Ex situ and modeling study of two-phase flow in a single channel of polymer electrolyte membrane fuel cells

In this study, we investigate the air–water two-phase flow in a single flow channel of polymer electrolyte membrane (PEM) fuel cells. In the ex situ study, both straight and serpentine channels with various gas diffusion layer (GDL) surfaces are studied. Focus is placed on the two-phase flow patterns, which are optically characterized using a microscope with a high-resolution camera, and the two-phase pressure amplifiers. We find that the GDL surface properties slightly affect the flow pattern and two-phase pressure amplifier in the flow field configuration. Flow pattern transition occurs at the superficial gas velocity of around 1 m s−1, and the pressure amplifier can reach as high as 10. A two-fluid model is also presented together with one dimensional (1-D) analytical solution, and acceptable agreement is achieved between the model prediction and experimental data at high gas flow rates.

► Ex situ investigation of air–water two-phase flows in PEM fuel cell channels was conducted for different channel configurations and surfaces on the GDL side.
► A two-fluid model was presented and analytical solution was derived.
► We found flow regime transition occurs around the gas superficial velocity of 1 m s−1 for the considered channel.
► The two-phase pressure amplifier in all the three cases can reach around 10 at the gas superficial velocity of 0.5 m s−1, and is reduced to 1 when the gas flow rate is sufficiently high.
► Model prediction compares with the experimental data at high gas flow rates, showing an acceptable agreement.