Endwall heat transfer and pressure drop in scale-roughened pin-fin channels

There is a growing requirement for improved heat transfer performance for a number of electronic devices and this dictates a need to further elevate the endwall heat transfer performances for pin-fin channels. Driven by this need, a novel compound heat transfer enhancement (HTE) measure that combines deepened scales and pin-fin array is devised. Characteristics of heat transfer and pressure drop performances in two scale-roughened pin-fin channels with two different pin pitch-to-diameter ratios are compared for both forward and backward flows in the Reynolds Number (Re) range of 1000-30000. Comparisons of heat transfer data, pressure drop measurements and thermal performance factors with previous results collected from a variety of single and compound HTE devices demonstrate the significant augmentations in both heat transfer rates and pressure drop coefficients for the present HTE measure. This present compound HTE measure with scales and pin-fin array demonstrates an enhancement on the heat transfer up to of 22 times of the developed flow references in smooth-walled pipe within the Re range of 1000-30000. Experimental correlations of heat transfer and pressure-drop coefficients for two scale-roughened pin-fin channels with forward and backward flows are derived to assist design applications.