Performance assessment of turbular heat exchanger tubes containing rectangular-cut twisted tapes with alternate axes

This paper describes the numerical results of the heat transfer enhancement mechanism of tubes containing rectangular-cut twisted tapes with alternate axes (ARC-TTs). Influence of the length of cut ratio (LR = L/w = 2.0, 2.4 and 2.8) and width of cut ratio (WR = W/w = 0.7, 0.8 and 0.9) on the heat transfer rate, friction factor and thermal performance characteristics are presented. The contour plots of predicted streamlines, velocity field, temperature field, and local Nusselt number distribution are also given for a better understanding of heat transfer mechanism. The results of the tube containing a classical twisted tape are also reported, for comparison. It can be observed that the use of ARC-TTs results in more disordered streamlines and higher turbulent intensity than that of the classical twisted tape. The numerical results also show that heat transfer and friction loss decrease as Length of cut ratio (LR) and Width of cut ratio (WR) increase while thermal performance factor shows reverse trend. In the studied range, utilizing ARC-TTs offers thermal performance factor up to 1.5.