This paper presents three dimensional numerical simulations of parabolic trough collectors (PTC) based on two low-Reynolds eddy viscosity turbulence models, namely; Launder and Sharma k-epsilon and k-omega SST models. For the simulations, water was used as the Heat Transfer Fluid (HTF) with four different nanoparticles; Al2O3, TiO2, CuO and Cu. Different volume fractions () of the nanoparticles were investigated for various Reynolds (Re) numbers with uniform
heat flux. Results showed that the overall performance of the system is more sensitive to changes in the thermal properties of nanofluid than the thermal properties of the HTF. At a volume fraction of 6% and a Re number of 70,000, the Nusselt number (Nu) enhancement of nanofluids TiO2-water, Al2O3-water, CuOwater and Cu-water were found to be 21.5%, 20.2%, 18.11% and 15.7% respectively while the performance evaluation criteria (PEC) were 1.214, 1.2, 1.18 and 1.155 respectively.