Material preparation and heat transfer characterization of porous graphene aerogel composite phase change material

Due to the characteristics of high energy storage efficiency, large energy storage capacity and constant phase change temperature, organic phase change materials have been widely used in the field of thermal energy storage. However, organic phase change materials present a lower thermal conductivity which emerges as a critical limitation to the energy storage efficiency of latent heat thermal energy storage systems. To improve the thermal properties, the superior composite phase change materials of graphene aerogel impregnated paraffin wax were prepared in present study. Hydrothermal reaction method was used to prepare aerogel. Optimal conditions for aerogel preparation were identified as 140 °C/2.5 h/90%/(1:100) (140 °C is the hydrothermal working temperature of the reactor, 2.5 h indicates a treatment time, 90% is the solution occupying the reactor volume and 1:100 is the graphene oxide (GO)/water ratio in the solution). Furthermore, the addition of ethylenediamine and graphene nanoplatelets accelerated the reaction process, which required a hydrothermal treatment time by 50%. For the composite phase change material PW-GO/GNP-3 with a GO/GNP mass fraction of 4.4%, the thermal conductivity was 209.7% of that for the pure PW and the energy storage efficiency was still maintained at 91.60%. Meanwhile, the composite phase change material exhibits a leakage ratio of lower than 3.8%. In addition, based on the prepared composite phase change material samples, the phase change characteristics of phase change material in single cavity and three-cavities have also been examined. The synchronous phase change in three-cavities has been obtained by arranging the phase change material with low melting temperature in the cavity with low temperature, which requires the shortest melting time.