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In this study, a molten salt-based high temperature nanofluid is explored for solar thermal energy conversion applications. The efficacy of the nanofluid as a heat transfer fluid (HTF) in concentrating solar power systems is explored in this study. The molten salt can enable higher operating temperature resulting in enhancement of the overall system efficiency for power generation (using, for example, a Rankine cycle or Stirling cycle). However, the usage of the molten salt as the HTF is limited due to their low specific heat capacity values (compared with, for example, water or silicone oils). The low specific heat of molten salt can be enhanced by doping small amount of nanoparticles. Solvents doped with minute concentration of nanoparticles are termed as "Nanofluids." Nanofluids are considered as attractive coolants for thermal management applications due to their anomalously enhanced thermal properties (compared with the neat solvent).

The aim of this study is to explore the anomalous variation of thermo-physical properties of aqueous nanofluids. The specific heat of three water-based nanofluids containing silicon dioxide (SiO₂), titanium dioxide (TiO₂), and aluminum oxide (Al₂O₃) nanoparticles were measured using a differential scanning calorimeter (DSC). Measurements were performed over a temperature range of 30°C - 80°C which was chosen to be between melting point and boiling point of water. The experiments were implemented with different sizes of nanoparticles to investigate the effect of the size of nanoparticles on the specific heat of nanofluids. The specific heat of the nanofluids was plotted as a function of the diameter of nanoparticles and the mass concentration of nanoparticles. The results indicate that the specific heat of aqueous nanofluids decreases as the mass concentration of nanoparticles increases from 0.5% to 20%.