Numerical simulation study of flow and heat transfer characteristics of the spiral ribbed tube with elliptical dimples

In this study, a new type of spiral rib-reinforced heat transfer tube with elliptical dimples (referred to as SRTED) is proposed. Numerical simulations were performed to investigate the effect of different geometric parameters on the flow and heat transfer characteristics. The field synergy theory was adopted to reveal the enhanced heat transfer mechanism. The results demonstrated that the flow velocity reaches the maximum at the smallest cross-sectional area in the tube; besides, it tends to decrease with the increase of the cross-sectional area in the tube. The distribution trend of the local heat transfer coefficient (h) of SRTED has a periodic pattern; the average value is 1.41 times that of the plain tube and 1.13 times that of the dimpled tube. In the calculated Re range, the Nu/Nu0 of SRTED varies from 2.84 to 4.46, and f/f0 varies from 8.98 to 23.51. The overall thermal performance evaluation criterion (PEC) value varies from 1.18 to 1.78, with higher PEC at low flow rates.