A comparative study of PR, SRK, PC-SAFT, PρT-SAFT, and GERG-2008 equations of state for predicting the density and speed of sound of hydrogen-natural gas blends

Hydrogen plays a pivotal role as an energy carrier for a sustainable, low-carbon future, offering significant potential to decarbonize multiple sectors of the energy system. The precise thermodynamic modeling of hydrogen-natural gas blends is essential for their integration into existing energy infrastructure. This study provides a comparative analysis of five different equations of state (EoSs), including Soave-Redlich-Kwong (SRK), Peng-Robinson (PR), PC-SAFT, PρT-SAFT, and GERG-2008, for predicting the density and speed of sound of binary, ternary, and quinary mixtures containing hydrogen and key natural gas components, including hydrocarbons, carbon dioxide, carbon monoxide, nitrogen, and water. All calculations were performed without binary interaction parameters to assess the inherent predictive capabilities of each model. The results show that GERG-2008 and SAFT-based models, particularly PρT-SAFT, provided the highest accuracy, while cubic models exhibited lower accuracy. These findings highlight SAFT-type EoSs as reliable predictive tools for H₂-NG systems.