Investigating the effect of operating temperature on dynamic behavior of droplets for proton exchange membrane fuel cells

The present work depicts advanced understanding of dynamic behavior of droplets in serpentine channels for proton exchange membrane (PEM) fuel cells using a synchrotron-based X-ray radiographic technique at the Canadian Light Source (CLS). Due to high photon flux, the synchrotron-imaging technique provides high temporal and spatial resolution of images of water droplets in gas flow channels for PEMFCs. The whole cell and in particular, the gas diffusion layer (GDL) were operated under elevated temperatures through a self-designed heating channel around the GDL area (25-75 degrees C). In the experiments, a Sigracet 35 BC GDL was employed, and droplet height, chord and cycle time were measured over a series of images collected. Experimental results show that the droplet cycle time had been significantly reduced to less than 0.5 s from 14 s with an increase in the operating temperature from 25 degrees C to 75 degrees C. In addition, it is also found that increasing the operating temperature decreases the critical dimension of water droplets upon detachment i.e. from 0.46 mm for 25 degrees C to 0.33 mm for 75 degrees C. at a superficial gas velocity of 5.98 m/s. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.