A Model for Panar Self-breathing Proton Exchange Membrane Fuel Cells in FEMLAB

Ziegler, C., Tranitz, M., Schumacher, J.O.
Fraunhofer Institute for Solar Energy Systems, Freiburg, Germany

A mathematical model of planar self-breathing fuel cells is developed and validated.

The geometry of the model is a two-dimensional symmetric element of a planar self-breathing fuel cell. The multicomponent transport of the species is considered as well as the couplings between the transport processes of heat, charge, and mass, and the electrochemical reactions.

The cell model is validated by comparison of the measured overall performance of a planar self-breathing fuel cell to the predictions of the model. The model is applied to study the behavior of planar self-breathing fuel cells during operation.

The results of this study show that the mass transport, the charge transport, the heat transport, and the electrochemical reactions are strongly coupled. The consideration of these couplings is essential for the validity of the simulation results. The gas distribution, the potential distribution, and the temperature distribution are influenced by the geometric design of the cathode end-plate. Thus the charge generation rate in the active area of the cathode and anode is affected by the ribs of the cathode end-plate. A strong nonuniformity of the current distribution over the cathode is found.

Based on the model, improvements of the fuel cell design and the components are suggested.