Innovative and cost-effective nanodiamond based molten salt nanocomposite as efficient heat transfer fluid and thermal energy storage media

Abstract

Novel and efficient molten salt nanocomposites as heat transfer nano-fluids and thermal energy storage materials have been developed. Cost-effective detonation nanodiamonds (NDs) of an average particle size of 10 nm were uniformly dispersed in binary nitrate molten salt using the ultrasonication process to achieve well dispersion of NDs. NDs mass loadings were varied and optimized, furthermore, the optimized mass loading of NDs was dispersed using solid state method for comparison. The thermo-physical properties of the developed ND-molten salt nanocomposites were studied in terms of melting point temperature, thermal stability temperature, thermal conductivity, volume heat capacity and thermal diffusivity and were enhanced in terms of their applications as heat transfer nano-fluids and thermal energy storage media. Therefore, melting point was reduced by 16 °C and the thermal stability was improved by 35 °C displayed enhanced temperature range compared to base binary molten salt. On other hand, the thermal conductivity and volume heat capacity were significantly improved achieving enhancement by 93 and 38% respectively, compared to base binary molten salt. Furthermore, the thermal diffusivity of developed ND based molten salt was enhanced by 43% compared to blank molten salt recorded superior values among reported nano-fluids. The surface morphology and dispersion of NDs in binary nitrate molten salt was studied and visualized using SEM and TEM.