Thermal-hydraulic performance enhancement of modified hexagonal micro-Pin fin heat sinks using rotational configurations

Abstract

Nowadays, micro-pin fin heat sinks (MPFHSs) have shown promising performance in removing high heat fluxes in small dimensions and are widely used in electronic cooling applications. Among various techniques for thermal–hydraulic enhancement of MPFHSs, geometric design modification has been emphasized in this study, which focuses on investigating the orientation of the micro-pin fins (MPFs) as an overlooked but crucial parameter. To this end, rotational configurations of modified hexagonal MPFs, including co-rotation, alternating rotation, and counter-rotation have been investigated at rotation angles ranging from 0 to 60 degrees. In the numerical study, the copper MPFHS with a heat flux of 50 W/cm2 is cooled using water within the Reynolds number (Re) range of 400 to 1000. The results revealed that the rotation angle of MPFs governs the flow behavior around them. In general, counter-rotation configurations exhibited better thermal performance by providing the possibility of increased fluid mixing and contraction of low-velocity recirculation zones. However, the considerable increase in pressure drop in this configuration may limit its usability in higher Re regimes. By considering the compromise between pressure drop and heat transfer, the counter-rotation configuration with a 30-degree angle was selected as the optimal design. The optimized design results in an increase of approximately 50 % in Nusselt number (Nu) and up to 26.7 % in performance evaluation criteria (PEC). Furthermore, a supplementary experimental study confirmed the numerical results. It demonstrated the remarkable performance of the proposed design in removing heat fluxes ranging from 125 to 250 W/cm2, within the range of Re under investigation.