The objective of this numerical work is to evaluate the first law and second law performances of a hybrid nanofluid flowing through a liquid-cooled microchannel heatsink. The water-based hybrid nanofluid includes the Fe3O4 and carbon nanotubes (CNTs) nanoparticles. The heatsink includes a microchannel configuration for the flow field to gain heat from a processor placed on the bottom of the heatsink. The effects of Fe3O4 concentration (uFe3O4 ), CNT concentration (uCNT) and Reynolds number (Re) on the convective heat transfer coefficient, CPU surface temperature, thermal resistance, pumping power, as well as the rate of entropy generation due to the heat transfer and fluid friction is examined. The results indicated higher values of convective heat transfer coefficient, pumping power, and frictional entropy generation rate for higher values of Re, uFe3O4 and uCNT. By increasing Re, uFe3O4and uCNT, the CPU surface temperature and the thermal resistance decrease, and the temperature distribution at the CPU surface became more uniform. To achieve the maximum performance of the studied heatsink, applying the hybrid nanofluid with low uFe3O4and uCNT was suggested, while the minimum entropy generation was achieved with the application of nanofluid with high uFe3O4and uCNT.
