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- GERG-2008 equation of state (3)
- Density measurements (2)
- Equations of state (2)
- Hydrogen-enriched natural gas (2)
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- Binary mixtures CO2 + O2 (1)
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Experimental characterization of the thermodynamic behavior of multicomponent gas mixtures of accurately known composition with traceability to National Standard is of great importance for testing the current reference equation of state (EoS) for natural gases and related mixtures, GERG-2008. Natural gas composition may change considerably due to the diversity of origins, or the possibility to incorporate hydrogen, biomethane or other non-conventional energy gases.
In this work, density measurements for three synthetic mixtures, representing two biomethane mixtures and a typical natural gas composition, are presented. Results are compared to the current reference EoS for natural gases and related mixtures, i.e., GERG-2008 and AGA8-DC92.
The GERG-2008 and AGA8-DC92 equations of state enable the calculation of thermal and caloric properties for natural gases and other related mixtures consisting of up to 21 pure components. Experimental characterization of the thermodynamic behavior of gas binary mixtures is of great importance because most of the binary systems were taken into account by using adjusted reducing functions for density and temperature. Only for those binary mixtures for which sufficient accurate experimental data were available, specific departure functions were developed. For the binary mixture methane-helium no departure function was developed so far.
This work studied the thermodynamic behavior of two gravimetrically prepared methane-helium binary mixtures through accurate (p, ρ, T) experimental data obtained by using a single-sinker densimeter with magnetic suspension coupling.
Experimental characterization of the thermodynamic behavior of multicomponent gas mixtures of accurately known composition is of great importance for testing the current reference equation of state for natural gases and related mixtures, GERG-2008. Natural gas composition may change considerably due to the diversity of origins, or the possibility to incorporate hydrogen, biogas or other non-conventional energy gases.
Thus, the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology (CCQM) of the Bureau International des Poids et Mesures (BIPM) launched a key comparison on primary standard mixtures for natural gases of this particular characteristics. One mixture is a hydrogen-enriched natural gas mixture (13 components, x(H2) = 0.03) with low calorific value to facilitate support to power-to-gas applications, which often involve blending hydrogen with natural gas. The other mixture resembles a typical liquefied natural gas (“LNG”, 9 components) with high calorific value.
On the way to a low carbon economy mixtures containing carbon dioxide become increasingly important. Processing of such gas mixtures requires reliable thermodynamic models that can accurately describe the state of matter over an extended range. Mixtures with oxygen for example, are frequently encountered in carbon capture and storage (CCS) processes.
This work reports new experimental (p, rho, T) data at T = (250 to 375 K) and up to a maximum pressure pmax = 20 MPa for five binary (CO2 + O2) mixtures which cover the entire composition range.
Hydrogen-enriched natural gas, H2NG is a mixture of natural gas and H2 that can be used on existing natural gas infrastructure with little or even no modification to be applied H2NG is thus an option in the transition from fossil fuels to a hydrogen economy, as it can reduce greenhouse gas emissions and can accelerate the adoption of H2 from renewable sources. Theoretically, H2 can be mixed with NG in any ratio, but H2NG mixtures with up to 20 vol-% of H2 represent the most realistic near term option due to technical and economic reasons. The addition of H2 to natural gas alters the thermodynamic properties of the mixture, which affects its transport, storage, and combustion characteristics. In this work, we present experimental density measurements for different H2NG mixtures, performed with a high-precision single sinker densimeter from 250 to 350 K and up to 20 MPa. The mixtures were prepared gravimetrically according to ISO 6142-1 for maximum precision in their composition.