Ex-situ experimental study on dynamic behaviors and detachment characteristics of liquid water in a transparent channel of PEMFC

A transparent model cell for direct ex-situ visualization of the dynamic characteristics of the growth, deformation and detachment of liquid water in the flow channel of the proton exchange membrane fuel cell (PEMFC) is designed. It fulfills the requirements of clear side imaging of water droplet behaviors in the channel. Different air velocities are implemented in the experiments to measure the droplet growth and detachment characteristics on the gas diffusion layer (GDL) surface. The results show that the droplet detachment time is shorter and detachment size is smaller with higher air velocity. Three stages of the droplet dynamic behaviors are defined, which are the growth, oscillation and removal stages of the droplet. The evolution of droplet dynamic contact angle and contact line at different stages is extracted and relevant characteristics are revealed. These results are important to quantitative characterization of droplet deformation and detachment on the GDL surface, and can also provide valuable parameters and validation for liquid water transport simulations in PEMFC.