Abstract
In this article, a numerical method was employed to perform an exergy analysis on water/boehmite alumina nanofluid in a pin-fin micro heat sink. The heat sink is a micro-sized component, which is in charge of cooling an electronic unit. Nanoparticles possess various shapes such as brick, blade, platelet, and cylinder. Hence, the effect of their shape was studied on exergy analysis, and the control volume approach was used for the simulation. The analysis revealed that the simultaneous increase in the velocity and volume fraction of all nanoparticle shapes decreases the output and gain exergy values, where the decrease in gain exergy is more significant. Brick-shaped nanoparticles exhibited the greatest reduction in out exergy. The reduction of out and loss exergies for brick-shaped nanoparticles is about 0.2W and 23W, respectively, when 5% of these nanoparticles are added to the base fluid. Furthermore, decreasing the inlet fluid velocity and increasing the volume fraction of nanoparticles reduce the amount of exergy loss. The study of the first and second laws of thermodynamics showed that increasing the velocity slightly increases the efficiency of the first law for both water and nanofluids, but reduces the efficiency of the second law of thermodynamics. In the case of water, the reduction in the efficiency of the second law is 5.9% for increasing the velocity from 0.2 to 0.8 m s(-1). Adding nanoparticles to water reduces both the efficiency of the first and second laws of thermodynamics.