%0 Journal Article %A Guan, Ning %A Jiang, G. L. %A Liu, Z. G. %A Zhang, C. W. %D 2019 %I Begell House %K hydrophobic surfaces, micro pin fins, contact angles, heat transfer, flow resistance %N 8 %P 799-820 %R 10.1615/HeatTransRes.2018026041 %T FLOW AND HEAT TRANSFER IN HYDROPHOBIC MICRO PIN FINS WITH DIFFERENT CONTACT ANGLES %U https://www.dl.begellhouse.com/journals/46784ef93dddff27,38007eb65e1e4a54,08ffd01158d24188.html %V 50 %X Hydrophobic micro pin fin heat sinks with contact angles θ = 99.5°, 119.5°, and 151.5° were prepared by solidifying hydrophobic layers containing nanoparticles on the surfaces immersed in flow, and the pressure drop, friction factor f, and the Nusselt number in hydrophobic micro pin fins were experimentally measured with liquid water as a working fluid. The friction factor reduction ratio df_coe and the Nu-reduction ratio dNu_coe in hydrophobic micro pin fins with different contact angles were obtained based on measurements, and the performing efficiency of heat transfer enhancement was analyzed in micro pin fins with different contact angles. The results demonstrated that the flow resistance was reduced apparently due to the hydrophobic surfaces, and the maximal value of df_coe in micro pin fins with θ = 99.5°, 119.5°, and 151.5° reached 0.52, 0.65, and 0.79, respectively. However, the Nu number in micro pin fins was also reduced due to the hydrophobic surfaces, and the reduction ratio of the Nu number became large with increase of the Re number at first and then became a constant value. Although heat exchange in micro pin fins was influenced by the hydrophobic surfaces, the comprehensive performance was improved over 100% in micro pin fins with θ = 99.5°, 119.5°, and 151.5° compared with the plain micro pin fins at a high heating load. %8 2019-03-18