Evaluation of the Thermal Properties of Ternary Mixtures of Fatty Acids for Green Thermal Energy Storage Application

In the present study, experimental and thermodynamic aspects of solid-liquid equilibrium were evaluated for ten ternary fatty acid mixtures formed by capric, undecylenic, pentadecylic, margaric, and stearic acids as potential phase change materials (PCMs). The latent heat and melting temperature of the ternary fatty acids mixtures were determined by data from differential scanning calorimetry (DSC). Furthermore, the coefficients of the non-random equation of two liquids (NRTL) thermodynamic model were calculated using quasi-binary mixing law to correlate the liquidus line of solid-liquid equilibrium for understudying ternary mixtures. The comparison between the results of the proposed thermodynamic model with the experimental data represents the average absolute deviations less than 1%, which validates the correlated thermodynamic model. The melting temperature of ternary mixtures of fatty acids studied in this study was in the range of 281-315 K with melting enthalpies of 26.09 and 45.74 kJ.mol-1, which indicated that these mixtures have good potential to utilize as low-temperature thermal energy storage.