Numerical study on enhanced heat transfer and friction factor characteristics of helical bead-groove tube

Abstract

The comprehensive thermo-hydraulic performance of a helical tube (HT) is improved in this study by proposing a new type of helical bead-groove tube (HBGT). The heat transfer performance and friction factor of HBGT, helical groove tube, and HT under the same conditions were compared by the numerical simulation method. The effects of different bead-groove positions, bead-groove density ratios, and depth ratios on the HBGT heat transfer and friction factor properties are analyzed. The research introduced the field synergy theory to investigate the enhanced heat transfer mechanism. The results show that the HBGT can strengthen the vortex and secondary flow intensity. Meanwhile, this structure can also reduce the average field synergy angle. Its performance evaluation criterion is increased by a maximum of 8.5% and 28.2% compared to the HBGT and the HT, respectively. Compared with the bead-groove position, the bead-groove density ratio and depth ratio have more significantly influenced the thermal performance of the HBGT. The Nusselt (Nu) and friction factor (f) correlations were calculated from simulation data with error limits of ±5% and ±10%, respectively, to forecast the Nusselt (Nu) and friction factor (f).