Efficiency and Maximum Temperature of Fins of Complex Geometry

Abstract

Determining the efficiency of complex fins is important when performing calculations involving heat exchangers with individual finned tubes or continuous fin heat exchangers, i.e., plate-fin and tube heat exchangers (PFTHEs). Usually, these are circular or rectangular fins mounted on circular, elliptical, oval tubes or flattened tubes. With PFTHEs, the continuous fin is divided into virtual fins, which are either rectangular for an inline pipe layout or hexagonal for a staggered pipe arrangement. Maximum fin temperature is also important in light of a possible burnout of the material, especially when heat transfer from hot gas to fin is considered. This paper presents a procedure based on the finite element method (FEM) for determining the efficiency and maximum temperature of fins of any shape placed on tubes of any shape. It presents examples of calculating the efficiency of virtual fins in the most commonly used PFTHEs. It also depicts the efficiency of a fin as a function of heat transfer coefficient for the commonest two geometries and two more complex geometries in PFTHEs.