1.2.4. The Effective Specific Heat Capacity Model

 *ρ cp n f* is the effective specific heat capacity of nanofluids, which is given by [24,25]

$$\left(\begin{pmatrix} \rho \ c\_{\mathcal{P}} \end{pmatrix}\_{nf} = \begin{pmatrix} \rho \ c\_{\mathcal{P}} \end{pmatrix}\_{f} \left[ (1 - \varphi) + \varphi \left( \frac{\begin{pmatrix} \rho \ c\_{\mathcal{P}} \end{pmatrix}\_{\text{CNT}}}{\begin{pmatrix} \rho \ c \mathcal{P} \end{pmatrix}\_{f}} \right) \right], \tag{4}$$

(*ρ cp*)*<sup>f</sup>* ,(*ρ cp*)*CNT* signify the specific heat capacity of the base fluid and CNTs, respectively.
