Improving the Thermo-fluid Performance of a Shell and Corrugated Coil Heat Exchanger with Novel configurations

Abstract

Abstract In the current investigation, novel coil configurations of a shell and corrugated coil heat exchanger (SCCHX) were experimentally examined and compared with the conventional smooth coil heat exchanger (SSCHX). The innovative coil design enhances the disruption of the thermal boundary layer by increasing the fluid mixing by the curved coil and the corrugation compared to conventional helical designs. This geometry promotes better fluid mixing near the coil surface, resulting in a more uniform temperature distribution, reduced temperature polarization, and a higher temperature difference between the coil and the surrounding fluid. The influence of coil configuration, inclination angle, and Reynolds number on the thermo-fluid performance was examined. Six curved coils were designed and fabricated for this investigation. Three smooth configurations-model A (divergent-convergent design), model B (convergent-divergent design), and model C (traditional helical design) as well as three corrugated configurations were tested. The experiments were conducted at inclination angles of 0°, 45°, and 90°. The experimental runs covered a range of Dean number, of 2000 ≤ Dni ≤ 12400, corresponding to mass flow rates, of 0.032 ≤ m˙i ≤ 0.18 kg/s on the coil side and 0.067 ≤ m˙sh ≤ 0.175 kg/s on the shell side. The new coil configurations showed significant enhancements in the Nusselt number (Nui) by 67.8% and 34.2% for the smooth configurations (models A and B) compared with model C, and by 65.7% and 30.2% for the corrugated configurations at an inclination angle of 90°. Conversely, the new coil configurations increased the friction factor (fi) by 26.7% and 50.4% for the smooth configurations (models A and B) compared with model C, and by 21.4% and 31.1% for the corrugated configurations at 90°. In addition, the inclination angle of 90° recorded the highest thermal performance among all inclination angles, albeit at the expense of higher pressure drop. The maximum thermal performance index (TPI), values of 2.75, 2.6, and 2.5 were obtained for models A, B, and C, respectively, at an inclination angle of 90°.