Thermal and flow analysis of microchannel heat sink (MCHS) cooled by Cu–water nanofluid using porous media approach and least square method

In this study, heat transfer of a fin shaped microchannel heat sink (MCHS) cooled by Cu–water nanofluid is investigated and temperature distribution in solid section (fin) and fluid section (Cu–water) are obtained by porous media approach and least square method and the results are compared with numerical procedure. The effective thermal conductivity and viscosity of nanofluid are calculated by the Parsher and Brinkman models respectively and MCHS is considered as a porous medium proposed by Kim and Kim. Modified Darcy equation is applied to the fluid and porous medium for heat transfer between fluid and solid sections. In addition, to deal with nanofluid heat transfer, a model based on Brownian-motion of nanoparticles is used. The effects of the nanoparticles volume fraction, porosity, Darcy number, microchannel dimensions, etc. on temperature distribution, velocity and Nusselt number are considered. As an outcome, by increasing the nanoparticles volume fraction, Brownian motion of the particles which carries heat and distributes it to the surroundings increases, and consequently difference between coolant and wall temperature will become less. Also, the optimum point for MCHS design is calculated by minimizing the friction factor which obtained channel aspect ratio (αs) is 2.45.