The effects of winglet twisted tapes on heat transfer in turbulent flow pipes

In this study, effect of twisted tape elements that were located throughout the test pipe with rectangular fins on heat transfer and flow characteristics for 4000-20000 Reynolds number interval was investigated experimentally, with turbulent flow in pipe. All the experiments were conducted under forced convection and constant heat flux boundary conditions. Tests were repeated for 9 different finned twisted, i.e., three different fin widths (1.5, 3 and 5 mm) and three different fin angles (β=5°, 10° and 15°) and typical twisted tape elements. The data from the experimental measurements; Nusselt number (Nu) and friction factor (f) changing according to the Reynolds number (Re) were evaluated by means of empirical correlations and tables. According to the obtained results, it is seen that twisted tape elements with rectangular fins increase both the Nusselt number and the friction factor comparing to the typical twisted tape. As a conclusion, the highest thermal performance result is obtained by means of the rectangular finned twisted tape element that has β=5° fin angle and 1.5 mm fin width, according to the comparison between plain pipe, typical twisted tape inserted pipe, and rectangular finned twisted tape inserted pipe.