A FORMULATION FOR THE STATIC PERMITTIVITY OF WATER AND STEAM AT TEMPERATURES FROM 238 K TO 873 K AT PRESSURES UP TO 1200 MPA, INCLUDING DERIVATIVES AND DEBYE-HUCKEL COEFFICIENTS

A new formulation is presented of the static relative permittivity or dielectric constant of water and steam, including supercooled and supe rcritical states, The range is from 238 K to 873 K, at pressures up to 1200 MPa. The formulation is based on the ITS-90 temperature scale. I t correlates a selected set of data from a recently published collecti on of all experimental data. The set includes new data in the liquid w ater and the steam regions that have not been part of earlier correlat ions. The physical basis for the formulation is the so-called g-factor in the form proposed by Harris and Alder. An empirical 12-parameter f orm for the g-factor as a function of the independent variables temper ature and density is used. For the conversion of experimental pressure s to densities, the newest formulation of the equation of slate of wat er on the ITS-90, prepared by Wagner and Pruss, has been used. All exp erimental data are compared with the formulation. The reliability of t he new formulation is assessed in all subregions. Comparisons with pre vious formulations are presented. Auxiliary dielectric-constant formul ations as functions of temperature are included for the saturated vapo r and liquid states. The pressure and temperature derivatives of the d ielectric constant and the Debye-Huckel limiting-law slopes are calcul ated, their reliability is estimated, and they are compared with exper imentally derived values and with previous correlations. All equations are given in this paper, along with short tables. An implementation o f this formulation for the dielectric constant is available on disk [A . H. Harvey, A. P. Peskin, and S. A. Klein, NIST/ASME Steam Properties , NIST Standard Reference Database 10, Version 2.1, Standard Reference Data Program, NIST, Gaithersburg, MD (1997)]. (C) 1997 American Insti tute of Physics and American Chemical Society.