Thermal-hydraulic performance of a solar collector with twisted vortex generators and hybrid nanofluid: A simulation by numerical method and two-phase model

Abstract

In this study, a solar collector (SC) assembled with a twisted vortex generator (TVG) filled with DWCNT-SiO2/water hybrid nanofluid (HNF) is simulated using computational fluid dynamics (CFD). Numerical simulation is employed for analysing the SC and HNF is simulated using the mixture model two-phase (TP). Standard k-ε turbulence model is used to model the turbulent flow. The inlet Reynolds number (Re) changes from 8000 to 32,000, the volume fraction (φ) of silicon oxide nanoparticles (NPs) and DWCNT varies from 2 to 6%, and the pitch ratio (β) of the TVG is 0.25, 0.50, 0.75, and 1. The results demonstrate that the average Nusselt number (Nuave) is enhanced with Re and φ. When φ = 6% and Re = 32,000, adding a TVG with a β of 1 inside the SC leads to an improvements in the Nuave by 78.23% in comparison to the SC without a TVG. In addition, the pressure drop (ΔP) increases with Re and φ. When φ = 4% and Re = 32,000, adding a TVG with a β of 1 inside the SC results in an increment in the Δp by 329.76% in comparison to the SC without a TVG. Finally, the results of the thermo-hydraulic performance (PEC) reveal that the use of a TVG is desirable when 8000 < Re < 32,000 and 2% < φ < 6%.