2.3.4. For Ethylene-Glycol as the Base Fluid

The density of ethylene-glycol at room temperature by System International (SI) units system is 1101 kg·m−3. The viscosity takes the numerical value 0.0162 mPa·S, heat capacity and thermal conductivity are respectively 2400 J/Kg m and 0.256 W·m−1·K<sup>−</sup>1.

• For gold nanoparticles

For an Ethylene-glycol and Gold nanofluids suspension, the physical property of gold density is 19,300 kg·m<sup>−</sup>3, heat capacity is 126 J/Kg m and thermal conductivity is 317 W·m−1·K<sup>−</sup>1. Accordingly, the mathematical expression can be written as:

$$\left(\overline{\rho}\_{nf}\right)\_{\text{ethylene/gold}} = 1101(1 - \phi) - 19300\phi\tag{45}$$

$$\left(\overline{\mu}\_{nf}\right)\_{\text{ethylene}/\text{gold}} = 0.0162\left(1.013 + 0.092\phi - 0.015\phi^2\right) \tag{46}$$

$$(\overline{\rho}C\_P)\_{\text{ethylene}/\text{gold}} = (2400)(1101)(1 - \phi) - (126)(19300)\phi \tag{47}$$

$$\left(\overline{k}\_{nf}\right)\_{\text{ethylene/gold}} = 0.256(1.0204 + 0.0249\phi) \tag{48}$$

• For silver nanoparticles

For the suspension of ethylene-glycol and silver nanofluids the physical property of silver density is 10,490 kg·m−3. The heat capacity and thermal conductivity are 233 J/Kg m and 429 W·m−1·K−1, respectively. On the previous contrast, mathematical expression can be attained as:

$$\left(\overline{\rho}\_{nf}\right)\_{\text{ethylene}/\text{silver}} = 1101(1 - \phi) - 10490\phi\tag{49}$$

$$\left(\overline{\mu}\_{nf}\right)\_{\text{ethylene/silver}} = 0.0162\left(1.013 + 0.092\phi - 0.015\phi^2\right) \tag{50}$$

$$(\overline{\rho}C\_P)\_{\text{ethylene}/\text{silver}} = (2400)(1101)(1 - \phi) - (233)(10490)\phi \tag{51}$$

$$\left(\overline{k}\_{nf}\right)\_{\text{ethylene/silver}} = 0.256(1.0204 + 0.0249\phi) \tag{52}$$

For the best understating of readers, the realistic physical properties of base fluids and nanoparticles are offered in Tables 1 and 2.


**Table 1.** Thermo-physical properties of the base fluids.

**Table 2.** Physical properties of the nanoparticles.

