Numerical investigation of swirling flow and heat transfer of a nanofluid in a tube with helical ribs using a two-phase model

Abstract

In this investigation, fluid flow and heat transfer of the nanofluid in a tube with helical ribs are surveyed at a different volume fraction of nanoparticles $$\phi=$$ 0%, 1%, 2%, and 3% and Eulerian–Eulerian two-phase approach (mixture model) is used for simulating the water/Al2O3 nanofluid. The fluid flow is laminar, and simulation is done at Re = 250, 500, 750, and 1000. Also, four different geometric cases, including a plain tube and a tube with one, two, and three helical ribs, are used in this research. The most important surveyed parameters are the Nusselt number and friction factor. The results revealed that as Reynolds number increases, heat transfer increases, and friction factor decreases. The relative increase in Nusselt number and the relative decrease in friction factor at Re = 1000 than Re = 250 were calculated, respectively, 82% and 72% at $$\phi=$$ 0% in the plain tube. Helical ribs enhance the Nusselt number and friction factor and relative increase in Nusselt number, and friction factor in the tube with three helical ribs than the plain tube was calculated, respectively, 40% and 86% at $$\phi =$$ 0% and Re = 250. Finally, using nanofluid causes to increase in heat transfer and friction factor, and the relative increase in Nusselt number at $$\phi=$$ 3% than $$\phi =$$ 0% was calculated 6% at Re = 250 in the plain tube.