The use of energy in an eficcient way has been an important topic by the increasing energy demand. In this study, the efficiency of the heat exchangers used commonly in lots of fields in industry has been subjected. In concentric circular heat exchanger, distilled water and water based Al₂O₃ nanofluids with 0.4% and 0.8% volumetric concentrations have been used as working fluid. Used nanofluids have been prepared in the laboratory conditions, and thermal conductivity and viscosity measurements have been made, these values have also been used in the calculations. In the light of obtained data, Al₂O₃-water nanofluid with 0.4% volumetric concentration provided 14.5% enhancement, while Al₂O₃-water nanofluid with 0.8% volumetric concentration provided 19% enhancement. Furthermore, it was concluded that nanofluids did not cause significant increase in pressure drop.