Solid–liquid equilibria and non-isothermal crystallization kinetics of n-alkanes binary systems

Abstract

Paraffin wax containing n-alkanes has received significant attention in the field of thermal energy storage. The crystallization process is regarded as the main thermal discharging method, which has a profound influence on the thermal performances of paraffin wax. Herein, the phase diagrams of binary systems n-heneicosane + n-pentacosane (C21-C25) and n-pentacosane + n-octacosane (C25-C28) were measured. The results showed that the ordered form was replaced by the rotator form and ultimately transited into a liquid with increasing temperature. Jeziorny and Mo models were used to describe the non-isothermal crystallization process of C25, C21-C25 and C25-28. The effective crystallization activation energy (\(\Delta {E}_{\text{m}}\)) for the non-isothermal crystallization process of n-alkanes was analyzed using the differential isoconversional method of Friedman. The addition of C21 and C28 was found to have a positive effect on the nucleation; while, a negative effect on the growth process, representing negative net effect on crystallization rate.