Heat transfer analysis in a circular tube with internal fin by numerical method

Abstract

Heat transfer through an internally finned tube has been done by numerical simulation technique. The pipe is assumed to be fitted with internal longitudinal fin having three different half included angle, via. 14o, 16o and 18o. The fin/tube material is assumed as aluminium and copper. The fluid flowing through the tube is taken as water and engine oil. The governing partial differential equation for fluid flow and heat transfer are converted into linear algebraic equation by pure implicit finite difference method. In the implicit scheme the known nodal properties are written in terms of unknown nodal properties. Genetic programming is used to express the Nusselt number and bulk temperature in terms of inlet properties of the fluid and boundary condition The Nusselt number is maximum at the entrance, decreases along the length of the pipe and reaches a constant value when the flow becomes fully developed. The pipe with half included angle 14o gives higher Nusselt number when compared with other two fins. This is due to the higher surface area of the fin with half included angle 14o which keeps the tube surface relatively at lower temperature. Nusselt number is independent of heat flux, thermal conductivity of tube material and depends on Reynolds number and thermal conductivity of the coolant. Effectiveness is independent of heat flux, Reynolds number and thickness of the tube for the given coolant. It is high for the coolant with lower thermal conductivity. The bulk temperature depends on heat flux, specific heat of the coolant and Reynolds number and independent of the thermal conductivity of the tube wall. So, it is concluded that the fin with half included angle of 14o enhances the heat transfer by 2.53 times that of the unfinned tube. For the given heat flux, increase in thickness of the tube increases the bulk temperature and decreases the Nusselt number. The present result deviates from the literature by about 10% because of variable pressure gradient and specific heat capacity along the length of pipe. newline newline