Effects of serrated circular ring with rectangular winglets on thermal properties of tube heat exchanger: an experimental and numerical study.

The influence of serrated circular rings with rectangular winglets (SCRWRW) on the thermal performance of circular tube heat exchanger has been studied experimentally and computationally. The geometrical parameters considered are diameter ratio (DR = 0.8, 0.85), pitch ratio (PR = 3, 4), attack angle (ϴ = 15°, 30°, 45°), and blockage ratio (0.05). The test section is a circular tube of length 1.5 m and diameter 68.1 mm, in which uniform heat flux of 1000 W/m2 has been applied. Air is the working fluid flowing in the range of Reynolds number between 6000 and 24000. The results obtained showed that SCRWRW enhances heat transfer rate 5.54 times of smooth tube while the maximum thermal performance obtained is 3.2 at DR = 0.85, PR = 3, and ϴ = 15°. The computational investigation has also been carried out using Ansys fluent and presented the effect of SCRWRW on temperature distribution and fluid flow. SCR: Serrated Circular Ring; SCRWRW: Serrated Circular Ring with Rectangular Winglets; DR: Diameter Ratio (d/D); PR: Pitch Ratio (l/D); BR: Blockage Ratio (H/D) [ABSTRACT FROM AUTHOR]