Calculation of the thermodynamic properties of water using the IAPWS model

Beginning 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. This new model, termed IAPWS-IF97, was adopted beginning in 1997, but an evaluation and changeover period was recommended before replacing the current model which had been developed in the 1960's (IFC-67). The latter model had been used for 30 years for the calculation of thermodynamic properties of water for industrial, scientific, and academic applications. 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. 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.