Pin-fin shape-dependent heat transfer and fluid flow characteristics of water- and nanofluid-cooled micropin-fin heat sinks: Square, circular and triangular fin cross-sections

The combined influence of pin-fin shape variation and utilisation of nanofluid coolants on heat transfer and fluid flow characteristics of a heat sink are investigated through the Lagrangian-Eulerian approach. The staggered arrangement of the square, circular and triangular cross-sectioned micropin-fins is evaluated for the parametric pressure range of 570 Pa ≤ ΔP ≤ 2760 Pa. The thermal performance of an aqueous-based alumina nanofluid is probed for a nanoparticle volume fraction and an average diameter of 0.5% and 20 nm, respectively. The heat transfer attributes are analysed in terms of thermal resistance (Rth), thermal contours, local (Nus) and average Nusselt number (Nuavg), whereas flow streamlines and velocity contours elaborate flow distribution across the heat sinks with variable pin-fin configurations. The results illustrate that utilising the nanofluid enhanced the heat exchange capacity of the heat sink regardless of the pin-fin configuration. However, an appropriate pin-fin shape can supersede the advantage of employing nanofluid coolants at the studied particle concentration. At the highest pressure drop, the nanofluid-cooled circular, square and triangular pin-fins demonstrated a maximum Nuavg enhancement of 23.1%, 16.5% and 8%, respectively, compared with water-cooled triangular pin-fins. While the Nuavgof water-cooled circular and square fins was noted to be 12.2% and 6% higher respectively, than that of the water-cooled triangular pin-fins.