An experimental study was made to obtain heat transfer data for a two-pass rectangular channel (aspect ratio=2:1) with smooth and ribbed surfaces for two channel orientations (90° and 135° to the direction of rotational plane). The rib turbulators are placed on the leading and trailing surfaces at 45° V-shaped orientation to the main stream flow. Two different arrangements of 45° V-shaped ribs are studied. The Reynolds number and rotation numbers were varied in 500040000, and 0.0-0.21, respectively. The rib height to hydraulic diameter ratio (e/D) is 0.094; the rib pitch-to-height ratio (P/e) is 10 and the inlet coolant-to-wall density ratio (Dpf) is maintained at 0.115 for all surfaces in the channel. The results show that the rotation induced secondary flow enhances the heat transfer of trailing surface first pass and leading surface second pass. However, the first pass leading and the second pass trailing surfaces show a decrease in heat transfer with rotation. The results show that 45° V-shaped parallel ribs arrangements produce better heat transfer augmentation than 45° V-shaped cross ribs, and a 90° channel orientation produces higher heat transfer effect over a 135° orientation.

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