... Distributions of δ (%) versus Re f with φ as a parameter As far as the optimal particle loading is concerned, a number of distributions of φ opt versus T m and L/D are reported in Figs. 14 and 15 for different combinations of d p and Re f . First of all, it may be noticed that φ opt increases...

.... The fundamental result obtained is the existence of an optimal particle loading for maximum heat transfer. In particular, for any assigned combination of suspended nanoparticles and base liquid, it is found that the optimal volume fraction increases as the nanofluid average temperature increases, the nanoparticle...