Investigating the heat transfer performance and thermophysical properties of nanofluids in a circular micro-channel

In this paper, the thermal performance of a circular shaped copper microchannel heat sink using three types of nanofluids is discussed analytically. Al2O3–Water, TiO2–water and CuO–water nanofluids were used in this analysis and the comparative thermal performance of these three nanofluids is also discussed. The hydraulic diameter of the circular channel is 400 μm and the total block dimension is 10 mm × 10 mm × 4 mm. A steady, laminar and incompressible flow with constant heat flux is assumed in the circular channel. The analyses are done at various volume fractions ranging from 0.5 vol.% to 4 vol.% and at a constant inlet velocity of 1.5 m/s. The results showed that the thermal performance can be increased significantly by using CuO–water nanofluid as a coolant for cooling of electronic heat sink when Al2O3–water and TiO2–water nanofluids showed less improvement. Compared to pure water, the highest improvement (13.15%) in the heat flux occurred for 4 vol.% CuO–water nanofluid when Al2O3–water and TiO2–water nanofluids showed 6.80% and 6.20% improvements respectively. This improvement in heat flux is calculated without considering the additional required pumping power due to the increased viscosity of nanofluids. Therefore, CuO–water nanofluid can be recommended to obtain maximum heat transfer performance in a circular microchannel heat sink.