Jacobsen–Stewart reference equation

This is an empirical high-precision reference EOS, or rather an EOS template, for pure substances that covers the whole fluid range. The equation is a sum over products of powers of reduced density, reduced inverse temperature, and exponential terms; non-integer exponents are permitted.

The EOS is clearly an extension of the older Benedict–Webb–Rubin EOS and the Strobridge EOS. It was proposed almost simultaneously by Bender [1] and by Jacobsen and Stewart [2], and later optimized by Schmidt and Wagner [3].

Here the EOS has been implemented as a special case of the Wagner–Setzmann EOS.

The number of terms and the values of the (usually more than 50) coefficients and exponents depend on the substance. They were determined by careful data regression. The EOS can only be used for the substance for which this regression had been made.

The EOS should be used for metastable states; the behaviour for densities between the liquid and the gas density (at subcritical temperatures) is erratic.

adjustable parameters: 0

This *ThermoC* version contains JS equations of state for
benzene [4], ethanol [5], and hydrogen sulfide [6].

[1] E. Bender, *The calculation of phase equilibria from a thermal
equation of state applied to the pure fluids argon, nitrogen, oxygen and
their mixtures*, Verlag C. F. Müller, Karlsruhe 1973.

[2] R. T. Jacobsen, R. B. Stewart, *J. Phys. Chem. Ref. Data* 2 (1973)
757–922.

[3] R. Schmidt, W. Wagner, *Fluid Phase Equilib.* 19 (1985) 175–200.

[4] A. Fenghour, K. M. de Reuck, A. Elhassan, J. Kilner, and R. Craven,
*Proc. 17th IUPAC Conf. on Chemical Thermodynamics (ICCT-2002)*,
University of Rostock, 2002, 47–48 **[benzene]**.

[5] H. E. Dillon and S. G. Penoncello, *Int. J. Thermophysics*
25 (2004) 321–335 **[ethanol]**.

[6] N. Sakoda and M. Uematsu, *Int. J. Thermophysics* 25 (2004)
709–737 **[hydrogen sulfide]**.

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