Numerical study of thermal characteristics and pressure drop in a pipe equipped with innovative perforated and hollow spherical inserts

The present research has numerically investigated the heat transfer and thermal performance in a pipe with hollow and perforated spherical turbulators. Investigating the effect of aerodynamic turbulators with the same blockage percentage is a new topic for increasing heat transfer and reducing energy consumption in different industries. The used turbulators are spherical and have circular, oval, square and hexagonal holes. The best performance was obtained with the turbulator with an oval hole of 1.26. Then the effect of this turbulator with three different diameter ratios (DR = 0.65, 0.85, and 0.95) and three perforation indices (PI = 7%, 16%, and 24%) was studied. Air is used as a working fluid in turbulent flow, in the range of Reynolds number 6000 to 27,000. The present study has been analyzed using Ansys Fluent 19 software in three dimensions. The according to the results, the Nusselt number range is 1.58–5.02, and the friction coefficient is 3.55–13.99 times compared to the plain pipe in the studied geometries have increased, respectively. The thermal performance coefficient are in rangr of 0.77–2.13, and the highest thermal performance coefficient is obtained in DR = 0.85 and PI = 7%.