Magnetic tunable thermal diffusivity of zinc ferrite/water nanofluid investigated using dual-beam thermal lens technique

In this study, we report how the zinc ferrite nanofluids constitute a great choice as heat transfer fluids due to their enhanced thermal diffusivity and magnetic tunability. The structure, morphology, magnetic and optical characteristics of nanoparticles in augmenting the thermal diffusivity were systematically analysed with a set of zinc ferrite nanoparticles synthesized at different calcination temperatures. Dual-beam thermal lens technique was then used to evaluate the thermal diffusivity of nanofluids, which demonstrated an increase of three times in thermal diffusivity than that of base fluid water. Subsequent experimental analysis performed in the presence of an external magnetic field revealed the magnetic tunability of thermal diffusivity for the first time with an estimated increase of six times than in the absence of a magnetic field. The optical imaging and field emission scanning electron microscopy of the nanofluid in the magnetic field supplemented the study in showing the significant effect of percolation due to the aggregate formation of nanoparticles being decisive in magnetic tunability of thermal diffusivity.