Lowered total solidification time and increased discharge rate of reduced graphene oxide-solar salt composites: Potential for deployment in latent heat thermal energy storage system

Solar salt is a useful energy storage medium and a heat transfer fluid for concentrated solar thermal applications. The present work explores the use of reduced graphene oxide (rGO) nanostructures as an additive to solar salt, to improve its thermophysical properties. Reduced graphene oxide nanostructures at weight fractions of 0.125 wt% and 0.5 wt% were added to the solar salt, leading to rGO-solar salt composites. The thermophysical characterization experiments revealed that the specific heat in the 0.5 wt% rGO-solar salt nanocomposite was elevated by 6% over the temperature range of 50-270 degrees C. The time required for complete solidification of 0.125 wt % and 0.5 wt% was reduced by 43% and 49%. In the discharge cycle, the heat transfer rate was amplified by 90% and 138% respectively for 0.125 wt% and 0.5 wt% rGO-solar salt nanocomposites, attributable to thermal conductivity enhancement, specific heat augmentation and heterogeneous nucleation. Thus, rGO-solar salt composites are suitable for use as latent heat thermal energy storage medium in solar thermal applications.