Hybrid nanofluids with temperature-dependent properties for use in double-layered microchannel heat sink; hydrothermal investigation

The forced convection heat transfer through a double-layered microchannel heat sink is simulated by the finite volume method. The simulations are conducted under the conditions of constant Reynolds number and constant flow rate. The Al2O3-Cu/water and Al2O3-SiO2/water hybrid nanofluids with temperature-dependent properties and different volumetric concentrations are considered. The cooling capacities of these nanofluids are compared with that for pure water. The results showed that the base surface temperature is decreased by using both nanofluids compared to the base fluid at constant Reynolds numbers. The Al2O3-SiO2/water nanofluid has a better cooling capacity compared to Al2O3-Cu/water nanofluid as the Reynolds number is constant. At a constant flow rate, nanofluids with different volumetric concentrations do not affect the base surface temperature compared to the base fluid. The Al2O3-SiO2/water nanofluid gives lower thermal resistances compared to the Al2O3-Cu/water nanofluid but it has higher pumping power consumption than Al2O3-Cu/water nanofluid. The Al2O3-SiO2/water nanofluid has better Nusselt numbers compared to the pure water and Al2O3-Cu/water nanofluid. In general, increasing the volumetric concentration of both nanofluids reduces the thermal resistance and raises the pumping power consumption. © 2021 Taiwan Institute of Chemical Engineers