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

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

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
Volume54
Issue number15-16
DOIs
Publication statusPublished - 2011 Jul 1

Fingerprint

pressure drop
Pressure drop
Nusselt number
heat transfer
Heat transfer
augmentation
Graphic methods
centrifugal force
ducts
Ducts
Reynolds number
Vortex flow
vortices
tubes
Infrared radiation
coefficients
Hot Temperature

All Science Journal Classification (ASJC) codes

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

Cite this

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abstract = "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.",
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Heat transfer and pressure drop in a square spiral channel roughened by in-line skew ribs. / Chang, S. W.; Chiang, K. F.; Kao, J. K.

In: International Journal of Heat and Mass Transfer, Vol. 54, No. 15-16, 01.07.2011, p. 3167-3178.

Research output: Contribution to journalArticle

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