Correlation for the second virial coefficient of water

A new correlation has been developed to represent the second virial coefficient of water (H2O) as a function of temperature. The formulation was fitted to experimental data, both for the second virial coefficient itself and for a quantity related to its first temperature derivative, at temperatures between approximately 310 and 1170 K. The high-temperature extrapolation behavior was guided by results calculated from a high-quality intermolecular pair potential. The new correlation agrees well with the experimental data deemed to be reliable, and at high temperatures is a significant improvement over the best previous formulation. (C) 2004 by the U.S. Secretary of Commerce on behalf of the United States. All rights reserved.