Effect of Sonication Time and Particle Volume Fraction on Thermal Conductivity of Alumina Nanofluids

The objective of this task was to use analytical modeling to determine thermal conductivity enhancement of nanofluid samples, with overall particle volume fraction, from 1% to 5%, at 70 W and 100 W. The highest thermal conductivity enhancement and maximum number of nanoparticle clusters were observed for different overall particle volume fractions and sonication times, at 70 W and 100 W. The second conclusion was, at both power levels, 4% volume fraction yielded nanofluids with highest thermal conductivity enhancement. For thermal conductivity enhancement from 16% to 35%, the maximum cluster size was on the order of 200 nm, while, for thermal conductivity enhancements from 135% to 173%, the maximum cluster size was restricted to 500 nm. Thermal conductivity enhancements in excess of 100% of the base fluid were achieved when the optimum overall particle volume fraction is 4%.