Experimental study and thermodynamic modeling of solid-liquid equilibrium of binary systems: Dodecane-tetradedcane and tridecane-pentadecane for cryogenic thermal energy storage

In the present work, the equilibrium phase behaviors and thermal characteristics (phase diagrams, enthalpies, melting/freezing temperatures) of the binary systems dodecane-tetradedcane (C12H26-C14H30) and tridecane-pentadecane (C13H28-C15H32) were experimentally investigated to employ the potential PCMs for cryogenic applications. In addition, the phase diagrams were theoretically obtained by using both the ideal and non-ideal thermodynamic models. Results show that the compositions of eutectic points appear at 18 wt% C-14 for the C-12-C-14 system and 10 wt% C-15 for the C-13-C-15 system. The specific eutectic compositions of these two systems have satisfied enthalpies (158.0 J/g for C-12-C-14 and 143.1 J/g for C-13-C-15 in the melting process), slight supercooling (03 C for C-12-C-14 and 0.4 C for C-13-C-15), minor hysteresis (3.9 degrees C for C-12-C-14 and 2.2 C for C-13-C-15) and superior thermal stability. Therefore, they are very attractive as the candidate PCMs in cryogenic energy storage systems. Moreover, the melting temperatures calculated by the theoretical models agree well with the experimental data. Especially for the non-ideal solubility model, the mean relative deviations are only 4% for the C-12-C-14 system and 8% for the C-13-C-15 system, respectively. (C) 2019 Elsevier B.V. All rights reserved.