Fin angle effect on heat transfer enhancement in double-tube heat exchangers
Engineering Science and Technology, an International Journal, cilt.81, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 81
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.jestch.2026.102481
- Dergi Adı: Engineering Science and Technology, an International Journal
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, INSPEC, Directory of Open Access Journals
- Anahtar Kelimeler: Fe3O4 nanoparticles, Fin angles, Heat transfer enhancement, Liquid-air heat exchanger, Nano-fluid, Thermal performance factor
- Gazi Üniversitesi Adresli: Evet
Özet
This study aims to experimentally investigate the effect of combining Fe3O4–water nano-fluid and longitudinal fins with different inclination angles on the thermal and hydraulic performance of a double-tube heat exchanger. The experimental system consists of 30 fins arranged in an annular configuration on a horizontally positioned inner tube. The fins are placed at inclination angles of 90°, 60°, 45°, and 30°, with 14 plate-type fins of 30 mm height in each ring. The study was conducted at inlet temperatures of 313.15 K and 323.15 K and flow rates ranging from 0.2–2 L/min (Re = 249–3000). Air was used as the external fluid at a constant flow rate of 1250 L/min. The nano-fluid was prepared to contain 0.5% by volume of Fe3O4 nanoparticles. In the performance evaluation, the heat transfer coefficient, Nusselt number, friction factor, and thermal performance factor (TPF) were considered. The results show that the use of nano-fluid and fins significantly increases heat transfer compared to a smooth tube. Among all tested configurations, the 90° fin orientation yielded the highest performance improvement, followed sequentially by the 60°, 45°, and 30° arrangements. In conclusion, for temperatures of 313.15 K and 323.15 K, the overall heat transfer coefficient and Nusselt number increased by 246.26–250.94% and 233.55–253.91%, respectively, while the friction factor increased by 1.080–1.094. At an inlet temperature of 313.15 K, the thermal performance factor (TPF) values for the double-tube heat exchanger were calculated as 1.97, 3.147, and 3.376 for 0.2, 1, and 2 L/min, respectively, while at 323.15 K, the TPF values were calculated as 2.27, 3.19, and 3.25. These findings demonstrate that the combined use of nano-fluid and optimised fin geometry is an effective method for designing compact and highly efficient heat exchangers.