Abstract:
A universal equation of state is constructed in the near-critical and supercritical regions. For this, the virial series is modified by expanding the pressure into a series in powers of density along the straight line of the unit compressibility factor, which lies in the supercritical region. The leading coefficients of this modified expansion can be expressed in terms of the second coefficient and a universal equation of state can be obtained, which includes the quantities determined by the type of potential (the second virial coefficient, as well as the Boyle and critical parameters) and does not contain empirical constants. The critical parameters obtained using this equation of state for three model systems and a substance (methane) are in good agreement with the numerical simulation data and experiment.
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