Affiliation:
1. Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu, Taiwan 30043
Abstract
The effects of clearance ratio (C/H) and Reynolds number (Re) on the turbulent heat transfer and friction in a rectangular duct with ribs detached from one wall were characterized quantitatively using laser holographic interferometry and pressure measurements. The investigated flow was periodic in space both hydrodynamically and thermally. C/H and Re were varied from 0.25 to 1.5 and 5 × 103 to 5 × 104, respectively. The obtained interferograms, local (Nu) and average (Nu) Nusselt number, and thermal performance (Nup/Nus*) allowed the critical C/H characterizing different mechanisms of heat transfer augmentation to be identified and allowed a comparison of Nu, Nu, and Nup/Nus* among the detached ribbed duct, the attached ribbed duct, and the smooth duct to be made. It was found that the detached ribbed geometry has the advantage of eliminating the hot spots behind the attached ribs. Optimal clearance ratios for heat transfer enhancement between the present periodic detached ribs and previous single detached cylinder were also compared. Furthermore, compact heat transfer and friction correlations were developed for a detached ribbed duct for the first time.
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics,General Materials Science
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