CFD Analysis of the Effects of Fin Geometry and Fluid Velocity on the Performance of a Double-Pipe Heat Exchanger

Double-pipe heat exchangers are widely used in thermal systems, where improving heat transfer while controlling pressure losses is an important design consideration. The present study investigates the thermal and hydraulic performance of a double-pipe heat exchanger equipped with twisted-fin inserts. The objective was to examine the influence of fin geometry and hot- and cold-fluid velocity variation on heat-transfer performance. Three-dimensional CFD simulations were performed using CATIA V5 for geometry development and ANSYS Fluent 2023 for numerical analysis, with distilled water as the working fluid. The performance was evaluated using outlet temperature, pressure drop, friction factor, heat-transfer rate, convective heat-transfer coefficient, and Nusselt number. Among the investigated fin geometries, Case 4 provided the most suitable geometry, while Case 4.1 produced the highest heat-transfer rate, convective heat-transfer coefficient, and Nusselt number, with values of 2191.85 W, 2207.95, and 84.02, respectively. Case 4.5 provided the highest outlet temperatures. The study demonstrates that twisted-fin geometry and flow conditions strongly influence heat-transfer performance. Future work can investigate nanofluids, alternative tube materials, and other fin geometries to further enhance performance.