It required division of the area of validity of its equations into five different regions due to the complexity of the behavior of the thermodynamic properties of water. The model was, however, was not easy to use. A great number of tables and diagrams existing in the literature, as well as computerized calculation programs were based on this model. Model IFC-67 was tested and recognized as reliable for the calculation of the thermodynamic properties of water. This model was developed from a variety of experimental data available for H 2O, which is the most abundant chemical compound in nature and also the most often used reagent in the chemical industry. In the decade of the 1960's a model was formulated for the calculation of thermodynamic properties of water for industrial use, and was known as the IFC-67 model.

Keywords: thermodynamic properties, water and steam, calculation algorithms

This paper presents the IAPWS-IF97 model in summarized form, and results obtained in applying it to the thermodynamic properties of water, including enthalpy, entropy, internal energy, and volume, in the states of compressed liquid, liquid-vapor equilibrium, and superheated steam, using calculation algorithms developed using common, universally available computational techniques. The new model is oriented toward facilitating calculations employing computers, improving accuracy, and improving consistency among the model's limiting regions as well as contributing towards improved process design and simulation. The latter model had been used for 30 years for the calculation of thermodynamic properties of water for industrial, scientific, and academic applications. Was recommended before replacing the current model which had been developed in the 1960's (IFC-67). This new model, termed IAPWS-IF97, was adopted beginning in 1997, but an evaluation and changeover period 2ġDepartment of Chemical Engineering, Engineering Faculty, Universidad de Antofagasta, Antofagasta, Chile,ĢDepartment of Chemistry, Basic Sciences Faculty, Universidad de Antofagasta, Antofagasta, Chile,īeginning in 2000 the International Association for the Properties of Water and Steam (IAPWS) recommended the use of a new model for calculation of the thermodynamic properties of water and steam. Soc., 51, Nº 2 (2006), pags: 891-900ĬALCULATION OF THE THERMODYNAMIC PROPERTIES OF WATER USING THE IAPWS MODEL

Steam properties table