Thermodynamic Properties of Fluids from Speed of Sound: Integration Along Isentropes

Abstract

The equations connecting speed of sound with other thermodynamic properties of gases and liquids, suitable for numerical integration with respect to temperature, density, and pressure, along isentropes, are derived. Algorithms of their solution are given too. They are tested with several substances (e.g., Ar, N2, O2, CH4, CO2, and H2O) in wide ranges of pressure and temperature. Average absolute deviation of thermal properties is 0.0129% in supercritical gaseous phase, 0.0308% in transcritical gaseous phase, and 0.0009% in liquid phase. Corresponding deviations of caloric properties are 0.1706%, 0.1863%, and 0.0702%, respectively.