3D Numerical Study of Conical and Fusiform Turbulators for Heat Transfer Improvement in a Double-Pipe Heat Exchanger

Abstract This study demonstrated the effect of conical and fusiform turbulators placed in double-pipe heat exchanger (DPHE) on the heat transportation and turbulent flow designs. A total of 21 configurations including conical and fusiform turbulator inserts are simulated in a double-pipe heat exchanger with circular and rectangular tube configurations at four Reynolds number levels (Re = 4000, 7000, 10000, and 13000) on the tube side. Utilizing Fluent software, the finite-volume scheme is implemented to discretize the turbulence flow equations using the realizable k–e model. The results demonstrate that the maximum convective heat transfer coefficient is achieved when using a heat exchanger having a circular inner pipe. Further, the performance index of the heat exchanger (HE) is found to increase by modifying the shape of conical turbulators to fusiform. The DPHE with circular inner pipes and 12 mm fusiform turbulators is found to be the optimal configuration in-terms of thermal performance. At Re = 4000, the configuration with fusiform 9 mm inserts and a rectangular inner pipe with a 0.72 aspect ratio offered the highest coefficient of performance (approximately 27.74) with the overall heat transfer coefficient increased by 4.58% compared to the plain rectangular tube and by 4.68% compared to the circular tube without turbulators.