This work represents the results of optimization in a convective heat transfer and pressure drop of water flow in the annulus-side of horizontal double pipe heat exchangers. Therefore, the objective of this article is the application of differential evolution algorithm (DE) to solve mono-objective problems considering five cases with/without Single Segmental Perforated Baffles (SSPBs), which are fabricated with different holes spacing, void, cut and pitch ratios, which depends of the space between the holes (S-[3;6]), the diameter of the holes (í µí±‘ ℎ − [ 1; 4]) and the dimension of cut region (H-[3.35;10.05]). To be a successful heat transfer enhancement tool, the rise in convective heat transfer given due to existing perforated baffles in heat exchangers should be higher than the rise in the fluid pressure drop at same pumping power. The objective function is maximize the thermal performance index (TPI), which is determined using Nusselt ratio and friction ratios that are calculated using the values obtained for existing perforated baffles and no baffles. The results revealed that numerical study is capable to increase the efficiency of the heat exchanger. Eleven cases were studied with an improvement in efficiency. CFD analysis showed the accuracy of the DE approach to optimize the heat exchanger performance.