Experimental study of carbon nano tube/oil nanofluid in dish concentrator using a cylindrical cavity receiver: Outdoor tests

The application of nanofluids is accounted as an effective way for improving the thermal performance of solar systems. In the current study, MWCNT/thermal oil nanofluid was experimentally tested as a solar heat transfer fluid. A dish collector, using a wounded cylindrical cavity receiver, was considered as the solar system. The main aim of this work was the experimental investigation of the cylindrical cavity's performance, using MWCNT/thermal oil nanofluid. Two experimental models were suggested for the prediction of the cavity's thermal efficiency, by considering MWCNT/thermal oil nanofluid and pure thermal oil in the steady-state period. It was indicated that the heat loss coefficient of the cylindrical cavity receiver decreased by the application of nano fluid. The results revealed the average thermal efficiencies of 63.9% and 56.44% for MWCNT/thermal oil nanofluid and pure thermal oil, respectively. The thermal efficiency was changed form 60.04% to 64.76%, by using the nanofluid, in the steady-state period. Also, it was observed that the thermal performance of the cavity receiver was improved by 13.12%, by using MWCNT/thermal oil nanofluid. Based on the obtained results, the application of MWCNT/oil nanofluid is recommended in the solar dish concentrators with cavity receiver.