Abstract: In this article, the thermal–hydraulic efficacy of a boehmite nanofluid with various particle shapes is evaluated inside a microchannel heat sink. The study is done for particle shapes of platelet, cylinder, blade, brick, and oblate spheroid at Reynolds numbers (Re) of 300, 800, 1300, and 1800. The particle volume fraction is assumed invariant for all of the nanoparticle shapes. The heat transfer coefficient (h), flow irregularities, pressure loss, and pumping power heighten by the elevation of the Re for all of the nanoparticle shapes. Also, the nanofluid having the platelet-shaped nanoparticles leads to the greatest h, and the nanofluid having the oblate spheroid particles has the lowest h and smallest pressure loss. In contrast, the nanofluid having the platelet-shaped nanoparticles leads to the highest pressure loss. The mean temperature of the bottom surface, thermal resistance, and temperature distribution uniformity decrease by the rise in the Reynolds number for all of the particle shapes. Also, the best distribution of the temperature and the lowest thermal resistance are observed for the suspension containing the platelet particles. Thereby, the thermal resistance of the nanofluid with the platelet particles shows a 9.5% decrement compared to that with the oblate spheroid particles at Re = 300. For all the nanoparticle shapes, the figure of merit (FoM) uplifts by elevating the Re, while the nanofluids containing the brick- and oblate spheroid-shaped nanoparticles demonstrate the highest FoM values.

Key words: Nanofluid, Thermohydraulic performance, Nanoparticle shape, Microchannel heat sink, Boehmite nanoparticles

摘要： In this article, the thermal–hydraulic efficacy of a boehmite nanofluid with various particle shapes is evaluated inside a microchannel heat sink. The study is done for particle shapes of platelet, cylinder, blade, brick, and oblate spheroid at Reynolds numbers (Re) of 300, 800, 1300, and 1800. The particle volume fraction is assumed invariant for all of the nanoparticle shapes. The heat transfer coefficient (h), flow irregularities, pressure loss, and pumping power heighten by the elevation of the Re for all of the nanoparticle shapes. Also, the nanofluid having the platelet-shaped nanoparticles leads to the greatest h, and the nanofluid having the oblate spheroid particles has the lowest h and smallest pressure loss. In contrast, the nanofluid having the platelet-shaped nanoparticles leads to the highest pressure loss. The mean temperature of the bottom surface, thermal resistance, and temperature distribution uniformity decrease by the rise in the Reynolds number for all of the particle shapes. Also, the best distribution of the temperature and the lowest thermal resistance are observed for the suspension containing the platelet particles. Thereby, the thermal resistance of the nanofluid with the platelet particles shows a 9.5% decrement compared to that with the oblate spheroid particles at Re = 300. For all the nanoparticle shapes, the figure of merit (FoM) uplifts by elevating the Re, while the nanofluids containing the brick- and oblate spheroid-shaped nanoparticles demonstrate the highest FoM values.

关键词: Nanofluid, Thermohydraulic performance, Nanoparticle shape, Microchannel heat sink, Boehmite nanoparticles