Thermal and Hydraulic Performances of Porous Microchannel Heat Sink Using Nanofluids

Microchannel heat sink is an effective method in compact and faster heat transfer applications. This paper numerically investigates thermal and hydraulic characteristics of a porous microchannel heat sink (PMHS) using various nanofluids. The effect of porosity (gamma = 0.32-0.60), inlet velocity (w(in) = 0.5-1.5 m/s), and nanoparticle concentration (=0.0025 - 0.05) on thermal-hydraulic performance is systematically examined. The result shows a significant temperature increase (40 degrees C) of the coolant in the porous zone. The pressure drop reduces by 35% for gamma = 0.32 compared to the non-porous counterpart, and this reduction of pressure significantly continues when gamma further increases. The pressure drop with win is linear for PMHS with nanofluids, and the change in pressure drop is steeper for nanofluids compared to their base fluids. The average heat transfer coefficient increases about 2.5 times for PMHS, and a further increase of 6% in (h) over bar is predicted with the addition of nanoparticles. The average Nusselt number (Nu) over bar increases nonlinearly with Re for PMHS. The friction factor reduces by 50% when gamma increases from 0.32 to 0.60, and the effect of nanofluid on friction factor is insignificant beyond the mass flowrate of 0.0004 kg/s. Whilst Cu and CuO nanoparticles help to dissipate the larger amount of heat from the microchannel, Al2O3 nanoparticle appears to have a detrimental effect on heat transfer. The thermal-hydraulic performance factor strongly depends on the nanoparticles, and it slightly decreases with the mass flowrate. The increase of nanoparticle concentration, in general, enhances both (h) over bar and Delta P linearly for the range considered.

Automated summary

This paper numerically investigates the thermal and hydraulic characteristics of a porous microchannel heat sink using various nanofluids. The study examines the effect of porosity, inlet velocity, and nanoparticle concentration on the thermal-hydraulic performance.