Optimizing solar collector efficiency through nanofluid analysis and investigating the impact of particle concentration, and stability

The emission of greenhouse gases contributes to global warming, and adopting renewable energy can mitigate the reliance on fossil fuels, which currently account for 84.3% of global energy production. Solar thermal energy represents a significant renewable energy source, with solar collectors contributing 54.1% of the world's solar energy. However, the thermal properties of the liquids used in these collectors are suboptimal, and adding particles to the fluid can enhance absorption and thermal characteristics. Nanofluids refer to solid particles reduced to nanoscale sizes, and this study focuses on producing an Ag nanofluid through mechanical exfoliation and its comparative analysis with a GO nanofluid regarding radiation absorption. The results indicate that the Ag nanofluid outperforms pure water and performs similarly at lower concentrations. Specifically, temperature differences of 4-7 degrees C were observed for a simulated power of 1 unit, while the evaporation efficiency reached up to 40.8% for 200 and 500 ppm concentrations, compared to 28.6% for pure water. Moreover, under a radiation intensity of 60 units, the Ag nanofluid achieved the boiling temperature of the water after 85 s. In contrast, GO required at least 250 s, and pure water did not reach the boiling temperature within the 6-min study period. Thus, the Ag nanofluid holds promise as an effective nanofluid for direct absorption solar collectors due to its affordability, low toxicity, and comparable benefits to graphene.