Prediction of the CH4-CO2 mixture properties using SAFT-VR Mie equation of state and molecular dynamics simulations.

This paper conducts a computational investigation of the phase behaviour of $ \textrm{C}{\textrm{H}_4} $ C H 4 - $ \textrm{C}{\textrm{O}_2} $ C O 2 binary system, utilising the SAFT-VR Mie equation of state alongside molecular dynamics (MD) simulations. Molecular parameters for pure $ \textrm{C}{\textrm{H}_4} $ C H 4 and $ \textrm{C}{\textrm{O}_2} $ C O 2 compounds were obtained by fitting the SAFT-VR Mie EOS to vapour pressure and saturated liquid density experimental data. The research first validates the SAFT-VR Mie EOS on thermodynamic properties and vapour–liquid equilibria for different compositions, pressures, and temperatures of pure $ \textrm{C}{\textrm{H}_4} $ C H 4 , $ \textrm{C}{\textrm{O}_2} $ C O 2 , and $ \textrm{C}{\textrm{H}_4} $ C H 4 - $ \textrm{C}{\textrm{O}_2} $ C O 2 mixtures with the newly extracted parameters. The study confirms the EOS's accurate prediction of coexistence properties, including pressure, density, and phase-equilibrium curve. MD simulations were performed using the LAMMPS software package, with Mie force field parameters derived from this study for non-bonded interactions. Simulations were conducted using three other force fields (OPLS-UA, UFF, and GAFF) to compare their performance with our approach. The simulation results were compared to laboratory data, or REFPROP, in the absence of laboratory data. The results showed a relatively good agreement, indicating that combining SAFT-VR Mie EOS and MD simulations is a reliable predictive tool for designing gas processing and gas storage applications involving $ \textrm{C}{\textrm{H}_4} $ C H 4 - $ \textrm{C}{\textrm{O}_2} $ C O 2 mixtures. This approach also mitigates the need for expensive and hazardous high-pressure laboratory techniques. [ABSTRACT FROM AUTHOR]