A Two-Dimensional Numerical Study of Heat Transfer in a Finned Tube Assembly During Axisymmetric Dehumidification

Abstract

This paper presents the analysis of two-dimensional heat transfer in an annular finned tube assembly during the process of dehumidification. All possible fin surface conditions, namely, dry, fully wet, and partially wet, have been studied and fin efficiency under these conditions have been modeled. Computations have been carried out using a control volume-based finite-difference method and compared with past one-dimensional analytical studies and available experimental data. The parameters that influenced the heat transfer rate in the finned tube structure are ratio of fin and wall thermal conductivities, ratio of fin thickness to fin pitch, ratio of wall thickness to fin pitch, ratio of fin length to fin pitch, cold fiuid Biot number, ambient Blot number, the relative humidity and dry bulb temperature of the incoming air, and the cold fluid temperature inside the coil. It was found that the heat transfer increased with increment in both dry bulb temperature and the relative humidity of the air. The fin efficiency changed rapidly with relative humidity under partially wet condition. The results suggest that coil performance can be very significantly altered by the condensation phenomenon on the fin surface and designs with dry fin data may not be adequate. The present results are expected to be very useful for the design of dehumidifier (cooling) coils for air conditioning applications.