Synthesis and characterization of kerosene–alumina nanofluids

The present work investigates kerosene–alumina nanofluid for its stability, thermal conductivity and viscosity at low volume concentration of nanoparticles. The study intends to explore the possible application of using kerosene–alumina nanofluid in regenerative cooling channels of semi-cryogenic rocket engine. Nanofluid is prepared and characterized with varying particle loadings of 0.05%–0.5% by volume, in steps, for two different particle sizes of 13 nm and 50 nm. Oleic acid, as a surfactant, is used to stabilize the nanofluid and an optimum volume ratio of oleic acid to alumina particle is determined for enhanced stability of nanofluid. Dynamic Light Scattering (DLS) method is used to determine the average particle size in the nanofluid thus prepared with time. 22% enhancement in thermal conductivity and 10% in viscosity at room temperature are obtained for 13 nm particle size nanofluid at 0.5% volume concentration. Lower enhancement in thermal conductivity and viscosity are noticed for nanofluid prepared with bigger nanoparticles. The effect of temperature on thermo-physical properties is also determined and a non-linear increase in thermal conductivity with temperature is noticed. At elevated temperature, nanofluids show higher enhancement in their thermo-physical properties. A simple method for assessing the stability of nanofluid is attempted by measuring the thermal conductivity of nanofluid with time.