In response to several inquiries over the past few years, I have undertaken the task of updating the thermodynamic properties of steam. It has been 25 years since the IAPWS first released SF95 so that this effort is long overdue. My goal is to extend the range of applicability up to 6000K and 150GPa, considerably above any existing formulation. The data on which to base this extension has been available since 1974. While I have not completed the task, I have made considerable progress. As some researchers have expressed an urgent need for this work, I am releasing preliminary results. All of the data plus an Excel AddIn are contained in the following archive http://dudleybenton.altervista.org/miscellaneous/AllSteam104.zip, which will be updated as the work progresses. There is an installer to facilitate selection and placement of the correct (32-bit or 64-bit) AddIn, although this is unnecessary, as the libraries (AllSteam32.xll and AllSteam64.xll) are included. The current implementation is piecemeal and not optimal, but it does function. When complete, I will also release the source code. The average error in calculated density (compared to experimental) for the 2930 data points from 18 studies (see spreadsheet H2O_PVT_data.xls) for the SF95 and 2020 formulations is 0.68% and 0.46%, respectively, The maximum error is more telling, at 267% and 40%, respectively, as shown in the attached figure. I welcome your discussion.
The 2020 formulation will be the first to meet the important criterion of having three-and only three-real, positive roots for every subcritical isotherm. Lack of this character (extra "humps" and roots; incorrect metastable and spinodal behavior) has been noted since Keenan, Keyes, Hill, and Moore in 1969, but has not been remedied until now.
The metastable states and liquid spinodal are shown in this figure. The isotherms are too close to see the vapor spinodal.
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