Thermohydraulic performance of a nanofluid in a microchannel heat sink: Use of different microchannels for change in process intensity

Abstract

The effects of particle shape on the thermohydraulic performance of a boehmite nanofluid in a microchannel heat sink (MCHS) with different cross-sections are investigated. This investigation is performed for five nanoparticle shapes (platelet, cylinder, blade, brick, and oblate spheroid) at four Reynolds numbers in the MCHS with four cross-sections (i.e., circular, triangular, hexagonal, and elliptical). The MCHS with triangular microchannels demonstrates the greatest heat transfer coefficient, followed by the MCHSs with elliptical, hexagonal, and circular microchannels, respectively. The best temperature distribution and the lowest thermal resistance are realized for the MCHS with triangular microchannels. Moreover, the MCHS with circular microchannels results in the highest Figure of Merit (FoM), while the MCHS with triangular ones demonstrates the lowest FoM. The nanofluid with platelet particles causes the highest pressure loss, whereas the one with the Os-shaped particles has the lowest pressure loss. For all the nanoparticle shapes and cross-sections, uniformity of temperature distribution (θ) and thermal resistance reduce, while the heat transfer coefficient, pressure drop, and pumping power increase by rising the Reynolds number. Additionally, the colloid with the platelet-shaped particles causes the greatest heat transfer coefficient, pursued by the nanofluids with the cylinder-, blade-, brick-, and Os-shaped particles, respectively.