Physical Properties and Rheological Characteristics of Activated Carbon Nanofluids with Varying Filler Fractions and Surfactants

For the past fifteen years, there has been considerable interest in the use of nanofluids in various fields mainly in heat transfer applications. This paper investigated thermophysical properties of activated carbon nanofluids using hexane, water and ethylene glycol (EG) as base fluids. Experimental and qualitative observational tests were conducted to study the viscosity, specific heat capacity and stability of the nanofluids using arabinogalactan (ARB), sodium lauryl sulphate (SDS) and TritonX-114 as stabilising agents. The results revealed that the addition of ARB to activated carbon-water (C/H2O) nanofluids yielded nanofluid stability for up to 39 days. However, ARB decreased the heat capacity of C/H2O nanofluid. C/H2O nanofluid viscosity decreased with an increase in shear rate. On the other hand, results revealed that C/C6H14 viscosity increased with the increase in shear rate specifically for high shear rate values. C/H2O heat capacity was enhanced by 6.1% compared to C/EG that decreased by 6.3%. Keywords: Nanofluids; Viscosity; Specific heat capacity; Surfactant; Stability.