Preparation, thermal properties and thermal reliability of a novel mid-temperature composite phase change material for energy conservation

Condensation heat of air-conditioner in household and public is a kind of indispensable waste heat, which is necessary to recover and reuse it. Herein, phase change material is widely used in exhaust heat recover and storage. In the present work, expanded graphite(EG) was introduced to stearic acid-acetamide(SA-AC) eutectic mixture, aiming at obtaining composite phase change material(CPCM) with high thermal conductivity, large heat storage capacity and favorable thermal repeatability for efficient heat recover. DSC results exhibited its remarkable energy storage capacity with a latent heat of CPCM of 186.8 J g−1 compared to most of the organic eutectic composite. The second law of thermodynamics was used to explain the phase change characteristics of the SA-AC/EG CPCMs corresponding to the pristine SA-AC eutectic mixture. The thermal conductivity of the CPCM was enhanced by 17.59 times comparing to pristine SA-AC. The results of thermal conductivity and infrared thermal images confirmed the CPCM possessed prominent heat storage efficiency. The thermo-physical properties of the SA-AC/EG CPCM after 500 accelerated thermal cycles were slightly decreased which did no distinct influence on heat storage. Due to the low cost and remarkable properties, the SA-AC/EG CPCM was a promising candidate for energy conservation by condensation heat recovery of air-conditioner.