Realgase

Realgase is a term used in physics and chemical engineering to describe a framework for modeling real-gas behavior. It denotes a family of equations of state and associated computational methods that extend the ideal gas law to account for intermolecular forces and finite molecular size. The name combines real and gas to emphasize the departure from idealized behavior observed under high pressures or near condensation.

Historically, Realgase approaches emerged as engineers and scientists sought more accurate predictions of PVT properties than those provided by the ideal gas law. The concept encompasses a range of EOS, including van der Waals, Redlich-Kwong, Soave-Redlich-Kwong, Peng-Robinson, and newer cubic formulations, as well as corresponding mixing rules for multicomponent systems. These models express a state equation relating pressure, temperature, and molar volume, with parameters calibrated from critical properties and experimental PVT data.

In applications, Realgase models are used in petroleum and natural gas processing, petrochemical design, refrigeration, and high-pressure combustion simulations. They support process simulations, phase equilibrium calculations, and property estimation for multicomponent mixtures across wide temperature and pressure ranges.

Limitations and ongoing work: Realgase models approximate real behavior and may require careful selection of EOS and parameters for a given system. They can be computationally intensive for large mixtures or near phase transitions, and no single EOS is universally best. Ongoing research focuses on improved mixing rules, molecular-based EOS, and data-driven corrections.

See also: real gas, equation of state, Peng-Robinson, Redlich-Kwong.