Ag-based nanofluidic system to enhance heat transfer fluids for concentrating solar power: Nano-level insights

One of the possible research lines for improving the Concentrated Solar Power (CSP) technology is the enhancement of the thermophysical properties of the Heat Transfer Fluids (HTF) used. This enhancement leads to reduce costs for producing electricity using this technology. So, this study presents the preparation of nanofluids in which Ag nanoparticles were added to a base fluid composed of a eutectic mixture of diphenyl oxide and biphenyl. The base fluid is a heat transfer fluid commonly used in concentrating solar power plants. The nanofluids were shown to have improved thermal properties, the heat transfer coefficient increasing by up to 6% compared with the base fluid. Thus, their use could lead to enhancements in the overall efficiency of CSP plants. Accordingly, nanofluids were prepared with varying nanoparticle concentrations and their properties were characterized, including their physical and chemical stability, viscosity, isobaric specific heat and thermal conductivity. In addition, molecular dynamic calculations were performed to reach a better understanding of the nanofluid system at a molecular level. The isobaric specific heat and thermal conductivity values followed the same experimental tendency. An analysis of the radial distribution functions (RDFs) and spatial distribution functions (SDFs) shows that there is a first layer of base fluid molecules around the metal in which the oxygen atoms play an important role. This first layer encourages the directionality of the movement in the heart of the nanofluid, which leads to enhanced thermal properties.