Out of the total energy harnessed directly and indirectly, 70% is produced by heat generation
[1]. Therefore, heat exchange systems must be better engineered for more efficient energy consumption. The improvement of conductive and convective heat transfer is one of the most significant scientific challenges in almost every industrial sector. This can be achieved by changing flow geometry, boundary conditions, or by enhancing thermophysical properties of the fluid. It has been proven over the years that thermal fluids are responsible for minimizing energy loss in heat transfer systems
[2,3][2][3]. Due to the exhaustion of natural resources and the increase in the demand for energy, it is very important to increase the energy efficiency of heat transfer devices. After many years of investigation, researchers have proved that nanofluids have the potential for improving the efficiency of heating and devices
[4,5][4][5]. Traditionally, heat dissipation is augmented by increasing the surface area of the system, but this leads to an undesirable size of the thermal management system. Therefore, the innovative concept of nanofluids has attracted great attention to maintain miniaturized systems with improved efficiency. The emergence of nanofluids has improved the heat transfer in the thermal systems like solar heat collectors, high power engines, microelectronic devices, and nuclear reactors
[6]. Nanofluids are homogeneous suspensions of nanoparticles in different base fluids such as water, ethylene glycol, lubricating oils, etc.
[7,8][7][8]. These nanoparticles upgrade the thermophysical properties such as viscosity, thermal conductivity, specific heat capacity (SHC), diffusivity, and density of the base fluids to a great extent. These suspended nanoparticles can be metallic, nonmetallic, metal oxides, and other compounds. Out of these, the suspensions of metal oxide nanoparticles are widely used due to their chemical stability, economy, and ease of production. Widely used metal oxide nano particles include Al
2O
3, SiO
2, TiO
2 and CuO
[9,10,11,12][9][10][11][12].
Maxwell originally proposed the theoretical model for improving the thermal conductivity of suspensions containing solid particles compared to the base liquid
[13]. When the density of coarse particles is high or the average particle size is large, the suspensions lead to a lack of stability, and it finally settles down. This leads to additional flow resistance and possible erosion in the components of the system. Fluids with suspended nanometer-scaled particles (less than 100 nm) are termed as nanofluids, a term proposed by Choi in 1995
[14]. These fluids are considered as next generation heat transfer fluids. The large surface area of nano particles enhances both the stability and heat transfer within the system. It also improves the abrasion-related properties as compared to the conventional solid–liquid mixtures.
Nano particles are classified as metallic and nonmetallic according to the material type. Depending on the constituent material type, stabilizing methods of the nano particles are varied. Among various nanofluids, metal-oxide based nanofluids are most widely applicable due to their long shelf life and chemical and thermal stability
[15].