Energy and exergy investigation of alumina/oil and silica/oil nanofluids in hemispherical cavity receiver: Experimental Study

The objective of this work is the investigation of two oil-based nanofluids in a hemispherical cavity receiver of a solar dish concentrator. The investigated nanofluids are Alumina/oil and Silica/oil, while the used oil is the Behran thermal oil. The two nanofluids are examined experimentally and they are energetically and exergetically compared in order to determine their performance in the solar system. Thermal performance of the hemispherical cavity receiver was studied in the steady-state condition. The results elucidated that the average cavity thermal performance has improved with the application of Alumina/oil nanofluid compared to the application of Silica/oil nanofluid, and pure oil as the solar heat transfer fluid. It was found the lower heat loss coefficient of the hemispherical cavity receiver could be achieved using the Alumina/oil nanofluid than the Silica/oil nanofluid and pure oil as the solar working fluids. Three models were presented for cavity thermal performance versus the parameter Tin−TambIbeam using investigated nanofluids, and base fluid. Exergy efficiency and overall thermal efficiency of the hemispherical cavity receiver was highest using Alumina/oil nanofluid than two other investigated heat transfer fluids. Finally, it was concluded that hemispherical cavity receiver with Alumina/oil nanofluid is the best selection from the energy and exergy viewpoint.