Measurement of liquid water accumulation in a PEMFC with dead-ended anode

The operation and accumulation of liquid water within the cell structure of a polymer electrolyte membrane fuel cell (PEMFC) with a dead-ended anode is observed using neutron imaging. The measurements are performed on a single cell with 53 cm(2) active area, Nafion 111-IP membrane, and carbon cloth gas diffusion layer. Even though dry hydrogen is supplied to the anode via pressure regulation, accumulation of liquid water in the anode gas distribution channels was observed in most tested conditions. Moreover, the accumulation of liquid water in the anode channels is followed by a significant voltage drop. Anode purges and cathode surges are also used as a diagnostic tool for differentiating between anode and cathode water flooding. The rate of accumulation of liquid water, and its impact on the rate of cell voltage drop is shown for a range of temperature, current density, cathode inlet RH, and air stoichiometric conditions. Operating the fuel cell under dead-ended anode conditions offers the opportunity to observe water dynamics and measured cell voltage during large and repeatable transients. (C) 2008 The Electrochemical Society.