Heat transfer and pressure drop measurements for tubes fitted with twin and four twisted fins on rod

Shyy-Woei Chang, Wei Ling Cai, Ruo Sin Syu

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


Axial Nusselt number (Nu) distributions and tube averaged Fanning friction factors (f) for the tubular flows enhanced by twin or four twist-fin inserts with five twist ratios (y) of 2, 2.5, 3, 3.5 and ∞ (straight fins) were measured at Reynolds numbers (Re) of 750-70,000. For each enhanced tube with a twist-fin insert, the Nu and f augmentations from the plain-tube developed flow Nu and f references were compared with thermal performance factors (TPF) evaluated. Acting by the respective single- or twin-cellar axial swirls along the helical passages formulated by present twin or four twisted fins in the test tubes, the Nu/Nu ratios at laminar and turbulent reference conditions are respectively raised to 1.87-4.98 and 1.3-1.95; or 3.93-9.03 and 1.37-2.83. Relative to the Nu and f results measured from the test tubes enhanced by the two co-twisted tape inserts, present four twist-fin inserts considerably amplify both laminar and turbulent HTE ratios at the expenses of f augmentations with the laminar and turbulent TPF values in the respective ranges of 1.45-2.84 and 0.56-0.98. For assisting the relevant applications using present sets of Nu and f data generated by this study, the heat transfer and pressure drop correlations for the tubes with twin or four twist-fin inserts are devised.

Original languageEnglish
Pages (from-to)220-234
Number of pages15
JournalExperimental Thermal and Fluid Science
Publication statusPublished - 2016 Jun 1

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Nuclear Energy and Engineering
  • Aerospace Engineering
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes

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