Nanofluids transport through a novel concave/convex convergent pipe

The thermal and hydraulic performance of Al2O3-water nanofluid forced convective heat transfer through a concave/convex convergent pipe has been investigated in this work. The investigation is performed for a wide variety of concavity/convexity in the pipe wall profile, volume fraction of nanoparticles, and Reynolds number. An excellent agreement has been confirmed between the results of our numerical model and the available data from the literature. The findings of the current work reveal that as the pipe wall tends toward the concavity, the average heat transfer coefficient and the pressure drop along the pipe increase. Further, the concave wall profile shows a prominent enhancement in heat transfer up to 41%; while, the convex wall profile provides a sustainable and superior performance factor up to 1.223 compared to the straight one, respectively. Moreover, at any fixed wall profile, a modest rise in heat transfer and pressure drop has been observed when the nanoparticles volume fraction increases. According to the information provided in this study, the addressed configuration improvements play a crucial role in augmenting heat transfer more than employing nanofluids.