Accurate thermodynamic characterization of a synthetic coal mine methane mixture

• Accurate density data of a 10 components synthetic coal mine methane mixture are presented.
• Experimental data are compared with the densities calculated from the GERG-2008 equation of state.
• Relative deviations in density were within a 0.2% band at temperatures above 275 K.
• Densities at 250 K as well as at 275 K and pressures above 10 MPa showed higher deviations.

In the last few years, coal mine methane (CMM) has gained significance as a potential non-conventional gas fuel. The progressive depletion of common fossil fuels reserves and, on the other hand, the positive estimates of CMM resources as a by-product of mining promote this fuel gas as a promising alternative fuel. The increasing importance of its exploitation makes it necessary to check the capability of the present-day models and equations of state for natural gas to predict the thermophysical properties of gases with a considerably different composition, like CMM. In this work, accurate density measurements of a synthetic CMM mixture are reported in the temperature range from (250 to 400) K and pressures up to 15 MPa, as part of the research project EMRP ENG01 of the European Metrology Research Program for the characterization of non-conventional energy gases. Experimental data were compared with the densities calculated with the GERG-2008 equation of state. Relative deviations between experimental and estimated densities were within a 0.2% band at temperatures above 275 K, while data at 250 K as well as at 275 K and pressures above 10 MPa showed higher deviations.