A Review on Thermophysical Property Assessment of Metal Oxide-Based Nanofluids: Industrial Perspectives

Energy consumption in the industrial sector can be significantly reduced by improving heat transfer rates in heat exchanger circuits, pool boiling, metal cutting industries, etc. Numerous energy-related issues can be overcome to a large extent by improving heat flow properties by utilizing nanofluids. The present contribution reviews the improvement in thermophysical properties of metal oxide-based nanofluids. Key parameters affecting the thermophysical properties of nanofluids, such as particle volume fraction, temperature, particle size and various stabilizers, were reviewed. The importance of DLVO theory and zeta potential to control the electrostatic repulsion and pH values of nanofluids for stable nanofluid formulations were discussed. It has been observed that classical theories of thermal conductivity and viscosity cannot predict exact values for a wide range of variables. Therefore, various extensive correlations have been introduced to predict the thermophysical properties of nanofluids. In these correlations, individual dependent variables such as particle size, temperature, nanofluid layer thickness, and Brownian velocity of nanoparticles, etc. were considered for more accurate prediction. The heat transfer efficiencies of nanofluids to base fluids in the laminar and turbulent regimes have been discussed using various figures of merits. Finally, the scope of industrial applications of metal oxide-based nanofluids and future research opportunities have been discussed.