Boiling heat transfer enhancement and pressure drop analysis of Novec-649 in microchannel pin-fin heat sinks

With the rapid advancement of electronic and high-power devices in terms of performance and miniaturization, the need for efficient heat dissipation technology has become urgent. This research experimentally explores the effects of fin array shapes (circular, diamond, and drop-shaped) on boiling heat transfer and pressure drop characteristics of the dielectric fluorinated fluid Novec-649 under various mass flow rates, inlet temperatures, and vapor qualities. The results from high-speed camera show that the circular fin achieves the longest two-phase flow region, which is about 8.3% and 3.5% greater than that of diamond fin and drop fin. The extended two-phase region increases the phase-change heat transfer area and heat transfer coefficient, thereby improving the overall thermal performance of the circular fin. However, due to the shorter leading edge, drop-fin shows the lowest pressure loss across the heat sink among the three types of structures. Improved correlations for Nusselt number and pressure drop based on experimental data are proposed in this study with mean absolute percentage errors less than 10%.