Hybrid nanofluids based on WSe2-WO3 and a siloxane-based fluid with application in concentrated solar power

• Nanofluids using a linear silicone fluid as base fluid were successfully prepared. • The base fluid used is an environmentally-friendly heat transfer fluid. • Increases of about 5% and 6% in specific heat and thermal conductivity were found. • Enhancement of about 19% in heat transfer coefficient was found. Improving the efficiency of renewable energies to meet the growing demand for energy is one of the main goals of the research community. In this sense, concentrated solar power plants are a research line of interest at the present time. Therefore, in this work, hybrid nanofluids were prepared based on WSe 2 -WO 3 nanosheets synthesized in our laboratory and a silicon oil-based fluid. These were widely characterized to determine whether the efficiency of the heat transfer processes occurring in this kind of plants can be improved. Thus, temporal physical stability was analysed, the nanofluids reaching a stability after several days that was maintained for over 40 days. Once stable, measurements were taken of the properties of interest of the nanofluids, namely density, surface tension, dynamic viscosity, isobaric specific heat and thermal conductivity. The density, surface tension and dynamic viscosity values for the nanofluids did not change significantly with respect to the base fluid. Their isobaric specific heat was improved by 5 %, while their thermal conductivity increased by about 6 %. All the properties measured were used to estimate a figure of merit for the application of nanofluids in concentrating solar power plants. Enhancements of about 19 % were found for two nanofluids, suggesting they are a promising option for use as heat transfer fluids in CSP-PTC plants.