Measurements of wall heat (mass) transfer for flow through blockages with round and square holes in a wide rectangular channel

Naphthalene sublimation experiments were conducted to study heat (mass) transfer enhancement by blockages with staggered round and square holes for turbulent air flows through a wide rectangular channel. The blockages and the channel had the same cross-section. The results showed that the blockages enhanced the average heat (mass) transfer on the channel walls by 4.7-6.3 times that for fully developed turbulent flow through a smooth channel. The blockages with round holes enhanced more heat (mass) transfer on the channel walls but caused larger pressure drops than the blockages with square holes, which had a 27% larger flow cross-sectional area.