Nanoparticles shape effect on the efficiency of microheat sinks with tightly packed pin-fins

In this paper, the effects of the nanoparticles (NP) shape on thermal efficiency, entropy generation (Egen) for the application of a H2O/boehmite alumina nanofluid (NF) in a microheat sink (MHS) are studied. The MHS is composed of a number of microchannels, the walls of which consist of circular pin-fins attached together. A constant heat flux enters the HS from the bottom and heat it up. On the other hand, the nanofluid is responsible for cooling the HS. To study the thermal efficiency and entropy, a simulation using the control volume method has been performed in Fluent software. The effect of the NP size has been reported in this research. The simulation results showed that the average HS temperature strongly depends on the inlet fluid velocity, and an increase in the nanofluid velocity decreases it. Moreover, the addition of NPs reduces the average temperature of the HS, but its impact is smaller than that of the fluid velocity. Adding 5% of the cylindrical nanoparticles reduces the average temperature of the heatsink by 0.72 K. In addition, increasing the velocity and volume fraction of NPs decreases the thermal resistance (ThRes) and increases the pumping power. The addition of 5% platelet-shaped nanoparticles increases the pumping power required by up to 80%. Using cylindrical NPs leads to the best temperature uniformity and least thermal resistance in the HS. Adding NPs decreases entropy generation. Application of blade NPs in high volume fractions, as well as brick NPs in average volume fractions, leads the highest Figure of Merit (FOM).

Automated summary

This paper investigates the effects of nanoparticle shape on thermal efficiency and entropy generation in a microheat sink using a nanofluid. The results show that adding nanoparticles reduces the average temperature and thermal resistance of the heat sink, as well as decreases entropy generation.