Numerical analysis of the nanofluid flow characteristics of perforated conical rings in a heat exchanger tube has been investigated under constant wall temperature condition. The pitch ratio of the perforated conical rings is 4 and the number of holes is varied from 0 (typical conical ring) to 10. The flow regime is fully turbulent with the Reynolds number is varied from 5000 to 14,000 and Cu-water nanofluid (0 < phi< 1.5%) is selected as the working fluid. The main novelty of this paper is to perform a 3D simulation of this problem because some previous studies using similar geometry were restricted to experimental analysis. The Reynolds averaged Navier Stokes (RANS) equations are solved with the finite volume method using (RNG) k - c model. A significant heat transfer enhancement is obtained by using compound perforated conical rings and nanofluids. The heat transfer enhancement provided by PCR with N = 4 is 278.2% higher than plain tube. The maximum thermal performance of 1.10 is obtained by using Cu-water nanofluid with phi= 1.5% and perforated conical rings with N = 10 at Re = 5000. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.