Recent advances on the fundamental physical phenomena behind stability, dynamic motion, thermophysical properties, heat transport, applications, and challenges of nanofluids

Abstract

Abstract For more than two decades, nanotechnology’s rapid development have created quite a lot of prospects for scientists and engineers. Nanofluid is one of the remarkable 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. Nanofluids are considered to offer substantial advantages over conventional heat transfer fluids. When dispersed uniformly and suspended stably in base fluids, a minimal amount of nanoparticles can significantly improves the thermal properties of host fluids. Present work attempts to address this challenge considering state-of-the-art advances in understanding, characterizing, and mitigating issues about nanofluids’ stability. Stable and highly conductive nanofluids are produced generally by, one step and two step production methods. Both approaches of creating nanoparticle suspensions suffer from nanoparticles’ agglomeration, which is a critical issue in all technologies involving nanopowder. Therefore, numerous numerical models and the principal physical phenomena affecting the stability (fundamental physical principles that govern the interparticle interactions, clustering and deposition kinetics, and colloidal stability theories) have been analyzed. Concerning the particles’ dynamic motion, the importance of different forces in nanofluid flows that exist in particulate flows such as drag, lift (Magnus and Saffman), Brownian, thermophoretic, van der Waals, and electrostatic double-layer forces is considered. Moreover, an overview of nanofluids’ thermophysical properties, physical models, and heat transfer models is​ included in this work. To understand the unexpected discoveries and overcome classical models’ limitations, several investigators have proposed new physical concepts and mechanisms and developed new models to enhance the transport properties. In the present work, the wide-ranging structural evolution of nanofluids has been discoursed thoroughly by sketching out a gargantuan depiction of the diminutive biosphere of nanofluids through a brief review of some foremost chronological 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 essential slip mechanisms of constructing heat transfer modeling of nanofluids have been discussed comprehensively in this study. Potential novel 2D materials as nanofluids have also been discussed and reported. A brief overview of the potential applications utilizing nanofluids has been reviewed, and future research gaps have been reported. Furthermore, recommendations were drawn regarding current knowledge gaps and future research directions to overcome the physical phenomenon, stability, thermophysical properties, overview of some applications, and the limitations hindering these nanofluids’ deployment. The review is presumed to be valuable for scholars and researchers working in the area of numerical simulations of nanofluids and experimental aspects and helps them understand the fundamental physical phenomena taking place during these numerical simulations and experiments and explores the potential of nanofluids both in academia and industry.