Thermohydraulics of turbulent flow through a round tube by a peripherally-cut twisted tape with an alternate axis

The effect of peripherally-cut twisted tape with alternate axis (PT-A) on the fluid flow and heat transfer enhancement characteristic in a uniform heat flux circular tube has been experimentally investigated. Experiments were conducted using water as a testing fluid in a turbulent tube where the Reynolds number was varied from 5000 to 20,000. Peripherally-cut twisted tape (PT) and typical twisted tape (TT) were also tested in similar conditions, for comparison. Evidently, the heat transfer rates in the tube fitted with the PT-A, PT and TT are respectively enhanced up to 184%, 102% and 57% of that in the plain tube. In the present Reynolds number range tested, the PT-A, PT and TT offer the maximum thermal performances at constant pumping power of 1.25, 1.11 and 1.02, respectively. In addition, the correlations of the Nusselt number, friction factor and thermal performance were developed for the tube equipped with the PT-A in terms of peripherally-cut tape width ratio (w/W), Reynolds number (Re) and Prandtl number (Pr).