Accurate (p, ρ, T, x) Measurements of Hydrogen-Enriched Natural-Gas Mixtures at T = (273.15, 283.15, and 293.15) K with Pressures up to 8 MPa

Abstract

Accurate (p, ρ, T, x) measurements of three hydrogen-enriched natural-gas mixtures were carried out at T = (273.15, 283.15, and 293.15) K with pressures up to 8 MPa using a two-sinker densimeter. The relative expanded combined uncertainty (k = 2) in density was 0.02 %. To make up the mixtures under study, a 21-component high-calorific natural gas taken from a pipeline in Germany was blended with hydrogen to compositions of approximately (0.05, 0.10, and 0.30) mole fraction hydrogen. Comparisons of the measured densities with values calculated from the GERG-2008 and the AGA8 equations of state for natural gas mixtures are presented. The densities calculated with the equations of state are generally in very good agreement with our measured values and the limited available literature data. For the natural-gas mixtures containing hydrogen mole fractions of up to 0.10, relative deviations in density are essentially smaller than 0.05 %. Relative deviations of up to 0.1 % were observed for the natural-gas mixtures containing a hydrogen mole fraction of 0.30. This result suggests that both equations of state are suitable for hydrogen-enriched natural-gas mixtures in the investigated temperature- and pressure-range.