Effects of using ferromagnetic hybrid nanofluid in an evacuated sweep-shape solar receiver

Abstract

In the current study, fluid flow and heat transfer characteristics of forced convection ferromagnetic hybrid nanofluid (Fe3O4/CNT/water) flow in a sweep-shape collector are studied numerically. The three-dimensional governing equations have been solved numerically in the solution domain using control volume approach employing SIMPLE algorithm. Studied Reynolds numbers are determined in turbulent range between 6000 and 8000. The optimization was carried out by comparison of different parameters to reach the optimal case with the maximum performance evaluation criteria index. Based on obtained results, it is concluded that the model with Reynolds number of 8000 has the maximum values of performance evaluation criteria indexes during all studied volume fractions which followed by Reynolds numbers 7500, 7000 and 6000, respectively. Also, the model with tube diameter of 8 mm has the maximum values of performance evaluation criteria index during all studied Reynolds numbers and is followed by cases with 4 mm and 12 mm tube diameters, respectively. Since based on all obtained results in this work using nanofluid at φCNT = 1.35% leads to more thermal–hydraulic performances than using nanofluid with φCNT = 0.10%, the sweep-shape collector with tube diameter of 8 mm filled with Fe3O4/CNT/water hybrid nanofluid with φCNT = 1.35% and φM (%) = 0.9% volume fraction and 30 nm nanoparticle diameter at Reynolds number of 8000 is presented as the best model in the current study.