University of Valenciennes,
Keywords: nanofluid, graphene, droplet evaporation, deposition pattern
Summary:With many extraordinary properties, especially the extremely high thermal conductivity, the graphene has potential applications in energy, electronic, medicine and so on. The addition of graphene nanoparticle to prepare water-based or ethylene-glycol-based nanofluid can significantly enhance the thermal conductivity of base fluid. In this study, the evaporation of droplets of graphene water-based nanofluid was investigated and recorded in an environmental chamber at different substrate temperatures by a side view CCD camera. The analysis of droplets profile provided the evolutions of contact angle, base diameter and volume throughout the evaporation process. The depositions left by evaporation were observed under an optical microscope which revealed an effect from substrate temperature. By increasing the substrate temperature, the evaporation time of nanofluid droplets decreased, but there is no change of contact angle and base diameter behaviors which were similar to those of water droplets. Contrary to high thermal conductivity, the total evaporation rate of nanofluid droplets, which was deduced by volume evolution, was lower than that of water droplets and the evaporation rate difference augmented with substrate temperature. More factors, for example dynamic viscosity, Marangoni flow, drop profile, nanoparticle shape, are considered in the determination of nanofluid droplet’s evaporation rate.