Fluid and heat transfer characteristics of aqueous graphene nanoplatelet (GNP) nanofluid in a microchannel

In the present work, thermo-physical properties of aqueous Graphene Nanoplatelet (GNP) at various mass concentrations of GNPs was experimentally measured. An experimental investigation was conducted to quantify the heat transfer coefficient, friction factor, pressure drop value, pumping power and thermo-hydraulic performance index of the nanofluid within a microchannel at various heat flux and Reynolds number. Results showed that GNP/water nanofluid can plausibly enhance the heat transfer coefficient and the Nusselt number by similar to 80%. In addition, a small increase in the friction factor and the pressure drop value was seen, which was attributed to the augmentation in the friction forces. The maximum increase in the pressure drop was 18.3% recorded at the highest Reynolds number and the highest mass concentration of the nanofluid. Also, despite the augmentation in the pressure drop value, the thermal performance of the system increased by 76% showing the great potential of the GNP/water nanofluid cooling and/or heating applications despite similar to 20% augmentation in the pumping power at Reynolds number > 1376. The enhancement in the thermal performance of the system was attributed to the thermophoresis effect, Brownian motion and the enhancement in the thermal conductivity of the nanofluid due to the presence of the GNP nanoplatelets.