Simultaneous Investigation of PEMFC Performance and Water Content at Different Flow Rates and Relative Humidities

Abstract

In order to prevent membrane dehydration and flooding in proton exchange membrane fuel cells (PEMFC), appropriate water management must be done. Therefore, accurate knowledge of the effects of various parameters on cell water content is needed. This knowledge helps to achieve optimum cell performance. The effects of both anode and cathode stoichiometry and relative humidity on single serpentine PEMFC performance and flow channel water content are surveyed experimentally. All tests conducted on transparent fuel cell with serpentine flow field channels and 25cm2 MEA active areas. Digital image processing is performed on the captured images of cathode channel to detect accumulated water at that side. The results indicate that there is a correlation between water content of cathode flow channels and cell performance. Increasing cathode water content causes membrane hydration which leads to better cell performance, but high water content causes flooding. It is concluded that both stoichiometry and relative humidity have significant effect on cell performance. Increasing reactant relative humidity improves water transport mechanisms within the cell, but fully humidified reactants may causes flooding. Although high stoichiometry rate prevents flooding and facilitate reactants transport within catalyst layer, high anode and cathode stoichiometry leads to membrane dehydration. Experimental observation shows that both stoichiometry and relative humidity have optimum value.