K.F. Chiang

Detailed Heat Transfer Measurements of Curved Fin Channels

Detailed Nusselt number (Nu) distributions over six fin surfaces are presented for two sets of curved fin channels with twin- and single-flow exits that simulate flow passages in a cylindrical fin array for cooling of electronic chipsets. Each set of curved fin channels shares an identical cross-sectional shape with three different fin length (L)-to-hydraulic diameter (D) ratios of 22.5, 16.2 and 9.8. Influences of L/D ratio and exit condition on local Nu distributions over curve fin surfaces at Reynolds numbers (Re) of 500, 1,000, 1,200, 2,000, 4,000, 6,000, and 8,000 are examined. Spatially averaged Nusselt numbers () for two sets of tested channels are analyzed and compared that unravel the interactive impacts of L/D ratio and Re on heat transfer. In the present Re range, relative ratios between test channels with twin and single exits fall in the ranges of 0.97–1.08, 1.1–1.2, and 1.25–1.3 for L/D ratios of 22.5, 16.2, and 9.8, respectively. Heat transfer correlations for are generated using Re and L/D ratio as determining variables. A set of criteria for determining the optimal L/D ratio that provides the maximum cooling power available from a curve fin surface for the specified cross-sectional shape of curved fin channel are derived to assist the design activities for such cylindrical fin array.