Orientation effects on mixed convective performance of twisted pin fin heat sink: Experimental investigation

In the current work, an experimental study is carried out to examine the heat transfer performance and friction effects on a pin fin matrix of a heat sink for different design variables and operating conditions. This examination aims to assess the thermo-hydraulic performance of the heat sink with three orientations (90°, 180°, and 270°). In the presence of three heat loads (66 W, 91 W, and 121 W), each of these orientations is tested with three twisting angles (30°, 60°, and 90°) for different pin fins cross-sections of square and hexagonal at various ranges of air Reynolds number (Re) (3182 to 9971). The downward position of a heat sink achieves a higher Nusselt number (Nu) than the sideward and upward positions. The fin pin with a twisting angle 30° has superior efficiency for three orientation angles and hexagonal and square cross sections. Square pin fin records the lower thermal performance at Re = 3182, orientation angle (β) = 270˚, and pin twist angle (θ) = 30°, and the best at Re = 9971, β = 180°, and θ = 90°. Compared to 60˚ and 90˚, the pin fins had a reduced pressure loss at a twisting angle of 30°.