The study investigates the effect of wire coil inserts on heat transfer enhancement and fluid flow characteristics in a double-pipe heat exchanger. Experiments were conducted with Reynolds numbers ranging from 5500 to 15000, and data were collected for fifteen different combinations of wire coil inserts, including five pitch ratios (P/Dc = 0.625, 1.25, 1.875, 2.5, and 3.125) and three wire diameters (d = 1, 1.5, and 2 mm). The results show that wire coil inserts significantly enhance heat transfer compared to traditional tubes. For the given Reynolds number range, the maximum heat transfer performance improvement was 126.7% at a pitch ratio of 0.625 and wire diameter of 2 mm, with friction factors 2.67–4.71 times higher than traditional tubes. The thermal performance factor (TPF) for all combinations was greater than unity, with the maximum TPF of 1.35 achieved at a pitch ratio of 0.625 and wire diameter of 2 mm. This indicates that wire coil inserts are an effective method for enhancing heat transfer in heat exchangers. The study highlights the advantages of passive techniques over active techniques in heat exchanger design, as passive methods are easier to fabricate and install, reducing costs. The use of wire coil inserts also enhances heat transfer by disturbing the fluid flow, disrupting the laminar sub-layer, creating boundary layer separation, and introducing additional flow. These inserts are also known as vortex generators, as they generate longitudinal vortices that increase heat transfer. The study also discusses various other types of inserts used for heat transfer augmentation, including twisted tape inserts, helical screw inserts, and louvred strip inserts. Overall, the study demonstrates that wire coil inserts are an effective method for enhancing heat transfer in heat exchangers.The study investigates the effect of wire coil inserts on heat transfer enhancement and fluid flow characteristics in a double-pipe heat exchanger. Experiments were conducted with Reynolds numbers ranging from 5500 to 15000, and data were collected for fifteen different combinations of wire coil inserts, including five pitch ratios (P/Dc = 0.625, 1.25, 1.875, 2.5, and 3.125) and three wire diameters (d = 1, 1.5, and 2 mm). The results show that wire coil inserts significantly enhance heat transfer compared to traditional tubes. For the given Reynolds number range, the maximum heat transfer performance improvement was 126.7% at a pitch ratio of 0.625 and wire diameter of 2 mm, with friction factors 2.67–4.71 times higher than traditional tubes. The thermal performance factor (TPF) for all combinations was greater than unity, with the maximum TPF of 1.35 achieved at a pitch ratio of 0.625 and wire diameter of 2 mm. This indicates that wire coil inserts are an effective method for enhancing heat transfer in heat exchangers. The study highlights the advantages of passive techniques over active techniques in heat exchanger design, as passive methods are easier to fabricate and install, reducing costs. The use of wire coil inserts also enhances heat transfer by disturbing the fluid flow, disrupting the laminar sub-layer, creating boundary layer separation, and introducing additional flow. These inserts are also known as vortex generators, as they generate longitudinal vortices that increase heat transfer. The study also discusses various other types of inserts used for heat transfer augmentation, including twisted tape inserts, helical screw inserts, and louvred strip inserts. Overall, the study demonstrates that wire coil inserts are an effective method for enhancing heat transfer in heat exchangers.