Experimental study and thermodynamic modeling of solid-liquid equilibrium of binary and ternary mixtures formed by C₁₁H₂₄, C₁₂H₂₆ and C₁₄H₃₀ for cryogenic thermal energy storage

In this study, experimental investigations of solid-liquid phase diagram of binary and ternary mixtures formed by the C₁₁H₂₄, C₁₂H₂₆ and C₁₄H₃₀ were carried out to employ the potential phase change materials (PCMs) for cryogenic applications using the differential scanning calorimetry (DSC). In addition, the thermodynamic equilibrium was modeled employing the ideal model, and the Wilson and NRTL model were applied to correlate the liquidus line. The results show that the C₁₁-C₁₂ system exhibits a peritectic transition and the composition of possibly peritectic point is 60wt% C₁₂ with the temperature of 251.65 K. The compositions of the eutectic points appear at 10wt% C₁₄ for C₁₁-C₁₄ system and 18wt% C₁₄ for C₁₂-C₁₄ system with eutectic temperatures of 246.85 K and 260.45 K, respectively. The C₁₁-C₁₂-C₁₄ ternary system presents two possibly eutectic points at compositions of 67wt% C₁₁/5wt% C₁₂ and 86wt% C₁₁/10wt% C₁₂ with eutectic temperatures of 246.45 K and 248.05 K, and has the slight supercooling (1.7 ˚C and 0.5 ˚C), indicating miscibility in liquid phase and immiscibility in solid phase. Moreover, the liquidus lines calculated by the theoretical models are in good agreement with the experimental results. The best predicted results of the ternary mixture and C₁₁-C₁₂ binary subsystem are obtained by the ideal model, with deviations of 0.75% and 0.58% respectively.