Investigating the effect of graphene on eutectic salt properties for thermal energy storage.

• Low temperature molten salt was synthesized for thermal energy storage. • Graphene doped low temperature molten salt shows enhancement in heat capacity and thermal conductivity. • No Alteration in thermal stability before and after doping graphene in molten salt. • Good prediction of heat capacity and thermal conductivity by various models except Nan's model. Enhancement of heat capacity and thermal conductivity with the dispersion of graphene nanoparticles into low-temperature eutectic salt was investigated. Three different nanoparticle concentrations (0.01, 0.05 & 0.1 wt. %) were dispersed into a eutectic salt mixture composed of 5.66% NaNO 3 , 21.25% KNO 3 , 24.75% Ca(NO 3) 2 , 41% CsNO 3 , & 7.34% LiNO 3 by weight. The results show that the graphene doping resulted in enhanced heat capacity ranging from 5 to 13%, whereas thermal conductivity increased marginally by ˜3%, with respect to graphene concentration. Various theoretical models were tested to predict the thermal conductivity and heat capacity of the graphene-doped eutectic salt. The Maxwell and Hamilton-Crosser thermal conductivity models showed good agreement with experimental results, with a deviation of ±3%, while Nan's thermal conductivity model over-predicted the thermal conductivity value. The conventional heat capacity equation fits well with the experimental data, with deviation <14%. [ABSTRACT FROM AUTHOR]