## 3 Results
### Thermophysical and Rheological Profiles  
The A-TiO\({}_{2}\)/PG:W 30:70 + PSS 1:4 nanofluids and base fluid thermal conductivity (\(k\)) were experimentally determined from 283 to 333 K in increments of 10 K, as depicted in Figure 7a. All samples show an upward trend in thermal conductivity as the temperature rises, reaching up to 10% increases within the temperature range. The 2.0 wt% A-TiO\({}_{2}\)/PG:W 30:70 + PSS 1:4 nanofluid showed the highest enhancement in thermal conductivity compared to the base fluid, with increments reaching up to 1.5%. These increases are 0.5% higher than those reported by [PERSON] et al. [19] for TiO\({}_{2}\)/PG:W 60:40 wt% nanofluids, who obtained increases of 1% for the 0.5 vol% concentration of TiO\({}_{2}\)/PG:W 60:40 wt% nanofluid. Regarding the experimental density (\(\rho\)), values were measured for both the nanofluids and PG:W 30:70 at various temperatures starting at 288 and up to 313 K with a 5 K temperature step, as shown in Figure 7b. Density decreases of 1.2% were observed for both the PG:W 30:70 and nanofluids when the temperature increased. Average increments ranging from 0.17% to 1.3% were found with the dispersion of A-TiO\({}_{2}\) nanoparticles. These increases are 4.5% lower than those reported by [PERSON] and [PERSON] [21] for TiO\({}_{2}\)/PG:W 30:70 wt% nanofluids (up to 5.8% for 0.8 vol% TiO\({}_{2}\)). The experimental A-TiO\({}_{2}\)/PG:W 30:70 + PSS 1:4 nanofluids isobaric heat capacities compared to those of the glycolated mixture are displayed in Figure 7c over the temperature range of 283 to 333 K with increments of 10 K. An increasing trend of the isobaric heat capacity can be observed with increasing temperature, reaching up to 4% higher values for PG:W 30:70 and up to 5.7% higher values for the 1.0 wt% A-TiO\({}_{2}\)/PG:W 30:70 + PSS 1:4 nanofluid at 333 K with regard to those at 283 K. Maximum average decreases of 13% with the dispersion of nanoparticles were found for the 2.0 wt% A-TiO\({}_{2}\)/PG:W 30:70 + PSS 1:4 nanofluid compared to the base fluid. This decrease is expected as a result of the reduced isobaric heat capacity of the A-TiO\({}_{2}\) (\(c_{p,p}\) = \(\sim\)0.687 J g\({}^{-1}\) K\({}^{-1}\)[32]) compared to PG:W 30:70 (\(c_{p,\,bf}\) = \(\sim\)3.986 J g\({}^{-1}\) K\({}^{-1}\) based on measurements conducted in the present study). These decreases are 14% and 9% less significant than those reported by [PERSON] et al. [20] for TiO\({}_{2}\)/PG:W 60:40 wt% nanofluids (27% and 19% at 243 K and 363 K, respectively). Concerning the rheological characteristics of the proposed nanofluids and base fluid, non-linear viscoelastic tests were carried out to evaluate the relationship between the shear stress and the shear rate. The resulting flow curves for the studied nanofluids, as well as the selected base fluid at 283 K within a shear rate range from 10 to 1000 s\({}^{-1}\), are depicted in Figure 8a and confirm the samples' Newtonian behaviour. Afterward, tests at a 100 s\({}^{-1}\) constant shear rate were performed to ascertain the dynamic viscosity values, as shown in Figure 8b, across the temperature range of 283 to 323 K. A diminishing trend in viscosity can be observed with the increasing temperature, reaching average decreases of 70% in dynamic viscosity values for all analysed samples. Increases in viscosity of up to 8.8% were found for the highest mass concentration of A-TiO\({}_{2}\) compared to the base fluid. The observed increases are in accordance with those reported by [PERSON] and [PERSON] [21] for TiO\({}_{2}\)/PG:W 30:70 wt% nanofluids (2.8%, 5.5%, and 11.5% for 0.1, 0.4, and 0.8 vol% concentrations, respectively), indicating minimal influence of surfactant addition on dynamic viscosity data. It was noted that thermal conductivity increases are not as high as those obtained in the literature. Nevertheless, dynamic viscosity increments significantly decreased, making it advantageous for heat transfer fluids to be used in thermal applications.