Performance study of 1-octadecanol/modified expanded graphite composite phase change materials

We oxidised expanded graphite (EG) to produce graphene oxide (GO) using aqua regia, and modified graphene oxide (KGO) with a strong affinity for organic compounds was prepared by chemical modification of GO using the silane coupling agent 3-aminopropyltriethoxysilane (KH-550). By incorporating a small amount (x <= 3 wt%) of KGO into 1-Octadecanol (OD) as a thermal conductivity additive, OD/KGOx composite phase change materials (PCMs) with excellent overall performance were manufactured, characterization and performance testing of the composite PCMs were conducted before and after 200 thermal cycles. The results showed that KH-550 molecules chemically bonded with GO. As the proportion of KGO increases, the thermal performance of the composite PCMs gradually improves. When the addition of KGO was 3 %, the thermal conductivity of the PCMs increased by 125.5 % compared to the OD, with corresponding increases of 38.1 % in the heat storage rates and 45.3 % in the heat release rates. Respectively, the latent heat of some composite PCMs slightly increased after 200 cycling, reaching approximately 237-254 J/g. The slight differences in the thermal conductivity at both ends and in the rates of heat storage and release before and after cycling indicate the excellent dispersion and thermal cycle stability of the composite PCMs. The prepared novel composite PCMs exhibited significantly improved performance, offering a feasible solution for enhancing solar energy storage efficiency.