The relationship between absolute vorticity flux along the main flow and convection heat transfer in a tube inserting a twisted tape

• Published in: Heat and mass transfer 2009-09, Vol.45 (11), p.1351-1363
• Main Authors: Lin, Zhi-Min, Sun, Dong-Liang, Wang, Liang-Bi
• Format: Article
• Language: English
• Subjects: Engineering; Engineering Thermodynamics; Heat and Mass Transfer; Industrial Chemistry/Chemical Engineering; Original; Thermodynamics
• ISSN: 0947-7411; 1432-1181
• DOI: 10.1007/s00231-009-0511-z

As passive enhancement devices, twisted tape insert has been used for almost a century, the most dominant heat transfer enhancement mechanism of circular tube fitted with twisted tape is the secondary flow generated by the tape. There is a parameter to specify the intensity of secondary flow, but this parameter cannot be applied to more general cases. Here cross-averaged absolute vorticity flux in the main flow direction is used to specify the intensity of secondary flow produced by twisted tape inserted in a tube. The relationship between the intensity of secondary flow and the intensity of laminar convective heat transfer is studied using a numerical method. The results reveal that the cross-averaged absolute vorticity flux in the main flow direction can reflect the intensity of secondary flow and a significant relationship between this cross-averaged absolute vorticity flux and Nusselt number exists for studied cases. The presented results validate that the cross-averaged absolute vorticity flux in the main flow direction is a general specifying of the intensity of secondary flow and can be used in other cases.