Enhancing parabolic trough collector thermal efficiency: Experimental investigation of hybrid nanofluid

Abstract This study examines the performance of parabolic trough collectors (PTCs) in series with a hybrid nanofluid consisting of multi-walled carbon nanotubes (MWCNT) and cobalt (III) oxide nanoparticle (Co 2 O 3 ). In this study, distilled water sourced from Amman, Jordan, was used as the working fluid, while gum arabic served as the surfactant. Initially, the flow rate was 1 L min −1 , and water was used as a thermal medium to join two identical PTC devices in a sequence. Subsequently, a hybrid-type nanofluid with different volume concentrations was used for experiments namely; 0.01%, 0.04%, and 0.1%. All tests were conducted between 10 a.m. and 2 p.m. on different days, equipping both collectors with a digital tracking system. After the nanofluid was prepared and tested, the heat-handling performance of the PTCs was evaluated at different concentrations of MWCNT and Co₂O₃, and the results were compared to those of pure water. In the tests, the best thermal efficiency (17.84%) was achieved when the hybrid nanofluid was used at a concentration of 0.1%. The MWCNT and Co 2 O 3 nanofluids with concentrations of 0.04% and 0.01% obtained thermal efficiency of 17.6% and 17.02%, respectively, while water obtained 15.07%. By increasing the concentration to 0.1%, a peak optical thermal efficiency of 18.38% was achieved.