Heat transfer and pressure drop in a square spiral channel roughened by in-line skew ribs

S. W. Chang, K. F. Chiang, J. K. Kao

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11 Citations (Scopus)


This experimental study examines the detailed Nusselt number (Nu) distributions, pressure drop coefficients (f) and thermal performance factors (TPF) for a square spiral channel with two opposite endwalls roughened by in-line 45° ribs. Detailed Nu distributions over the rib floor with forward and backward flows are measured using the steady-state infrared thermo-graphic method at Reynolds numbers (Re) of 900-30,000. With the increased f from the smooth-walled straight tube references (f), the rib-induced sectional vortical flows interact with the centrifugal-force driven Dean vortices along the entire spiral passage to generate the considerable heat transfer enhancement (HTE) impacts that raise the area-averaged turbulent Nusselt numbers (Nu) to 8.41-3.66 and 5.05-2.78 times of the Dittus-Boelter Nusselt numbers (Nu) for forward and backward flows at 2700 ≤ Re ≤ 30,000, respectively. Comparisons of Nu/Nu∞,f/ f∞ and TPF obtained from the ribbed spiral channel with other types of HTE devices reveal the thermal performances of the present HTE measure. Two sets of Nu and f correlations for the square spiral ribbed duct with forward and backward flows are generated to assist the design applications using this HTE measure.

Original languageEnglish
Pages (from-to)3167-3178
Number of pages12
JournalInternational Journal of Heat and Mass Transfer
Issue number15-16
Publication statusPublished - 2011 Jul 1

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes


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