CFD Analysis of Fin and Tube Heat Exchangers using ANSYS CFX

Abstract

Generally, Heat exchangers used in cryogenic applications are required to have very high effectiveness to preserve the refrigerating effect produced and their effectiveness values lie in the order of 0.95 or higher. If the effectiveness of the heat exchangers falls below the design value, there may not be any liquid yield. This stringent requirement of high effectiveness besides high pressure drops, makes it a necessity to test any given heat exchanger model, before putting it into any operation for such purposes.
Fin and tube exchangers, because of their compactness, low weight and high effectiveness, are widely used in aerospace and cryogenic applications. Such heat exchangers have closely spaced fins and offer narrow and intricate passages for the fluid flow which often leads to significant pressure drop.
Extensive research has been done on finned tube heat exchangers over the last few decades to understand the heat transfer phenomena occurring therein and to determine the dimensionless parameters ie., heat transfer coefficient “h”, colburn factor “j” and the friction factor “f”. But, theoretical analysis done on design of the above mentioned fin heat exchanger often suffers from errors due to oversimplification of fin channel geometry and assumptions made. Experiments on heat transfer over plate fin surfaces are also expensive and difficult.
So to solve this problem, the current project is focussed on CFD analysis of fin and tube heat exchanger using ANSYS CFX software to evaluate its performance parameters under specified conditions and establish comparison between plain fin and wavy fin models of the above mentioned heat exchanger.