A proper water management is important for an efficient operation of a polymer electrolyte membrane (PEM) fuel cell system. The humidity distribution in the anode gas channels is highly dependent on the cathode humidity and the resulting transmembrane water transport. Therefore, it can be assumed that the cell humidification is optimal when the relative anode humidity is nearly 100% and homogeneously distributed.
In contrast to state‐of‐the‐art approaches, this study focuses on the humidity distribution on anode side in consideration of the anode recirculation loop.
Therefore, a macroscopic 1D+1D simulation model was developed, which simulates humidity profiles along the gas channels with consideration of the transmembrane water transport and the anode gas recirculation.
This study shows the impact of relevant input parameters, such as pressure, stoichiometry and cathode inlet humidity.
Furthermore, the results show that it is possible to reach a nearly homogeneous humidity distribution along the anode gas channels for automotive fuel cell systems. This can be achieved through appropriate operation conditions, e.g., suitable combination of pressure and stoichiometry, and supportive flow directions of the gases and the coolant. The analysis was made for fuel cells operating at full load at system relevant conditions with and without external humidification.
PEM fuel cell systems in automotive applications must provide a low minimum power compared to their maximum power. Especially systems without external humidification require a rather low stoichiometry and elevated pressure at the cathode to avoid dry-out at low load operation. Targeted experiments show that this may cause flooding, as the gas velocity becomes too low for sufficient liquid water drainage. An increase of the gas velocity would cause a membrane dry-out, negatively impacting the cells performance and lifetime. One solution for this issue is proposed in this work: a dynamic operation of the air system, which is periodically switched between one set point for membrane humidification and another one for liquid water drainage. A sophisticated experimental fuel cell system is used to test the proposed solution on a 100kW stack.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.