Numerical analysis of the magnetic field impact on hydrothermal characteristics of a microchannel heatsink with Fe₃O₄ ferrofluid and various pin-fin shapes

Enhancing the hydrothermal proficiency of thermal management devices by integrating active and passive heat transfer techniques is possible. Under magnetic field (MF), pin–fin heat sinks have rarely been studied in terms of frictional losses and coefficient of heat transfer (h). Here, with a nanoparticle concentration ratio of 2%, Fe₃O₄ ferrofluid flow inside a pin–fin heatsink was analyzed numerically considering various pin–fin shapes (rhumbas, squares, circles, and triangles) for absenteeism (WO) and attendance (W) of MF. In the results, the greatest and lowest gains for h were 13.12% and 8.8%, respectively, utilizing MF and Re = 200, for the circular and triangular heatsinks, which would be reduced to 5.36% and 2.41% by increasing Re to 500. In addition, h (and thermal resistance factor) in triangular configuration is 7.82–10.86% (and 4.98–8.68%) and 3.23–8.08% (1.94–6.22%) greater (and smaller) than that in the circular design under two scenarios of MF. Moreover, MF brings about a reduction of 1.86–0.60%, 1.61–0.46%, 1.71–0.54%, and 1.16–0.24% in T_m,CPU for the circular, square, rhumbas, and triangular configurations, respectively, within the Re range of 200–500. Although, when MF is present, pressure loss escalates by almost 6.39%, 4.97%, 3.60%, and 2.92% at Re numbers of 200, 300, 400, and 500 for each configuration, with the maximum pressure loss for triangular heatsink compared to the other arrangements. PEC factors at different Re numbers range from 1.51 to 1.87, suggesting an improved heatsink hydrothermal performance under MF impact compared to absenteeism of that. The highest/lowest PEC values at Re numbers 200 and 500 are associated with the rhumbas/triangular (1.871/1.782) and Triangular/square (1.547/1.496) configurations, respectively.