In the present study, performance analysis of a shell-and-double concentric tube heat exchanger (SDCTHEX) is carried out using commercially available CFD software ANSYS FLUENT 14.0. First, the SDCTHEX having fixed inner tube diameter is compared with classical shell-and-tube heat exchanger (STHEX) for their thermo-hydraulic performances for different mass flow rates of the hot fluid. Then, the effects of different inner tube diameters on the performance of SDCTHEX are investigated. The results show that the average percentage increase in overall heat transfer rate per overall pressure drop of SDCTHEX with inner tube diameter equal to 8/12 mm/mm, is nearly 343% higher than that of STHEX while the total friction power expenditure of SDCTHEX is reduced by around 85.5% as compared to that of STHEX. Also the overall heat transfer rate per overall pressure drop of SDCTHEX is sensitive to inner tube diameter. It is found that Phi/Delta P for the mass flow rate of 22.5 kg/s is maximum and found to be about 400% higher at inner tube diameter of 12/16 mm/mm with respect to the STHEX. The results of simulation present that, the SDCTHEX has a higher heat transfer performance while maintaining a lower pressure drop. It is also found that higher effectiveness may be achieved at lower inner tube diameters as well with higher hot fluid mass flow rates which would be economical. This suggests that the SDCTHEX might be ideal choice to replace the classical STHEX in heat exchanger industrial applications (C) 2016 Elsevier Ltd. All rights reserved.