Characterizing the two-phase flow effect in gas channel of proton exchange membrane fuel cell with dimensionless number

Abstract

A simplified one-dimensional proton exchange membrane fuel cell (PEMFC) model is developed to characterize the two-phase flow effect with dimensionless numbers. A new Damköhler number is defined to decouple the gas and liquid flow in electrodes. The flow pattern in gas channels can be predicted by force balance analysis with Reynolds number and Weber number. The effect of two-phase flow patterns in bipolar plate gas channel on mass transfer at the gas channel-gas diffusion layer (CH-GDL) interface can be represented by Sherwood number. Then, the influence of relative humidity, cathode stoichiometric ratio, operating temperature and dimensionless width of water film/slug are studied. The results indicate that the two-phase flow occurring at high humidity and current density can be accurately predicted with dimensionless numbers. The output performance of fuel cell dropped by 10–100 mV due to the additional mass transfer resistance caused by liquid water in bipolar plate gas channels. Therefore, the present model can reflect the main two-phase transport effects with low computational cost and contribute to the efficiency and accuracy of PEMFC design and control.