2.3.2. For Methanol as the Base Fluid

The features displayed by methanol at room temperature according to the System International (SI) units is of density 790 kg·m−<sup>3</sup> whereas viscosity takes the numerical value 0.543 mPa·S, heat capacity is 2534 J/Kg m and thermal conductivity is 0.201 W·m−1·K<sup>−</sup>1.

• For gold nanoparticles

The mathematical expressions describing the thermophysical properties are given as:

$$\left(\overline{\rho}\_{nf}\right)\_{\text{methanol/gold}} = 790(1 - \phi) - 19300\phi\tag{29}$$

$$\left(\overline{\mu}\_{nf}\right)\_{\text{methanol}/\text{gold}} = 0.543 \left(1.013 + 0.092\phi - 0.015\phi^2\right) \tag{30}$$

$$(\overline{\rho}\mathbb{C}\_P)\_{\text{method}/\text{gold}} = (2543)(790)(1-\phi) - (126)(19300)\phi \tag{31}$$

$$\left(\tilde{k}\_{\rm nf}\right)\_{\rm methanol/gold} = 0.201(1.0204 + 0.0249\phi) \tag{32}$$

• For silver nanoparticles

For the methanol and silver nanofluids suspension, the physical properties of silver, heat capacity and thermal conductivity are 10,490,790 kg·m−3, 233 J/Kg m and 429 W·m−1·K−<sup>1</sup> respectively. Thus, thermophysical properties corresponding to this model are:

$$\left(\overline{\rho}\_{nf}\right)\_{\text{methanol/silver}} = 790(1 - \phi) - 10490\phi \tag{33}$$

$$\left(\overline{\mu}\_{nf}\right)\_{\text{methanol/silver}} = 0.543 \left(1.013 + 0.092\phi - 0.015\phi^2\right) \tag{34}$$

$$(\overline{\rho}C\_P)\_{\text{method/silver}} = (2543)(790)(1-\phi) - (233)(10490)\phi \tag{35}$$

$$\left(\overline{k}\_{\rm nf}\right)\_{\rm methanol/silver} = 0.201(1.0204 + 0.0249\phi) \tag{36}$$

In order to make a methanol and gold nanofluids suspension, gold density is 19,300 kg·m−3. The heat capacity and thermal conductivities are 126 J/Kg m and 317 W·m−1·K−<sup>1</sup> respectively.

### 2.3.3. For Ethanol as the Base Fluid

The features displayed by ethanol at room temperature have a density of 789 kg·m<sup>−</sup>3. The viscosity is 1.074 mPa·S, heat capacity is 2500 J/Kg m and thermal conductivity is 0.0235 W·m−1·K<sup>−</sup>1.

• For gold nanoparticles

For an ethanol and gold nanofluids suspension, the density of gold is 19,300 kg·m−3, and heat capacity and thermal conductivity are 126 J/Kg m and 317 W·m−1·K<sup>−</sup>1, respectively. Mathematically, it can be written as:

$$\left(\overline{\rho}\_{nf}\right)\_{\text{ethanol/gold}} = 789(1-\phi) - 19300\phi \tag{37}$$

$$\left(\left(\mathbb{T}\_{\text{nf}}\right)\_{\text{ethanol/gold}} = 1.074 \left(1.013 + 0.092\phi - 0.015\phi^2\right) \tag{38}$$

$$(\mathfrak{p}\mathbb{C}\_P)\_{\text{ethanol/gold}} = (2500)(789)(1-\phi) - (126)(19300)\phi \tag{39}$$

$$\left(\overline{k}\_{\rm nf}\right)\_{\rm ethanol/gold} = 0.0235(1.0204 + 0.0249\phi) \tag{40}$$

*Coatings* **2018**, *8*, 422
