Enhancement of heat transfer by inclined holes through perforated heat sinks

The effects and enhancement of inclination angle ( θ ) in perforated heat sinks were investigated using Computational Fluid Dynamics ( CFD ) by implementing the Finite Volume Method for discretization . A perforated heat sink with three holes and varying inclination angles was analyzed to evaluate the impact of inclination angle on heat transfer, case maximum temperature, turbulent kinetic energy , pressure drop, friction factor ratio , and thermal performance factor across the specified Reynolds number range. Reynolds number (3500 ≤ Re ≤ 6500) and inclination angle ( θ = 30°, 45°, 135°, 150°) were considered as parameters and inclined holes were compared with straight perforated pins ( θ = 0°) to interpret the effect of inclination angle. The validated model showed that heat transfer enhancement increased by 4.2 %–8 % with increasing inclination angle, while the system maximum temperature decreased by 4.5 %–5.6 %. Although the pressure drop was higher compared to straight perforated pins, it was found to be largely unaffected by the inclination angle. However, the inclination angle was observed to increase the friction factor rate by 6.7%–16 % compared to straight perforated pins. Considering the pressure drop alongside enhanced heat transfer, the thermal performance factor ( η ) demonstrated that inclined holes performed better than straight holes. For thermal applications, the inclination angle of θ = 135° was reported as the optimal value, providing an 8 % increase in the Nusselt number and a 6 % reduction in the maximum system temperature. This improvement, however, was slightly reduced for θ = 150°, indicating that the inclination angle should only be increased up to a certain value. The benefits were attributed to improved turbulent mixing, as the turbulent kinetic energy between the pins was found to increase significantly.