Table 6.

Selected friction factor correlations from the literature

Correlation	Conditions	Range of validity
Hagen-Poiseuille correlation [73] f ⋅ Re = 64	Laminar flow inside circular channel	Re < 2300
Shah correlation [73] $f\cdot \mathrm{R}\mathrm{e}\approx \left(4\frac{3.44}{\sqrt{\xi }}+\frac{16+0.3125\xi -\frac{3.44}{\sqrt{\xi }}}{1+2.12\times \frac{{10}^{-4}}{{\xi }^2}}\right)$ Where $\xi =\left(\frac{\mathrm{x}}{\mathrm{D}}\right)/\mathrm{R}\mathrm{e}$	Laminar flow inside circular channel with consideration of entrance length	Re < 2300