A review on the properties, preparation, models and stability of hybrid nanofluids to optimize energy consumption

These days, the importance of energy consumption has led scientists to optimize thermal devices. One of the solutions proposed for this purpose is using solid nanoparticles to amend the thermal properties of conventional fluids. Adding the nanoparticles into the foundation fluids results in an improvement in the fluid properties (thermal conductivity, viscosity, etc.). Nanofluid (NF) has been drawing attention in various engineering applications in the past decade due to its superior heat transfer characteristics than the conventional working fluid. In recent years, the researchers have focused on adding two or more nanoparticles into foundation fluids, known as hybrid nanoparticles. Hybrid nanofluids (HNFs) suggest a more appropriate heat transfer performance and thermophysical features than the conventional heat transfer fluids (ethylene glycol, water and oil) and even NFs with single nanoparticles. It was proven that HNF can be an alternative to the single NF, since it can provide more heat transfer enhancement, particularly in the context of the solar energy, electromechanical, HVAC, electromechanical and automobile. In the current research, the properties, preparation and stability of HNFs are investigated. Also, some models and correlations for predicting HNFs properties are presented.