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arXiv · 1903.11730

Speed of sound of pure water to 700 MPa and an equation of state to 2300 MPa

Olivier Bollengier·J. Michael Brown·George H. Shaw
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Abstract

Sound speeds of pure fluid water are reported between 0.1 and 700 MPa, from 353 K down to the melting curves of the ice phases. The 2 sigma precision and accuracy of the new sound speed measurements are close to 0.02%, with an estimated pressure accuracy of 0.04% up to 700 MPa. Using additional published measurements, a new equation of state is derived extending from 240 to 500 K and from 0.1 to 2300 MPa, covering much of the sub-critical domain of water up to the ice VI - ice VII transition. Analysis of measurements and construction of the equation of state are accomplished with a flexible computational thermodynamic framework based on local basis functions in the form of tensor b splines. Relative to IAPWS-95 (the most comprehensive representation available), improvements in the accuracies of density, sound speed and specific heat are observed above 100 MPa, particularly near the solid-fluid phase boundaries. Accurate thermodynamic properties for aqueous solutions under an increasing range of pressures, temperatures and compositions are needed to address a variety of technical and scientific challenges: the present study provides measurements essential for improving the high-pressure and low temperature representation of water.

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Olivier Bollengier, J. Michael Brown, George H. Shaw. 2019-03-27. Speed of sound of pure water to 700 MPa and an equation of state to 2300 MPa. https://arxiv.org/abs/1903.11730

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