Preparation and Properties of Stearic Acid-Acetanilide Eutectic Mixture/Expanded Graphite Composite Phase-Change Material for Thermal Energy Storage

In this study, a series of binary mixtures of stearic acid (SA) and acetanilide (AA) at various mass fractions were prepared. A novel binary mixture of SA and AA in the ratio of 81.0:19.0 mol% is shown to be an eutectic mixture with melting temperature of 342.45 ± 0.25 K, melting latent heat of 220.04 ± 10.02 J·g-1. In order to improve the thermal properties of SA-AA eutectic mixture so as to obtain a better composite phase change materials (CPCM) with high thermal conductivity, large heat storage capacity, good thermal stability and reliability for heat energy storage, expanded graphite (EG) at different mass fractions is added into SA-AA eutectic mixture. The results exhibited it remarkable energy storage capacity with a latent heat of CPCM of 176.14 J·g-1 compared to most of the organic eutectic mixture composite. The thermal conductivity of the CPCM was enhanced by 14.5 times comparing to SA-AA eutectic mixture. And the thermo-physical properties of the SA-AA/EG CPCM after 100 accelerated thermal cycles were slightly decreased which did not distinct influence on heat storage. Thus, the prepared SA-AA/EG CPCM is a promising material for latent heat storage systems.