EXPERIMENTAL INVESTIGATION ON HEAT TRANSFER ENHANCEMENT WITH LOOSE-FIT PERFORATED TWISTED TAPES


Güneş S. , Karakaya E.

HEAT TRANSFER RESEARCH, vol.50, no.9, pp.821-837, 2019 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 50 Issue: 9
  • Publication Date: 2019
  • Doi Number: 10.1615/heattransres.2018027756
  • Title of Journal : HEAT TRANSFER RESEARCH
  • Page Numbers: pp.821-837

Abstract

The thermal and flow resistance characteristics in a tube equipped with loose-fit perforated twisted tapes (LPTTs) were examined experimentally under uniform heat flux conditions. Two different twisted tape widths (W = 52 mm and 54 mm), which are smaller than the tube inside diameter of 56 mm, were taken into account with the purpose of minimizing the excessive friction loss related to the full width twisted tape elements. The experimental work was carried out with two different twisted tape width ratios (W/D = 0.9285 and 0.9642) and three different twist ratios (y/D = 2.0, 2.5, and 3.0) at a constant hole diameter ratio d/D = 0.0714, in a range of Reynolds numbers from 4859 to 24,000. The experimental results showed that the Nusselt number (Nu) and friction factor (f) increase with increasing W/D and decreasing y/D. A maximum value of the thermal performance factor (TPF) of 1.35 was provided by the use of a twisted tape with W/D = 0.9642, and y/D = 2.0 at Re = 5200. Consequently, correlations of Nu, f, and HT for all investigated cases were also proposed.