Thermodynamics Research Center / ThermoML | Thermochimica Acta

ABSTRACT

Phase equil. theory and the laws of thermodn. provide valuable tools for predicting the compn. and the thermal properties of eutectic mixts. In this work, we briefly review the predictions based on ideal mixts. We evaluate the accuracy of the models by comparing the predicted values of the compn., the melting temp. (Tmpt) and the enthalpy change (fusH) of binary mixts. of fatty acid phase change materials (PCMs), specifically as measured for decanoic - tetradecanoic acids, and dodecanoic - tetradecanoic acids and with values reported in the literature for other fatty acid eutectics. Although the phase diagrams depart from the ideal system (e.g., peritectic), there is, overall, reasonable agreement with the exptl. data, i.e., the thermodn. models can be a good starting point for the prediction of eutectic behavior in binary or higher order mixts. of org. PCMs. A computational tool based on these thermodn. models was developed in Microsoft Excel Kahwaji and White, [1] and used to calc. the compn., Tmpt and fusH of a total of 105 binary mixts. formed from 15 different fatty acid PCMs. The calcd. properties show that eutectics both extend the lower range of Tmpt and provide a wide range of new Tmpt values that are not otherwise available from individual fatty acids, hence considerably expanding the scope of applications of fatty acids as PCMs for thermal energy storage.