Comparative analysis of transient thermal behaviour and efficiency in longitudinal metal porous fin with combined heat and mass transfer under dehumidification conditions

Abstract

This investigation explores the transient thermal characteristics of longitudinal porous fins made of Aluminium (Al) and Copper (Cu), exposed to a dynamic moist airstream under dehumidification conditions. Heat and mass transfer processes are initiated when the fin surface temperature falls below the dew point temperature of the surrounding air, driven by differences in temperature and humidity ratios. Heat transfer within the porous structure is modelled using temperature-dependent convective coefficients and Darcy’s flow model, with the governing nonlinear partial differential equation transformed into dimensionless form and solved using the Finite Difference Method (FDM) to analyse the fin thermal profile and efficiency over time. These results reveal that Cu fin due to their superior thermal conductivity exhibit higher temperature profile and efficiency compared to Al fin across all pertinent parameters. A key finding is the significant impact of Relative Humidity (RH) on the thermal behaviour of the fin: as RH increases by 400%, the temperature distribution from base to tip decreases by 138% in Al due to its higher specific heat capacity, which enables it to absorb more latent heat and 85% in Cu, where the superior thermal conductivity allows for faster heat dissipation. As Darcy number (Da) decreases by 99%, the temperature distribution along the fin from base to tip increases by 0.058% in Al due to its lower thermal conductivity and 0.041% in Cu, where its higher thermal conductivity enables more efficient heat dispersion. These insights are pivotal for advancing fin design and optimization, facilitating improved thermal management in industrial applications under transient and dehumidifying conditions.