Flow behaviour of glycolated water suspensions of functionalized graphene nanoplatelets

Abstract

The heat transfer performance of the conventional fluids used in heat exchange processes improves by dispersing nanoparticles with high thermal conductivity, as many researches have shown in the last decades. The heat transfer capability of a fluid depends on several physical properties among which the rheological behavior is very relevant, as we have previously pointed out. In this study, different samples of nanofluids have been analyzed by using a DHR-2 rotational rheometer of TA Instruments with concentric cylinder geometry in the temperature range from (278.15 to 323.15) K. The used base fluids were two different binary mixtures of propylene glycol and water at (10:90)% and (30:70)% mass ratios. Two different mass concentrations (viz. 0.25 and 0.5 wt.%) of graphene nanoplatelets functionalized with sulfonic acid (graphenit- HW6) were dispersed in these two base fluids. Firstly, with the goal of checking and calibrating the operation of the rheometer, the viscosity-shear stress curves for pure propylene glycol, Krytox GPL102 oil, and the two base fluids were experimentally determined. A detailed comparative study with those well-known data over the entire range of temperature was stabilized obtaining deviations in viscosity less than 3.5%. Then, the flow curves of the different nanofluid samples were studied at different temperatures to characterize their flow behavior.