Numerical Analysis of Airside Heat and Mass Transfer Characteristics of Fin-and-tube Heat Exchanger under Dehumidifying Conditions using VOF method

This paper presents a numerical study of the air-side heat and mass transfer characteristics of a single-row plain fin-and-tube heat exchanger with specific geometrical details under dehumidifying conditions using the volume of fluid (VOF) method with species transport.  Moist air, a combination of dry air and water vapor, is used as a working fluid.  The Lee model, which is embedded in ANSYS Fluent, is used to implement the phase change model.  Without additional source terms defined by user-defined functions, the default value is replaced with mass transfer time relaxation for condensation based on the density of the water liquid phase, the water vapor phase, and mass transfer time relaxation for evaporation. The effects of relative humidity and frontal velocity on heat and mass transfer are presented and discussed. The numerical results in terms of heat and mass transfer-based Colburn factors are validated against those found in the open literatures. The findings indicate that the effect of inlet relative humidity to temperature distribution, flow field and distribution pattern of water vapor mass fraction is small. The air-side heat and mass transfer coefficient are higher while the frontal velocity and inlet relative humidity are higher. The inlet relative humidity has little influence on air-side heat and mass performance when the frontal velocity is low.