Multi-criterion optimization of thermohydraulic performance of a mini pin fin heat sink operated with ecofriendly graphene nanoplatelets nanofluid considering geometrical characteristics

This paper aims to examine and optimize thermal and hydraulic characteristics of an ecofriendly graphene nanofluid in a pin fin heat sink for cooling of electronic processors. The cylindrical fins with different diameters and heights are employed. By increasing each of the parameters of concentration, fin height and fin diameter, the bottom surface temperature decreases while the pumping power intensifies. Meanwhile, the temperature distribution becomes more uniform, which can decrease possibility of hot spot formation. The fin height has more significant effect on the temperature compared with the fin diameter. Although adding the nanoparticles improves the cooling noticeably, the pressure drop and pumping power do not experience significant variation. The surface temperature and pumping power are considered as the objective functions, and optimal values of the concentration, fin diameter and fin height are obtained for minimizing them. The compromise programming method is employed along with the genetic algorithm to include viewpoints of designer in the optimization. The fin height has a rather similar effect on the two objective functions, whereas the concentration and fin diameter vary the pumping power much lower than the surface temperature. Finally, employing the nanofluid with high concentrations is recommended for utilization in the heat sink. (C) 2018 Elsevier B.V. All rights reserved.