Extensive Investigation of Hydrothermal Flow and Heat Performance Improvement in a 3D Tube Based on Varying Concavity Dimple and Corrugation Turbulator Configurations

Abstract

This study explored the influence of geometric parameters on corrugated tube heat exchangers under turbulent flow conditions. Eighteen different configurations were evaluated using both numerical simulations and experimental methods. The simulations, ranging from Reynolds numbers of 4000 to 15,000, analyzed various tube diameters, shapes, and disturbances. Results demonstrated that dimpled tube configurations significantly enhanced heat transfer compared with smooth tubes. The best performance, a pressure drop efficiency of 1.41 at a Reynolds number of 4000, was achieved with 2-mm dimples spaced 20 mm apart in an in-line pattern. Validation of the numerical results against experimental data demonstrated a high level of accuracy. The maximum deviation for the Nusselt number was 12% in smooth tubes and 15% in dimpled tubes. The maximum deviation for the friction factor was 6.1% in smooth tubes and 8.3% in dimpled tubes. The numerical model accurately represented the full dimensions of a commercial heat exchanger. Grid independence tests were conducted using a three-dimensional unstructured. To ensure accurate results, the study used a tetrahedral mesh and a Realizable k–ε turbulence model in its simulations. The findings revealed that corrugated tubes with various ring and dimple configurations dramatically enhanced heat transfer. Specifically, tubes with diameter rings, distance between rings, dimpled-ring diameters, and distance between dimple rings achieved maximum enhancements of 45.5%, 35.009%, 67.95%, and 58.42%, respectively. Furthermore, dimpled tubes with different diameters and distances also outperformed smooth tubes, showing heat transfer increases of 42% and 38.8%. The optimized dimpled tube design offers a promising approach for improving heat exchanger performance while minimizing pressure drop. Future research can build upon these findings to further refine and optimize corrugated tube heat exchanger technology.