Investigation of the effects of wavy twisted tapes on heat transfer and friction factor in turbulent flows pipe

In this study, the effects of wavy twisted tapes placed on the center of the pipe in the turbulent flows in the pipe, and the effects of Reynolds number 4892-21480 on heat transfer and pressure losses were investigated experimentally. The positive and negative effects of the surface formed by the wavy twisted tapes and the turbulence formed by this surface have been observed. The data obtained from the experimental study; Changes of Nusselt Number (Nu) and friction coefficient (f) due to Reynolds Number (Re) were interpreted using empirical relations and tables. The experiments were repeated for 2 different amplitudes of D/4, D/8 and 3 different wave numbers of wavy twisted tapes with D/2, 3D/4 width and 4D, 6D twisted ratios. As a result, the increase in heat transfer, pressure drop and net recovery were determined for 24 different tapes. As the results of experiments conducted by used of total 24 tapes, the highest net heat transfer improvement rate has been seen as rate of 1.31 in the tape of B9 (E=D/2, S=6D, a=D/4, z=3) at Re = 5148 value. Keywords: Friction coefficient, heat transfer enhancement, in-pipe turbulent flow, wavy twisted tape