Experimental investigation of heat transfer enhancement in a stationary two-pass square duct with V-ribs

Abstract

This study focuses on evaluating the heat transfer augmentation and pressure losses in a stationary two-pass square duct with thermally active rib turbulators. Two different rib arrangements (90° and 60°-V) were investigated with a fixed blockage ratio (e/Dh) is 0.125 and the rib pitch-to-height ratio (P/e) is 10. The stainless steel foil is used as heater which practically ensures uniform heat flux boundary condition. Infra-red thermography (IR) technique has been employed to obtain the surface thermal maps and local Nusselt number distribution for three different Reynolds numbers namely, 20,000, 30,000, and 40,000. In addition, the effect of pitch has also been studied by using two pitch ratios namely, 10 and 20 for the same rib angle of 60°-V. The results reveal that the 60°-V shaped rib arrangement provides a higher thermal performance than the 90° ribs. 60°-V rib arrangement with higher pitch ratio shows poor performance compared to the lower pitch ratio cases.