Energy, exergy, economic and environmental analysis of parabolic trough collector containing hybrid nanofluid equipped with turbulator

Abstract

This study aims to examine the effects of twisted tape (TT) turbulators and compound TT turbulators in parabolic trough collector (PTC) in relation to energy, energy efficiency, economic efficiency, and environmental efficiency. The PTC contains a two-phase CuO-SWCNT/Water hybrid nanofluid (HNF). The study has been carried out with the assumption of turbulent flow, the Reynolds number (Re) range of 12,000 to 18,000, and a volume fraction (ϕ) of 2 to 6% of nanoparticles (NPs). A hexagonal spring coil was used in the riser tube as a turbulator, while the TT placed inside the hexagonal spring coil was used to create a continuous rotating flow alongside the tube's wall. Based on the results, the values obtained from the average Nusselt number (Nuave) and the friction coefficient enhance when using the turbulator. In addition, the thermal performance of the PTC when using a two-phase CuO-SWCNT/Water HNF is far more favorable than water base fluid. The heat transfer rate in the PTC with turbulator is enhance between 20 and 60%. These results indicate better performance and reduction of the heat loss of PTC with turbulator within the absorbent tubes rather than the typical type. Also, by increasing the flow velocity and ϕ of NPs, the Levelized Cost of Energy (LCOE) value can be reduced. Therefore, LCOE changes are primarily caused by changes in thermal efficiency. The amount of environmental pollutants created for the PTC operation with nanofluid is less than the base fluid. The thermal performance of the PTC with compound TT and wired coil (Case C) at Re = 18,000 and φ=2% is about 3.58 percent higher than the PTC with TT (Case A). Also, the performance evaluation criterion for Case A is about 20% higher than that for Sample C. Moreover, the exergy efficiency of the fluid containing nanoparticles with a volume fraction of 2% has decreased by approximately 31.7% and 32.2% with increasing velocity for samples A and C, respectively.