Contents - Index



Starting with EES version 10.364, keywords Steam, Water, Steam_IAPWS, and R718 all use the Steam_IAPWS property correlation.


Steam_IAPWS implements high accuracy thermodynamic properties of water substance with the 1995 Formulation for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use, issued by The International Association for the Properties of Water and Steam (IAPWS).  This correlation replaced the 1984 formulation of Haar, Gallagher, and Kell (NBS/NRC Steam Tables, Hemisphere Publishing Co., 1984) which is implemented in substance STEAM_NBS.  The new formulation is based on the correlations of Saul and Wagner (J. Phys. Chem. Ref. Data, 16, 893, 1987) with modifications to adjust to the International Temperature Scale of 1990. The modifications are described by Wagner and Pruss (J. Phys. Chem. Ref. Data, Vol. 31, No. 2, 387, 2002). 


This correlation provides accurate results for temperatures between 273.15 K and 1273.15 K at pressures up to 1000 MPa.  The formulation allows extrapolation of properties to 5000 K.  


Water also provides steam properties, but they use less accurate correlations which require significantly less computational effort.  Use Steam or Water for the properties of ice at temperatures below 0 C based on ice property information from Hyland and Wexler, Formulations for the Thermodynamic Properties of the Saturated Phases of H2O from 173.15 K to 473.15 K, ASHRAE Trans., Part 2A, Paper 2793, 1983.


Enthalpy and entropy values are referred to 0 for saturated liquid at 0 C.


The viscosity, and surface tension correlations for Steam_IAPWS are from:

J. Kestin, J.V. Sengers, B. Kangmar-Parsi, and J.M.H. Levelt Sengers, 

Thermophysical Properties of Fluid H2O 

J. Phys. Chem. Ref. Data, 13, 175 (1984).  


The thermal conductivity is determined from:

M. L. Huber, R. A. Perkins, and D. G. Friend, J. V. Sengers, M. J. Assael and I. N. MetaxaK. MiyagawaR. Hellmann and E. Vogel

New International Formulation for the Thermal Conductivity of H2O

J. Phys. Chem. Ref. Data 41, 033102 (2012); doi: 10.1063/1.4738955


Fluid Property Information