Heat transfer enhancement of a copper tube with constant wall temperature using a novel horizontal perforated teardrop-shaped turbulators (PTST)

Considering that turbulators generally have a high pressure drop level and as a result low thermal performance, in this research a numerical study conducted for a new form of aerodynamically designed turbulators that are concentrically perforated to have less pressure drop. In this study, the effects of a novel perforated teardrop-shaped turbulator (PTST) on the hydro-thermal parameters were numerically examined. Results were compared with a plain tube and a tube equipped with a simple teardrop-shaped turbulator (STST). PTST with the horizontal perforation geometry including a square, hexagon, octagon, and circle holes was installed inside a copper tube with constant wall temperature. The effect of the horizontal perforation cross-section area on the heat transfer and pressure drop was also evaluated. Tests were conducted under turbulence flow rates in the range of 0.044–0.099 kg/s. To select the optimal case, the thermal enhancement factor (TEF) was calculated. The results clarified that the hole area and hole geometry have a significant effect on TEF and hydro-thermal parameters. The highest heat transfers and pressure drop took place in the presence of the STST, while the highest TEF was equivalent to 1.39 and occurred in the presence of a PTST with a 5 mm diameter circular hole. The heat transfers in the presents of STST and PTST increased by 310.1% and 298% compared to the plain tube. Finally, a correlation expressing the relationship of TEF and perforation area was also presented based on curve fitting.