## 1 Introduction  
Heat exchange is an essential process in various industrial applications, and forced convective heat transfer occurs during heat exchange processes. Different properties of heat transfer fluids are significant for effective heat transfer. Increasing the heat transfer area of a heat exchanger, increasing the turbulence effect by changing the shape at the heat transfer channel entrance, and improving the heat transfer by reducing the channel size are some of the methods of increasing the heat transfer efficiency. However, these methods are limited due to various constraints in modifying the heat exchanger to enhance the heat transfer efficiency. Therefore, to improve the thermal properties of working fluids, researchers have synthesized heat transfer fluids using different nanoscale particles with high thermal conductivities with existing fluids and have performed various studies on them. These fluids are generally called nanofluids. Nanofluids are prepared by uniformly dispersing metal or non-metallic nanoparticles with high thermal conductivities in conventional working fluids such as water, oil, and ethylene glycol. The thermal conductivity of nanofluids is much higher than that of conventional working fluids. [PERSON] et al. [1] were the first to publish nanofluids, and various studies on nanofluids actively followed. Several studies have been conducted on the characteristics of the forced convective heat transfer for a single nanofluid. [PERSON] et al. [2] experimentally studied viscosity characteristics according to the concentration and size of Al\({}_{2}\)O\({}_{3}\) and TiO\({}_{2}\) nanofluids and the effect of surfactant addition. The results indicated that the viscosity decreased with increasing temperature, and the addition of a surfactant secured the dispersion stability of the nanofluid and increased the viscosity. The thermal conductivity and viscosity of Al\({}_{2}\)O\({}_{3}\) nanofluid were studied by [PERSON] et al. [3]. Different ratio of water-ethylene glycol (EG) was used as base fluid. The result showed that the thermal conductivity of the nanofluid was increased, and viscosity was decreased with the increase in EG percentage. [PERSON] et al. [4] confirmed an improvement of micro-convection of less than 10% by measuring the tracer diffusion coefficient of tert-butanol in a water-based silica nanofluid according to temperature and various concentrations. In addition, [PERSON] et al. [5] studied the flow and heat transfer characteristics of Al\({}_{2}\)O\({}_{3}\) nanofluids in microchannels using the lattice Boltzmann method. The experimental results confirmed that the average Nusselt number (Nu) increased as the Reynolds number (Re) and nanofluid concentration increased. [PERSON] et al. [6; 7] examined the heat transfer characteristics of various nanofluids in turbulent flow and confirmed their effect on improving the heat transfer performance of nanofluids. They also reported that the heat transfer was enhanced by approximately 18% in nanofluids with low concentrations (<2.00 vol%) at high temperatures. [PERSON] et al. [8] studied the forced convective heat transfer of a solar salt-based Al\({}_{2}\)O\({}_{3}\) nanofluid. They demonstrated that the specific heat and heat transfer coefficient increased by 12.3% and 7.26%, respectively, for a 2 wt% Al\({}_{2}\)O\({}_{3}\) nanofluid. [PERSON] et al. [9] made a review on the experimental and numerical studies of the control parameters that influence the natural convection in different shaped cavities with and without nanofluids. The forced convection can be increased by the addition of nanoparticles, magnetic fields, fins, and porous structures, but they reduce the free convection. [PERSON] [10] used the Prasher analytical model for calculating the thermal conductivity of nanofluids with Al\({}_{2}\)O\({}_{3}\), CuO, ZnO, and SiO\({}_{2}\) nanoparticles and water/ethylene glycol as base fluid. [PERSON] et al.