Numerical Simulation of Graphene-Nanoplatelet Nanofluid Convection in a Microtube Automotive Radiator

Abstract

This study investigates the convection performance of graphene nanoplatelets (GnP) in water-based nanofluid for microtube automotive radiators, with a focus on the impact of GnP concentration, nanoparticle size, and temperature on the thermophysical properties and heat transfer behavior. The results indicate that increasing GnP concentration raises the density but reduces the specific heat capacity of the nanofluid. Thermal conductivity improves with both higher GnP concentration and temperature, outperforming the basefluid by 667%. Conversely, viscosity increases with increasing GnP concentration but decreases with rising temperature. Using ANSYS Fluent, the study simulates the thermal performance of the microtube radiator and finds that at Reynolds numbers below 100, the average Nusselt number improves with both GnP concentration and Reynolds number, by as much as 1063%. However, above a Reynolds number of 100, the thermal performance deteriorates due to viscous dissipation. The study further reveals that reducing the inlet temperature increases the Nusselt number at high Reynolds numbers, while at low Reynolds numbers, both basefluid and GnP-water nanofluid show an enhancement in heat transfer. A decrease in nanoparticle thickness also enhances the Nusselt number when viscous dissipation is significant. The results suggest that the basefluid is more effective at high Reynolds numbers in a microtube automotive radiator, whereas the GnP-water nanofluid is better suited for low Reynolds number flows.