurate equations of state (EOS) for technical applications in the chemical and process industries, particularly, for polar fluids, such as alcohols, carboxylic acids, amines, refrigerants, and mixtures of those fluids. This entails, the development of shape-factor models for use in extended corresponding states models (ECS) based on a reference EOS, and the development of Helmholtz plus association models for polar fluids. High-accuracy reference data and state-of-the-art optimization algorithms are applied in the EOS development. The significance of this work stems from obtaining accurate mathematical representations of the thermodynamic surfaces (i.e. EOS), which in turn enable the systematic calculation of thermodynamic properties of interest for practical applications in the chemical and process industries, e.g. model-based process control and simulation.