Thermodynamic model for predicting the precipitation temperature of waxes using the activity model at high pressures

A new thermodynamic model for predicting solid–liquid equilibria (SLE) of paraffinic hydrocarbons in binary and multicomponent systems has been developed. The model employs the ideal solution theory for the liquid phase and the predictive Wilson activity model for the solid phase, thereby avoiding the use of cubic equations of state. The model accurately predicts the wax disappearance temperature (WDT) over a wide pressure range (from atmospheric pressure up to 300 MPa). Validation against more than 320 experimental data points, including pure components, binary mixtures, and multicomponent systems, shows excellent agreement, with average absolute deviations of 1.56 K for binary mixtures and 0.81 K for light–heavy hydrocarbon systems. The approach offers a reliable tool for modeling wax formation in pipeline and reservoir conditions.