Developing heat transfer and friction in a ribbed rectangular duct with flow separation at inlet

Journal Article · Sat Aug 01 04:00:00 EDT 1992 · Journal of Heat Transfer (Transactions of the ASME (American Society of Mechanical Engineers), Series C); (United States)

DOI:https://doi.org/10.1115/1.2911319· OSTI ID:7016220

Liou, Tongmiin; Hwang, Jennjiang ^[1]

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1. National Tsing Hua Univ., Hsinchu (Taiwan)

The local heat transfer and pressure drop characteristics of developing turbulent flows in a rectangular duct with an abrupt-contraction entrance and repeated square-rib pairs on the two opposite walls have been investigated experimentally. Both entrance-region and periodic-fully-developed-region results were obtained. Laser holographic interferometry was employed in the local and average heat transfer measurements. The Reynolds number was varied from 5.0x10[sup 3] to 5.0x10[sup 4]; the rib pitch-to-height ratios were 10, 15, and 20; and the rib height-to-duct height ratio was kept at a value of 0.13. The results allowed the entry length to be determined and the regions susceptible to hot spots to be located. Semi-empirical heat transfer and friction correlations for the periodic fully developed region were developed. Moreover, performance comparisons between the ribbed and smooth ducts were made under two types of constraint, namely equal mass flow rate and equal pumping power. Finally, the effect of thermal entry length on the length mean Nusselt number was also investigated. The results showed that the length mean Nusselt number ratio was a function of only the duct length and independent of PR and Re, and could be further correlated by an equation of the form [bar N]u[sub m]/[bar N]u[sub p]=1 + 1.844/(X/De).

• OSTI ID: 7016220
• Journal Information: Journal of Heat Transfer (Transactions of the ASME (American Society of Mechanical Engineers), Series C); (United States), Journal Name: Journal of Heat Transfer (Transactions of the ASME (American Society of Mechanical Engineers), Series C); (United States) Vol. 114:3; ISSN JHTRAO; ISSN 0022-1481
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420400* -- Engineering-- Heat Transfer & Fluid Flow
DUCTS
ENERGY TRANSFER
FRICTION FACTOR
HEAT TRANSFER
HOLOGRAPHY
INTERFEROMETRY
LASERS
NUSSELT NUMBER
PERFORMANCE TESTING
PRESSURE DROP
REYNOLDS NUMBER
TESTING