Dynamic operational conditions

Kurzfassung

The dynamics of proton-exchange membrane fuel cells (PEMFCs) are taking place in different time and spatial scales. First, the processes at the cell level are described, namely, double-layer charging, charge transfer, and mass transport. In addition, transients associated with humidification of membranes and catalyst poisoning are examined. At the stack level, heat transfer and gas distribution determine the dynamics of single cells and the consequences for the stack dynamic are considered. The system level encounters transient limitations due to different subsystems, in particular, the fuel supply, the air supply, the heat management, and the control of the system. The methods to measure and determine dynamic processes on the different levels (from fundamental processes to system operation) are described and corresponding component development methodology are introduced. Finally, selected experimental examples for different dynamic behaviors and measurements on all scales are presented.