High performance heat transfer ducts with parallel broken and V-shaped broken ribs

Abstract

The effect of the broken rib orientation on the local heat transfer distributions and pressure drop in a square channel with two opposite in-line ribbed walls is investigated for Reynolds numbers from 15 000 to 90 000. The square channel is composed of ten isolated copper sections and has a length-to-hydraulic diameter ratio of 20. The rib height-to-hydraulic diameter ratio is 0.0625, and the rib pitch-to-height ratio equals 10. The results show that the 60° parallel broken rib or 60° V-shaped broken rib provides a higher heat transfer augmentation than the 45° parallel broken rib or 45° V-shaped broken rib and, subsequently, higher than the 90° broken rib. The parallel 'broken rib' or V-shaped 'broken rib' has 2.5-4 times heat transfer augmentation compared with the previous parallel 'continuous rib' or V-shaped 'continuous rib' with 2-3 times heat transfer augmentation for the same amount of 7-8 times pressure drop penalty. © 1992.