Analytical methods for the efficiency of annular fins with rectangular and hyperbolic profiles under partially wet surface conditions
Numerical Heat Transfer, Part A: Applications, inpress., 19 pages
W. Pirompugd, S. Wongwises
Received : 6 July 2021
Accepted : 29 July 2021
Published online : inpress.
Abstract
In this study, we analytically investigate the performances of annular fins with rectangular and hyperbolic profiles under partially wet conditions. We propose four equations for the profiles of enthalpy difference, four equations for heat transfer rates, and four equations for fin efficiency which is a function of interface radius. We then present four equations for evaluating interface radius. Results indicate that the heat transfer rate and efficiency of an annular fin with a rectangular profile is higher than that with a hyperbolic profile. The efficiency under partially wet conditions is between those under fully dry and fully wet conditions. The efficiency of fully dry fins is independent of relative humidity; how- ever, for fully wet and partially wet conditions, efficiencies increase with decreasing relative humidity. At the same relative humidity, heat transfer rate increases with an increasing ratio of outside radius to inside radius. In contrast, fin efficiency decreases.
ต้น - วรเชษฐ์ ภิรมย์ภักดิ์ 