Numerical Comparison of Turbulent Heat Transfer and Flow Characteristics of SiO2/Water Nanofluid within Helically Corrugated Tubes and Plain Tube

Turbulent heat transfer in Helically Corrugated Tubes (HCT) was numerically investigated for pure water and SiO2 nanofluid using Computational Fluid Dynamics (CFD). This study was carried out for different corrugating pitches (5, 7, 8 mm) and heights (0.5, 0.75, 1.25 mm) at various Reynolds numbers ranging from 5000 to 13300. The effect of nanoparticles on heat transfer augmentation for plain tube and HCT was considered and the relative Nusselt numbers were also compared. However, the heat transfer extremely increased with increasing the volume fraction of nanoparticles in the plain tube but, the effect of helical corrugation on the heat transfer increment was much more than that of the nanoparticles enhancement in the HCT. It was concluded that the corrugated height increment and the corrugated pitch reduction increase the heat transfer process. The maximum heat transfer was obtained at Reynolds number of 13300, HTC with p=5 mm and e=1.25 mm, and SiO2 volume fraction of 1%.