Numerical evaluation of the impact of using spiral innovative turbulator on improving the thermal performance of a helical double-pipe heat exchanger

Abstract

Due to the necessity of performing thermal operations, heat exchangers are widely employed in many different areas. The heat transfer and fluid flow within a spiral double-pipe heat exchanger fitted with a novel turbulator were numerically assessed in this work. The presented novel turbulator is a curved tube with holes incorporated into its thickness and spiral ribs on its inner wall. The turbulator wall's curved rib design produces secondary flows at the turbulator output when fluid flows through the tube and the perforations. A commercial CFD tool, based on the finite volume technique, was used to conduct the numerical simulations. The fluid flow regime is turbulence (Re = 8,000 – 14,000). Two sections make up this work. The first portion looked at how the hydrothermal behavior of the fluid flow inside the proposed turbulator was affected by the angle at which the curved ribs rotated. For this angle, three values were considered: θ = 30, 90, and 150°, and the outcomes were contrasted with those of a plain spiral double-tube heat exchanger (turbulator not included). Then, the number of embedded holes in the turbulator's thickness changes in the second part, and three values of N = 12, 16, and 20 were considered. According to the first part's findings, the model exhibiting θ = 90° had a greater thermal performance factor at Re = 10,000. This model has a more noteworthy thermal performance factor than the models with θ = 150 and θ = 30° by approximately 15.62 % and 22.65 %, respectively (at Re = 10,000). Furthermore, the second section's numerical findings showed that the model with N = 20 had more extraordinary thermal performance at Re = 10,000. Model N = 20 has a thermal performance factor of about 16.93 % and 17.55 % greater than models N = 16 and N = 12. Within the proposed heat exchanger, the recommended turbulator produced a sizable rotating flow, and including embedded holes significantly reduced the pressure drop this kind of turbulator causes.

Keywords

• Heat transfer enhancement
• Heat exchanger
• Helical double-pipe
• Turbulators
• Numerical modeling
• Computational fluid dynamics