Ex-situ probing of PEFC liquid droplet dynamics in the presence of vibration

PEFC performance degradation when exposed to vibration has been attributed to liquid water redistribution; however, fundamental liquid droplet behavior under such conditions is not well understood. As this technology continues to penetrate automotive, aerospace, and marine markets, where vibration and mechanical shock may be common, it is necessary to characterize droplet dynamics under such conditions. This work uses ex-situ experimental techniques to study the effects of sinusoidal vibration on water and gas-diffusion layer interactions for open cathode and flow channel based designs. Parameters such as contact angle, key droplet dimensions, adhesion force, and detachment velocity were measured for a range of frequencies and amplitudes. Vertical and horizontal oriented cells were investigated. The results show that vibration can significantly impact wetting; in some cases, increasing the barrier for liquid removal. Sessile droplet contact angle and dimensions such as height and wetting diameter, shifted toward more hydrophilic wetting under elevated frequency. Droplet detachment velocities were measured to be higher at 100 Hz then at 0 Hz for air speeds up to 10 m s−1. These results may be of interest to PEFC modelers and flow-field designers.