The effect of nanoparticle shape on hydrothermal performance and entropy generation of boehmit alumina nanofluid in a cylindrical heat sink with helical minichannels

Abstract

In the present paper, heat transfer, fluid flow characteristics and entropy generation of boehmite alumina nanofluid flowing through a cylindrical helical minichannels heat sink are examined numerically. The evaluated boehmite alumina nanofluid contain dispersed platelets, cylindrical, bricks and blades nanoparticles in a water. This evaluation is performed at two Reynolds number (i.e. Re=114.5 and Re=481.5) and four nanoparticle volume fraction (i.e.,φ= 0, 1%, 2% and 4%). The numerical Results reveal that the heat transfer, friction factor, pumping power, thermal performance factor an friction entropy generation are augmented and overall thermal resistance, heat transfer entropy generation, total entropy generation and augmentation entropy generation number are diminished by increasing Reynolds number and nanoparticle volume fraction for all studied shapes of nanoparticle. The highest and lowest heat transfer, friction factor, pumping power, thermal performance factor and friction entropy generation relate to the nanofluid containing platelets and bricks shapes nanoparticle, while the maximum and minimum overall thermal resistance, heat transfer entropy generation and total entropy generation belong to the nanofluid with the bricks and platelets shapes nanoparticle. The highest performance factor was achieved for φ= 4%, Re=114.5 by using platelets shape nanoparticles and this value is about 1.477.

Keywords

• cylindrical heat sink
• helical minichannels
• nanoparticle shape
• heat transfer
• entropy generation