Particle size and concentration effect on thermal diffusivity of water-based ZnO nanofluid using the dual-beam thermal lens technique

In the present work, we experimentally investigate the size and concentration dependence of the thermal diffusivity of water-based ZnO nanofluid. The results show an increase in thermal diffusivity both by increasing the particle size from 5.6 to 16.6 nm as well as nanoparticle concentration in the range 0.02–0.1 mg/ml. It was also observed that there is a 4% enhancement in thermal diffusivity of the nanofluid for an optimum value of nanoparticle size and concentration. The dependence of thermal diffusivity on the particle size and concentration can give a great insight into the inter-particle interaction and the aggregation dynamics in nanofluid.