First approach on nanofluid-based solar still in high altitude for water desalination and solar water disinfection (SODIS)

In present study, performance of two nanofluid-based solar stills at the peak of Mount Tochal nearly 4000 m and city of Tehran during four consecutive days in July 2018 for the first time was examined. Silver nanofluid due to prominent advantages such as excellent optical properties, high thermal conductivity, and anti-bacterial characteristics at 0.04% weight of concentration was used. Since the rate of ultra-violet (UV) at the apex of Tochal is ~30% higher than Tehran; the produced water from systems collected in transparent plastic bottle and expose under sunlight during 8 h of experiment to use the advantage of solar water disinfection (SODIS). Results showed that from energetic point of view, utilizing nanofluid has great impact on the systems while from exergetic viewpoint the altitude has the greatest impact on the systems. The highest instantaneous energy and exergy efficiency was obtained by Tochal-located loaded with nanofluid by 55.98% and 9.27% respectively. Also, overall energy and exergy efficiency of Tochal-located system loaded with nanofluid compared to Tehran-located without nanofluid improved by about 106% and 196% respectively. Finally, using silver nanoparticle for double-purposes (anti-bacterial and enhancing heat/mass transfer) and exposure the distilled water under sunlight for SODIS can results to produce healthier water.