Effect of varying Reynolds numbers on the heat transfer and flow structure of vertical, curved, inclined, and serpentine pin fins

Four different types of pin fins are discussed, namely vertical, curved, inclined, and serpentine pin fins, which vary from 10,000 to 50,000 in Reynolds number. In terms of heat transfer efficiency, curved pin fins were the most effective, consistently maintaining high efficiency across the range of Reynolds number studied. The serpentine pin fins show outstanding heat transfer at the endwall surface, with the phenomenon of extremely large values at the lower endwall and extremely small values at the upper endwall. The largest difference in overall heat transfer efficiency occurs at Reynolds number equal to 10,000 for curved and serpentine type fins, which are about 15.77 % and 7.84 % higher than the conventional vertical type fins. The inclined pin fin shows the lowest friction loss and maintains a decreasing trend. For the overall thermal performance factor, the differences between the serpentine and vertical pin fins are not significant, while the inclined pin fins show a clear tendency to increase after Reynolds number exceeds 40,000. Also at Reynolds number equal to 10,000, the differences are significant when compared to conventional vertical pin fins, with the inclined and serpentine pin fins showing increases of approximately 7.84 % and 24.22 %.