In this paper, a new voltage aging model for the polymer electrolyte membrane fuel cell (PEMFC), which includes multiple degradation mechanisms for proton exchange membrane fuel cells, is proposed. The model parameters are identified using a curve-fitting procedure based on long-term experimental data for the modular stack under the New European Driving Cycle (NEDC). A good fit was found between the model and experimental data, with R-squared values greater than 0.99 for all simulation cases. Moreover, according to the model sensitivity analysis, the voltage degradation model is most sensitive to load current, followed by time. The effect of operating temperature on performance, voltage degradation, and lifetime is investigated. After 300 h, significant performance loss was detected. When the temperature is raised to 75 °C, voltage degradation becomes worse. Based on the simulated voltage degradation profiles at 55 °C and 75 °C, PEMFCs have reached the end of their useful lives at 1100 h and 600 h, respectively. The simulation model indicates that the model is capable of forecasting how long the fuel cell will last under specified operational conditions and drive cycles.

Maintaining the performance of a fuel cell stack requires appropriate management of water in the membrane electrode. One solution is to apply an external humidifier to the supply gases. However, the operating conditions change continuously, which significantly affects the humidifier performance and supply gas characteristics. A straightforward humidifier module is needed for integration with the fuel cell system model. In this study, a lumped-mass model was used to simulate a hollow-fiber membrane humidifier and investigate the effects of various input conditions on the humidifier performance. The lumped-mass model can account for heat transfer and vapor transport in the membrane bundle without losing simplicity. The humidifier module was divided into three parts: a heat and mass exchanger in the middle and two manifolds at the ends of the exchanger. These components were modeled separately and linked to each other according to the flow characteristics. Simulations were performed to determine the humidifier response under both steady-state and transient conditions, and water saturation was observed in the outlet manifold that may affect the humidifier performance. The findings on the effects of the operating conditions and humidifier dimensions on the cathode gas can be used to improve humidifier design and control.