Improved thermal properties of stearyl alcohol/high density polyethylene/expanded graphite composite phase change materials for building thermal energy storage

Form-stable phase change materials (FSPCM) with high thermal energy storage capacity and thermal conductivity were manufactured by adding expanded graphite (EG) into stearyl alcohol (SAL) and high density polyethylene (HDPE) mixtures. In the composites, HDPE was used to prevent SAL leakage, and EG was not only a supporting material just like HDPE but also a thermal conductivity promoter. The influences of EG on the thermal properties of the SAL/HDPE phase change materials were investigated with a series of measuring means. Several lines of evidence showed that SAL and HDPE were mixed uniformly and EG was evenly dispersed in the SAL/HDPE composites. Approximately constant melting temperatures of FSPCM at around 57°C and high latent heat of at least 200kJ/kg were presented by the differential scanning calorimeter (DSC). It was found that the leakage rate of the SAL phase change materials decreased obviously when EG was added into the FSPCM. Furthermore, the thermal conductivity of FSPCM with 3% EG could increase up to 0.6698W(mK)-1 while thermal conductivity of FSPCM without EG was only 0.1966W(mK)-1. Finally, the FSPCM with EG could provide considerable thermal energy storage capacity and high thermal conductivity for latent heat storage.