Partially wet fin efficiency for the longitudinal fins of rectangular, triangular, concave parabolic, and convex parabolic profiles

Abstract

Fins are used in many extended heat exchangers. Occasionally, they are used in fully dry or fully wet surface conditions. However, if the dew point temperature is in the range of the fin base and fin tip temperatures, a partially wet surface condition is present. In this study, the partially wet fin efficiencies for the longitudinal fin of rectangular, triangular, concave parabolic, and convex parabolic profiles are presented. However, for each profile, there are two methods to derive the partially wet fin efficiency that depend on a set of boundary conditions. In addition, eight equations of fin efficiencies are investigated. According to the derivation, the fin efficiencies are the function of the length of the dry portion. Thus, the equations for calculating the length of the dry portion must also be presented. The results indicate that the fin with larger cross-section has a higher conduction heat transfer rate and more fin efficiency. Moreover, the partially wet fin efficiencies decrease with an increase in relative humidity. The equation for predicting the partially wet fin efficiency from fully wet and fully dry fin efficiencies is also presented.