Fundamentals of nanofluids: evolution, applications and new theory

Abstract

In the past decade, quick developments in nanotechnology have created quite a lot of prospect for the scientists and engineers to check up. Nanofluid is one of the amazing consequences of such progression. Nanofluids are engineered by suspending nanoparticles with average sizes below 100 nm in traditional heat transfer fluids such as water, oil, and ethylene glycol etc. Nanofluids are considered to offer important advantages over conventional heat transfer fluids. A very small amount of guestnanoparticles, when dispersed uniformly and suspended stably in base fluids, canprovide dramatic improvements in the thermal properties of host fluids. Stable and highly conductive nanofluids are produced by generally, one-step and two-step production methods. Both approaches to creating nanoparticle suspensions suffer from agglomeration of nanoparticles, which is a key issue in all technology involving nanopowders. In trying to understand the unexpected discoveries and so to overcome the limitations of classical models, a number of investigators have proposed new physical concepts, mechanisms, and developed new models for enhancing the transport properties. In the present work, wide-ranging fundamental evolution of nanofluids have been discoursed thoroughly by sketching out a gargantuan depiction of the diminutive biosphere of nanofluids through a brief review of some chronological foremost milestone such as the concepts of nanofluids, the preparations and performances of nanofluids, conductivity, viscosity and density correlations of nanofluids, and potential applications and benefits of nanofluids. Also, different kinds of modeling and very important slip mechanisms of constructing heat transfer modeling of nanofluids have been discussed comprehensively in this study. Furthermore, we have established new mathematical equations theoretically for electrical conductivity and thermophoretic velocity in nanofluids as well as nanoparticles mass flux equation due to Brownian diffusion and thermal diffusion which can be used for general transport nanofluids modeling. Our results of thermal diffusion coefficient are also justified by the experimental findings.