Numerical model of dehumidifying process of wet air flow in open-cell metal foam

Abstract

Open-cell metal foam may improve the dehumidifying performance of the heat exchanger due to its high specific surface area, and the dehumidifying mechanism should be known for optimizing metal foam heat exchangers. In the present study, a numerical model for predicting the dehumidifying process of wet air flow in metal foam was developed. In the model, the contact angle function of the condensate on the metal fiber was developed based on the force analysis; the mass transfer during condensate formation process was calculated based on the heterogeneous nucleation rate and critical nucleation radius of condensate; the mass transfer for the condensate growth was developed based on the species conservation of water vapor on phase interface. The models of contact angle and mass transfer were introduced into the continuity, momentum and energy conservation equations as the momentum and mass source terms. The model validation results show that, the maximum deviations of predicted heat transfer and pressure drop from the experimental data are 11.9% and 17.7%, respectively. Based on the validated model, the influence of relative humidity and surface wettability on the dehumidifying performance of wet air in metal foam were discussed.