Density, speed of sound and derived thermodynamic properties of a synthetic natural gas

Densities (ρ) and speed of sound (SOS) of a synthetic natural gas (∼88 mol% methane) were determined simultaneously at temperatures between 323 and 415 K and pressure up to 58 MPa. Densities and speed of sound were measured using a high pressure and high temperature Vibrating Tube densitometer (VTD) and an in-house acoustic cell, respectively. Moreover, to extend the PρT measurements to a wider range of temperature, isochoric measurements were conducted in a temperature range of 210–270 K.

The AGA8-DC92, GERG-2008, SBWR and PR-78 equations of state (EoS) were used to evaluate the experimental data. Finally, the SBWR EoS was tuned on the experimentally measured density to determine other thermodynamic properties such as isobaric heat capacity (Cp), isochoric heat capacity (Cv) and Joule-Thomson coefficients (μJT).