Oflaz Y., Ogunc Y., Dalkılıç A. S.
Scientific works/Elmi eserler, cilt.1, sa.1, ss.1-10, 2026 (Düzenli olarak gerçekleştirilen hakemli kongrenin bildiri kitabı)
Özet
> **Abstract**
> This study investigates the thermal-hydraulic performance of a 0.45 m counter-flow double-pipe heat exchanger operating under turbulent flow conditions using theoretical correlations and Computational Fluid Dynamics (CFD) simulations. Hot water flowing through the inner tube at a mass flow rate of 0.125 kg/s and an inlet temperature of 355 K, and cold water flowing through the annular section at 0.215 kg/s and 305 K, are considered as working fluids. The heat transfer characteristics and outlet temperatures are evaluated using the ε-NTU method, with the Petukhov–Kirillov and Gnielinski correlations applied for the inner tube and annulus regions, respectively. The theoretical results are validated against CFD simulations performed using commercial software. The comparison shows a deviation of 0.13% for the cold-water outlet temperature and 0.69% for the hot-water outlet temperature relative to the CFD results. These findings demonstrate that the selected empirical correlations provide accurate and reliable predictions under the investigated operating conditions and confirm the effectiveness of the developed thermal-hydraulic model for heat exchanger analysis.