A precise method to measure the specific heat of solar salt-based nanofluids

A novel material has been developed for thermal energy storage at high temperatures (>300 °C) with enhanced thermal transport and storage properties. It is considered more efficient than the current molten salts used in the concentrated solar power plants. It is composed of an inorganic salt doped with a small percentage of nanoparticles (NPs), which are claimed to increase the specific heat compared with that of the raw salt. Thus, a precise determination of this thermal property is essential to perceive this enhancement. The specific heat of solar salt (SS) and a mixture of SS with 1 mass% of alumina NPs have been measured by the differential scanning calorimetry (DSC) technique. An isothermal procedure based on modulated DSC has been established to perform the measurements. The influence of the type of crucible, the amount of sample inside the crucible and the presence of moisture on the scattering of the data has been studied. Reliable results with a low uncertainty (<10%) were achieved by the use of T-zero aluminium hermetic crucibles, the mass increment of analysed sample (30 mg) and the absence of moisture inside the crucibles.