Synthesize of Hydrophilic Graphene and Experimental Investigation of Its Addition on the Improvement of Heat Transfer Coefficient in Water/Ethylene Glycol System

One of the common methods in the size reduction of heat transfer equipment is increasing the convective heat transfer coefficient of the base fluid. The main aim of this study is to produce hydrophilic graphene and investigating its potential in the improvement of convective heat transfer coefficient in water/ethylene glycol system in the cooling cycle. Graphene was synthesized via electrochemical methods and its stability in the water was enhanced via the loading of silica nanoparticles. The synthesized graphene was investigated via FT-IR and XRD analysis and SEM and TEM images and its successful fabrication was confirmed. The different weight percent of synthesized graphene-silica including 0.25, 0.5, 0.75, 1, 1.5% were added to water/ethylene glycol fluid to investigate the improvement of convective heat transfer coefficient with this nanofluid in an experimental designed setup. The obtained experimental data for Nusselt number and pressure drop for pure water fluid was compared with those calculated via the available models and it was found that the system is able to predict the results. The setup was examined with nanofluid with different concentrations of graphene/silica and it was found that by adding 1 wt.% nanoparticle into the based fluid the convective heat transfer coefficient improved at least 40% while the pressure drop showed about 30% increment. Overall, the findings of the current study support the potential of water/ethylene glycol/graphene-silica nanofluid for use in heat transfer equipment.