In this study, turbulent flow characteristics of CuO-water nanofluid through heat exchanger pipe enhanced with louvered strips are numerically investigated. Nanoparticles volume fraction (phi) varied from 0 to 2%. The louvered strips are mounted in single and double geometries. The slant angle (theta) and the Reynolds number (Re) are within 15 degrees - 25 degrees and between 5000 and 14,000, respectively. (RNG) k - epsilon model is employed based on the finite volume technique. The results illustrated that strong flow disturbance between the wall and the louvered strip is the main reason for turbulent kinetic energy increment. Besides, the nanoparticles improve the thermophysical properties of the working fluid, which results in better heat transfer. The Nu number increases 15.6% by using nanofluid instead of water at Re = 14000. The highest thermal enhancement parameter of 1.99 is obtained at Re = 14000 by using double perforated louvered strip with theta = 25 degrees. The recirculating flow inside the holes can significantly improve the thermal performance. (C) 2020 Elsevier B.V. All rights reserved.