Investigation of the nanofluid convective flow and entropy generation within a microchannel heat sink involving magnetic field

In this research, by studying the thermodynamics' laws, the thermal efficiency of microchannel was investigated employing the entropy analysis. Water is used as a base fluid with Al2O3 nanoparticles. Forchheimer -Brinkman model has been applied to include porous zone effect in momentum equations. The two-energy-equation model, which consists of two coupled equations, one for fluid and one for solid phase was employed. The analytical approach is applied to solve energy and momentum equations. The goal for using this method is the existence of nonlinear terms in equations. The effects of magnetic field, Reynolds number, α and ε on the parameters affecting irreversibility were studied. Then, it was concluded that by augmenting the Reynolds number to Reop, Ns decreases. Beyond Reop, the rise in Re enhance the Sgen and declines efficiency of the system. However, applying the magnetic field is beneficial between Re = 1.1 and Recr, and reduces the generated entropy. It was also observed that with the increase of α, Ns takes an upward trend. Increasing the ε value from 0.25 to 0.5 results in the downward trend of Ns, however, in high ε (0.75), Ns rises noticeably with augment of frictional irreversibility.