Enhancement of thermo-hydraulic transport within a round tube using a twisted-staggered concave/convex dimples tape

Abstract

Purpose

The purpose of this study is to value the thermal and hydraulic transport augmentation of turbulent fluid flow within the round-pipe axis fixed by a twisted-staggered concave/convex dimples tape.

Design/methodology/approach

This study meets the report’s novel design by axis-inserting a twisted plastic tape with staggered concave/convex dimples of varying diameters (4 and 6 mm) and depths (1, 1.4 and 1.8 mm). Introducing a realizable model integrated with an improved wall function and SIMPLE solving procedure evaluates the thermo-hydraulic transport as Reynolds number is feasible as 5,000, 10,000, 15,000 and 20,000. In addition, using the findings from the present experimental work validates the numerical methodology.

Findings

This paper reveals that the staggered concave/convex dimples on the axis-fixed plastic tape can significantly improve thermo-hydraulic transport within this outer-heated tube. Furthermore, the processed dimples can cause flow disturbance, which increases turbulent kinetic energy and accelerates fluid mixing around a twisted plastic tape, resulting in enhanced thermal convection. The six kinds of twisted tapes (C1−C6) result in the thermo-hydraulic performance index (η) of 1.18–1.32 at Re = 5000. Among all the cases, the dimples using 4 mm combined with 6 mm diameter and 1.4 mm height (C4) earn the highest, around 1.40 at Re = 5,000.

Research limitations/implications

The conditions of constant hydraulic-thermal characteristics of working fluid (air), steady Newtonian fluid considered, and the ignored radiative heat transfer and gravity are the research limitations of the numerical simulation.

Practical implications

The given results can benefit from a round tube design of a thermal apparatus axis fixed by a twisted-staggered concave/convex dimples tape to augment the thermo-hydraulic transport.

Originality/value

Staggered concave/convex dimples on the surface of a twisted tape allow for impinging and swirling flow along the tape. These processed dimples can induce flow disturbance, which increases the turbulent kinetic energy and facilitates fluid mixing in a twisted tape. Furthermore, the hybrid-diameter dimples have enough flow channels for fluid separation-reattachment, and the thermo-hydraulic performance index has improved. This paper then presents a helpful passive approach for cooling a thermal device.