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 face highly dynamic load profiles in automotive application. This work showcases the impact of media supply adaption, system architecture and test rig restrictions on the transient voltage response of an automotive fuel cell stack. Current step and load profile experiments were conducted on a system test rig, featuring automotive balance of plant components, and a short stack test bench. A time scale analysis allowed us to identify the predominant effect for the voltage response in each test case. The voltage response measured in the test cases was dominated either by air supply, membrane humidification or coolant temperature dynamics. This systematic comparison of different types of test setups highlights the importance of application-like system level testing as, in contrast to common experiments, different phenomena shape the electrical stack behavior.
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