Modeling of Solid Liquid Equilibrium for Tertiary Mixtures of Fatty Acid by Wilson Model

Pure and eutectic mixtures of fatty acids are desirable Phase Change Materials (PCMs) for low/medium Thermal Energy Storage (TES) applications because of their high density of energy storage, biodegradability, sustainability, and compatibility with existing systems. In the current study, thermodynamics and the experimental standpoint of phase equilibrium for 10 ternary mixtures of fatty acids were considered. In this regard, an approach based on the Wilson model was developed to predict the melting temperature of fatty acids to predict the eutectic points of ternary mixtures including Capric acid, Undecanoic acid, pentadecanoic acid, Margaric and Stearic acid. It indicated that the eutectic points were close to the melting temperature of lower density compounds and for Capric+Undecanoic+Pentadecanoic the melting point has the minimum values among the other nine mixtures and equals 281.0 °C. A comparison of the derivate activity model with the experimental data represented deviations of less than 1% between experimental and predicted values.