The current study presented numerical simulation for a double pipe heat exchanger (DPHE) with a counter-flow, in order to study the effects of twisting ratio for wavy edge twisted tape and the diameter of the holes it contains. The impact factors, varying Reynolds number (6957-187837), twisted tape ratio (0.5-3) on heat transfer and pressure drop. The inner tube, carrying hot air, incorporates twisted tapes to enhance turbulence and heat transfer. The outer tube, containing cold oil, experiences the effects of the enhanced flow But The Reynolds range is investigated range, and working fluids are on the side of the inner tube and annular space is hot air cold oil . Results demonstrate significant improvements in oil outlet temperature. Nusselt number (Nu) increases with increasing Reynolds numbers and twist ratios, the maximum Nu for enhancement devices with Tr = 0.5 and 3 are 38% and 10.7% higher than for the plain tube. Increasing Reynolds number and twisted tape ratio generally lead to higher heat transfer rates but also increased pressure drop. Optimal configurations of (Tr=2 and hole diameter 30mm)gave a best thermal performance index of 1.11 and 1.24 respectively when balancing heat transfer and pressure drop. The findings provide valuable insights for designing and optimizing heat exchangers in applications demanding efficient heat transfer.