Experimental investigation of heat transfer performance and frictional loss of functionalized GNP-based water coolant in a closed conduit flow

Abstract

The convective heat transfer coefficient and friction factor for fully developed turbulent flow of trimethylolpropane tris[poly(propylene glycol), amine terminated] ether-treated graphene nanoplatelet (TMP-treated GNP)-based water coolants are experimentally determined at constant velocity flowing through a horizontal copper tube with uniform heat fluxes. The TMP-treated GNP was first analyzed in terms of structure and morphology to confirm the GNP functionalization with TMP. The colloidal stability of TMP-treated GNP-based water coolant shows the high potential of the coolants for using in heat transfer equipment. Then, the experiments were conducted at a Re range of 3900–11 700 at constant velocity flow (1–3 m s⁻¹) and concentrations of 0.025 wt% to 0.1 wt%. The enhancement in thermal conductivity for TMP-treated GNP-based water coolants was between 20% and 31% compared to the basefluid. The convective heat transfer coefficient for the TMP-treated GNP-based water coolant was found to be up to 107% higher than the basefluid. The Nusselt number increased up to 72% at a heat flux of 23 870 W m⁻². However, the friction factor drop increases simultaneously in the range 4–10%. The results suggest that TMP-treated GNP-based water coolants could function well as working fluids in heat transfer applications and provide good alternatives to conventional working fluids.