Equation of liquid, gas, and fluid state for methane

Abstract

Abstract Using methods and approaches, previously developed by the authors, a new fundamental low-parametric equation of state for methane (in the form of the reduced Helmholtz function) has obtained to describe the thermodynamic properties. It allows describing the thermal properties of gas, liquid, and fluid at pressures of up to 20 MPa with sufficiently high accuracy close to the experimental one (with the exception of the critical region). The sound speed and caloric properties of methane have been calculated without involving any caloric data, with the exception of ideal gas enthalpy. The values of speed of sound, isochoric heat capacity, and other thermodynamic properties obtained by calculations are in good agreement with the experimental data.