Specific heat capacity, viscosity, and thermal stability of carbonate-based molten salt nanofluids

•Li2CO3-Na2CO3 nanofluid showed higher heat capacity than Li2CO3-K2CO3 nanofluid.•Li2CO3Na2CO3 nanofluid showed less viscosity than Li2CO3-K2CO3 nanofluid.•Both pure eutectics and Li2CO3-K2CO3 nanofluid showed no thermal decomposition up to 600 °C.•The Li2CO3-Na2CO3 nanofluid decomposed after 470 °C at an average rate of 0.0017 mg/°C. Li2CO3-K2CO3 and its nanofluids have been widely studied for thermal energy storage media in concentrated solar power due to their largely enhanced specific heat capacity values. On the other hand, Li2CO3-Na2CO3 and its nanofluids have not been explored although Li2CO3-Na2CO3 has a larger specific heat capacity than Li2CO3-K2CO3. Therefore, in this study, we synthesized Li2CO3-Na2CO3 and Li2CO3-K2CO3 pure salt eutectic mixtures and their nanofluids. These mixtures were then tested for three distinct thermophysical properties, specific heat capacity, viscosity, and thermal stability. The obtained experimental results of all four systems were evaluated for use as thermal energy storage media in concentrated solar power.