Preparation and thermal characterization of capric–myristic–palmitic acid/expanded graphite composite as phase change material for energy storage

• Ternary eutectic mixture of capric–myristic–palmitic acid (CA–MA–PA) was prepared.
• A novel composite PCM of CA–MA–PA/EG was prepared.
• The optimum absorption of CA–MA–PA in CA–MA–PA/EG composite PCM is 92.86 wt%.
• The thermal conductivity and energy store rate of CA–MA–PA/EG were enhanced.
• The prepared CA–MA–PA/EG had a good thermal reliability.

Capric–myristic–palmitic acid ternary eutectic mixture (CA–MA–PA) was prepared as phase change material (PCM). A novel composite PCM of CA–MA–PA/expanded graphite (EG) with an optimum mass ratio (CA–MA–PA:EG=13:1) was prepared by uniformly absorbing CA–MA–PA into the porous network structure of the EG. The melting and freezing temperatures of CA–MA–PA/EG composite PCM were measured by differential scanning calorimeter as 18.61 °C and 16.58 °C, respectively, while the melting and freezing latent heats were 128.2 J/g and 124.5 J/g, respectively. The thermal conductivity of the CA–MA–PA/EG composite PCM was measured as 3.67 W/m K and thus the thermal storage and release rates were significantly increased. The thermal cycling test results showed that CA–MA–PA/EG composite PCM has a good thermal reliability. All the above results show that the CA–MA–PA/EG composite PCM is a potential solution for latent heat storage system.