Comparison of hydrodynamic, energy and exergy efficiency of two-phase hybrid nanofluid in parabolic trough solar collector with vortex generator and turbulator

Abstract

The present study follows a 3D modeling of the geometry of a parabolic trough solar collector (PTSC) equipped with a twisted cross turbulator (TCT) and a Vortex Generator with Pitch Ratio (VGPR), considering the finite volume method (FVM) to solve the governing equations. The absorber tube (AT) of this PTSC is equipped with a TCT and a VGPR in order to increase thermal performance (TP). Also, the efficiency of their use on different output parameters have been compared. In addition, in order to be more practical, the efficiency of the geometric shape of the TCT and VGPR on various parameters in the output has been investigated. In order to make the study more practical, graphene oxide (GO) and double-walled carbon nanotubes (DWCNT) nanoparticles (NP) are dispersed in the base fluid (BF). The study is conducted at high Reynolds numbers (Re) (from 15,000 to 60,000), corresponding to the turbulent regime's range. Numerical simulation results show that the velocity change in the AT is a positive factor in all cases of increase. Because in all these cases, the increase of this parameter has caused the average Nusselt number (〖Nu〗_ave) to rise. Also, Syltherm 800 (BF) has a lower thermal conductivity (k) coefficient than hybrid nanofluid (HNF) Syltherm 800/DWCNT- GO, resulting in lower TP in PTSC. The addition of TCT, VGPR, and their geometrical change has a positive role in the hydrodynamic behavior of Syltherm 800/DWCNT-GO HNF flow. In all geometric modes, the PEC index are more significant than one, so using these two mechanical parts always has a better TP than the pressure drop (P) resulting from their presence. Finally, by examining the exergy efficiency (_ex), It was observed that the maximum practical work received from the solar system (SS) was obtained when using the VGPR in the flow path of HNF Syltherm 800/DWCNT-GO.