Hybridization of rotary absorber tube and magnetic field inducer with nanofluid for performance enhancement of parabolic trough solar collector

Abstract

A considerable amount of energy is lost in the parabolic trough solar collectors due to the poor capability of working fluid in full absorption of the concentrated solar irradiation across the receiver tube. A new hybrid method is recommended here to cover up such deficiency by simultaneously using a rotary absorber tube and magnetic field inducer with nanofluid. Results showed that the combination effects of the receiver rotation and the magnetic field improve the convection mechanism in the absorber and increase both energetic and exergetic performance of the collector. The study reveals that there is an optimal rotational speed in the each magnetic field intensity for different hydrothermal and thermodynamic parameters. That is, in comparison with the case with no magnetic field and rotational tube employment, the total heat loss in the collector can be saved by 37.4% when a magnetic field of 1000 G and a rotary tube with speed of 0.4 rad/s are employed simultaneously. In this comparison, a maximum improvement of 101% and 24% in the performance evaluation criteria (PEC) and exergy efficiency of the system is achieved by employing the proposed hybrid method, respectively. Results also revealed that there is an optimal rotational speed in the each magnetic field intensity, in which employing a magnetic field at this rotational speed does not increase pressure drop for the sake of improving energetic and exergetic efficiencies of the solar collector.