Effects of pin fin shape and configuration on the single-phase heat transfer characteristics of jet impingement on micro pin fins

Experiments to investigate the effects of cross flow area and pin fin shapes on the single-phase impingement point heat transfer coefficients of jet impingement on micro pin fins have been performed. The micro pin fins were circular, hydrofoil, square, and elliptical pin fins with characteristic lengths ranging from 50 μm to 125 μm. Jet parameters were fixed with an orifice diameter of 2.0 mm and a stand-off ratio of 0.865. Using R134a as the working fluid, Reynolds numbers based on jet diameter were varied from 8000 to 80,000. Cross flow effects were found to have little to no significance on the heat transfer coefficients while area enhancement played a major role on the overall heat transfer enhancement. When comparing the various micro pin fins, the circular pin fins along with the square pin fins displayed the highest heat transfer coefficients for a given jet velocity.