Variable-Range PC-SAFT Parametrization for Accurate Modeling of Caloric Properties, Critical Temperature, and Critical Pressure: Normal Alkanes and Hydrogen

Abstract

A variable-range parametrization approach is proposed for PC-SAFT, and tested on hydrocarbons, hydrogen, and their mixtures. The soft-repulsion range parameter, which is usually set to 0.12, is relaxed, introducing one additional adjustable parameter. This modification provides powerful flexibility, improving accuracy for caloric properties, critical temperature (T_c), and critical pressure (p_c). For hydrocarbons, this approach significantly improves accuracy for speed of sound, T_c, and p_c, while maintaining accuracy for other properties. For hydrocarbon mixtures, the model demonstrates predictive capabilities for vapor–liquid equilibria (VLE) without any binary interaction parameters. For hydrogen, this approach significantly improves accuracy for vapor pressure, saturated liquid density, T_c, and p_c, although it does not improve results for caloric properties like for hydrocarbons. The hydrogen parameters are determined based on pure hydrogen properties and (hydrogen + methane) VLE. The approach demonstrates good predictive capabilities for mixture VLE when extended to other temperature and other (hydrogen + alkane) mixtures.