Analysis of Heat Transfer through Internal Fins Using CFD Tool.

Abstract

The rate of heat transfer of a fluid flowing in a closed enclosure can be increased with the modification in the closed enclosure. One of the approaches is by the use of internal fins. The present work, the vertical tubes carrying fluids by providing helical fins and checks its impact when subjected to natural convection heat transfer. All the main parameters which can significantly influence the heat transfer performance of finned tube has been analyzed. Natural convection in a vertical tube without fins was taken as the reference tube and different internal fin patterns such as a single fin with large no. of turns like coiled shape and large no. of fins with single turn is compared with reference tube on the basis of different parameters such as heat transfer rate, surface nusselt number, heat transfer coefficient, fin effectiveness etc. There are some dimensionless numbers which affect the natural convection such as Nusselt number which is the function of Reynolds number, grashof number and Prandlt number, Rayleigh number which is the product of grashoff and prandtl number. After getting best fin configuration compared it with a fin profile of rectangular cross section. All the computer simulation has been done on the ANSYS 13.0. The Naiver-stokes equations were used to solve for the fluid flow inside the tube and the Boussinesq approximation was used to get the buoyancy effect. Aluminum is used for the fin material and air is taken as the fluid flowing inside the tube and the flow is taken as laminar. It was found that the large number of fins with single turn is more efficient than other fin patterns, as there is less flow resistance, high heat transfer rate.