Numerical investigation of external flow and conjugate heat transfer mechanism in finned tubes

The present numerical study has been carried out to investigate three dimensional, unsteady, turbulent flow over the finned tubes and conjugate heat transfer mechanism in the fins. It has been shown that, in this type of numerical problems, symmetry boundary conditions could cause unphysical results and therefore periodic boundary conditions should be used to get more accurate results. The available computional fluid dynamics (CFD) package FLUENT has been used to obtain the numerical solutions. However, special attention has been given to the modelling parameters of the complicated turbulent, unsteady flow.In the first numerical application, symmetry boundary condition was revealed to give inaccurate drag coefficient in the flow across an infinite circular cyclinder. Alternatively, periodic boundary conditions were used to get more accurate results. In the second numerical application, circular finned tubes in cross flow were investigated by using periodical boundary conditions instead of symetrical boundary conditions. The numerical flow visualizations were used to show more physical results. In the third and last application, unsteady, turbulent flow over polygonal finned tube banks-with two tubes was studied. Finally, this type of fins were proved to have a low surface efficiency which agree with literature review.Making comparison between present numerical results and literature studies, it was seen that chosen numerical modelling method and parameters are sufficiently reliable.Keywords: Finned tube, Conjugated heat transfer, Computational Fluid Dynamics (CFD)