Validated Leverett Approach for Multiphase Flow in PEFC Diffusion Media

Abstract

The final paper in this series is devoted to delineating the effects of temperature on the multiphase transport characteristics of thin-film polymer electrolyte fuel cell (PEFC) diffusion media (DM). Direct measurements of capillary pressure-saturation of various commercial DM coated with a wide range of poly(tetrafluoroethylene) (PTFE) loadings (from 5 to 20wt%20wt% PTFE) were performed at different operating temperatures (20, 50, and 80°C80°C ). The benchmark data gathered from these experiments (available upon request) were compiled into the existing database generated from the first and second phase of this study, which examined the hydrophobicity and compression effects. The expanded database was then utilized to deduce a unified form of an empirical correlation appropriate for the tested DM. This semiempirical approach can predict capillary pressure of the tested DM as a function of liquid saturation, hydrophobic additive content, uncompressed porosity, compression pressure, and operating temperature within an uncertainty of ±14%±14% of the measured capillary pressure over the entire saturation domain, showing considerable improvement over the traditional Leverett approach.