Effect of nanofluid properties and mass-flow rate on heat transfer of parabolic-trough concentrating solar system

Sustainable power generation, energy security, and global warming are big challenges to the world today. The issues may be addressed through the use of renewable energy resources, among them, concentrated solar energy. The performance of a parabolic-trough collectors receiver is here investigated analytically through water and therminol-VP1-based CuO, ZnO, Al2O3, TiO2, Cu, Al, and SiC nanofluids. Increased volumetric concentrations of nanoparticle is found to enhance heat transfer, with heat transfer coefficient the maximum in W-Cu and VP1-SiC, the minimum in W-TiO2 and VP1-ZnO at 0.8 kg/s flow rate. Changing mass flow rate also affects heat transfer coefficient, which increases to the maxima of 23.30% in W-SiC and 23.51% in VP1-SiC when mass-flow rate increased in laminar flow. Heat transfer enhancement drops in the period when laminar flow transitions into turbulent flow. The maximum heat transfer enhancements by W-Cu and VP1-SiC nanofluids during turbulent flow were found to be 9.49% and 10.14%, respectively. The heat transfer enhancements of nanofluids seem to remain constant when compared with base fluids, during either laminar flow or turbulent flow (because in base fluids and nanofluids, heat transfer enhances at the same rate as mass flow rate increases)