Exact Analytic Heat Transfer from an Annular Fin with Stepped Rectangular Profile

Author(s):  
Antonio Campo ◽  
Balaram Kundu
Author(s):  
D. Chakraborty ◽  
G. Biswas ◽  
P. K. Panigrahi

A numerical investigation was carried out to study the flow and heat transfer behavior of a vertical circular tube, which is situated between two annular fins in cross-flow. The flow structure of the limiting streamlines on the surface of the circular tube and the annular fins was analysed. A finite volume method was employed to solve the Navier-Stokes and energy equations. The numerical results pertaining to heat transfer and flow characteristics were compared with the available experimental results. The following salient features were observed in this configuration. A horseshoe vortex system was formed at the junction of the stagnation line of the circular tube and the annular fin. The separation took place at the rear of the tube. The influence of the horseshoe vortices on local heat transfer was substantial. The ratio of the axial gap between two annular fins (L) to the radial protrusion length of the annular fin (LR) was identified as an important parameter. The flow and heat transfer results were presented for different L/LR ratios for a Reynolds number of 1000.


One method of increasing the heat transfer rate of the fins is by adding slits to the fins. The purpose of this study was to analyze the heat transfer rate by adding slits in the annular fins with a vertical cylinder under natural convection conditions. The vertical cylinder length, cylinder diameter, fin diameter, and distance between the fins are 313 mm, 25 mm, 125 mm, and 7 mm, respectively. The number of slits varied from 2 slits and 4 slits and the spacing of the slits was kept constant by 5 mm. This research was conducted with a simulation method using Autodesk CFD 2019 software. As a result, fins with slits and fins without slits were compared. The value of the heat transfer rate that occurs and the heat transfer coefficient in the annular fin with slits is better than the fin without slits. The highest heat transfer rates were 142.928 W and 2.6022 W/m 2K for an annular fin with 2 slits


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