To determine the state of thermal conductivity in relation to the use of 20nm-sizd particles suspended in 60EGW, Sahoo et al. [38] focused on SiO2 as the selected nanofluids and set their experimental temperature at 20-90oC. Also, 20% was set as the experiment’s maximum concentration. Indeed, the state of enhanced thermal conductivity was reported to be 20%. However, these results only held when the temperature was 87oC and\(\varnothing=\)10%. It is also worth noting that Sundar et al. Al2O3 focused on the behavior of nanofluids by suspending Al2O3 particles in 60EGW, 40EGW and 20EGW base fluids – relative to their weights. To establish the values of thermal conductivity, the temperature ranges that characterized the experimental conditions were 20 to 60oC [39]. Also, the rate of concentration of the experimental materials was set between 0.3 and 1.5%. In the results, the authors reported 32.26% as the maximum rate of enhancement. These results held when 1.5% was set as the volume concentration, as well as 20EGW as the base fluid. Also, the results emerged after the temperature of the experimental conditions was set at 60°C [40].
In circumpolar countries and other cold regions such as Alaska and Canada, most of the industrial plants’ heat exchangers and automobiles have seen heat transfer fluids used widely. With subzero temperatures experienced, the fluids have also been used in building heating systems [37]. The eventuality is that propylene glycol or ethylene glycol have gained increasing use, having been mixed with water in varying proportions to serve the purpose of heat transfer [41]. However, propylene glycol solutions are seen to perform inferiorly compared to ethylene glycol solutions, with the factor of heat transfer property on focus. This outcome is also more pronounced in situations involving low temperatures. In situations involving cold climates, it is imperatively notable that 40% water and 60% ethylene glycol (translating into 40EGW is used [21,42]. However, the case of countries experiencing hot temperatures has seen this ratio altered to 60EGW (or 40:60). The alteration is informed by the affirmations that with pure water, it is challenging to maintain stability in these conditions [43]. In this investigation, the base fluid saw the water and EG mixtures’ ratios used as 40:60 and 60:40.
Other factors operating independent of the role of nano particles have been investigated and documented relative to the nanofluids’ thermal conductivity enhancement. Some of these factors include viscosity, temperature, and thermal conductivity. As such, this study strived to determine the thermal conductivity and viscosity properties of 40EGW and 60EGW base fluids. Given the base fluids, nano particles were dispersed, which SiO2 utilized as the nanofluids. In the section that follows, the manner in which the nanofluids were selected and prepared is described. The third section focuses on the experimental process that was employed towards investigating the viscosity and thermal conductivity of the materials. The fourth section offers the study’s resultant regression analysis, culminating into the fifth section that focuses on the experimental outcomes relative to the parameters of viscosity and thermal conductivity (in the form of a comparative analysis). Lastly, the sixth section provides a conclusion, which is a summary of the insights that were gained from this study.

Nanofluid Preparation Methodology

Initially, water forms a component of heat transfer, pointing to its wide-scale use as a liquid cooling applicant. Properties that account for this wide usage include low velocity and high thermal conductivity, as well as high heat capacity. The latter properties also imply that the fluid can be pumped easily. However, it is imperative to acknowledge that water exhibits a high freezing point, coming in the wake of the fluid’s associated low boiling point. Furthermore, failure to maintain the pH at a neutral level implies that water could prove corrosive. These trends have seen scholarly attention directed to the use of ethylene glycol. The growing use of the material is attributed to its antifreeze properties. Hence, ethylene glycol has been used in situations such as those involving chilled water air condition systems whose handlers or chillers are kept outside. Also, the material has gained growing use in systems requiring to be cooled at a freezing temperature that is lower than that of water [44]. Figure 1 below summarizes the flowchart of the methodology that this study employed.