HEAT-TRANSFER PERFORMANCE COMPARISONS OF 5 DIFFERENT RECTANGULAR CHANNELS WITH PARALLEL ANGLED RIBS

This paper systematically presents the results of heat transfer and friction factor data measured in five short rectangular channels with turbulence promoters. The project investigated the combined effects of the channel aspect ratio, rib angle-of-attack, and flow Reynolds number on heat transfer and pressure drop in rectangular channels with two opposite ribbed walls. The channel aspect ratio (width-to-height, W/H, ribs on side W) varied from 1/4 to 1/2, to 1, 2, and 4, while the corresponding rib angles-of-attack alpha were 90-degrees, 60-degrees, 45-degrees, and 30-degrees, respectively. The Reynolds number range was 10,000,000. The results suggest that the narrow aspect ratio channels (W/H < 1) give much better heat transfer performance than the wide aspect ratio channels (W/H > 1). For the square channel (W/H = 1), the 60-degrees/45-degrees angled ribs provide the best heat transfer performance. For the narrow aspect ratio channel (W/H = 1/4 or 1/2), the 45-degrees/60-degrees angled ribs are recommended while the 30-degrees/45-degrees angled ribs are better for wide aspect ratio channels (W/H = 4 or 2).