Real-Time Capable Transient H₂Partial Pressure Model for Proton Exchange Membrane Fuel Cell Systems

Fuel cell electric vehicles hold a significant promise for reducing the carbon footprint in the automotive sector by leveraging H2 as a clean fuel source. Maintaining a consistent H2 supply to the fuel cell system is vital. N2 crossover can lead to an inert gas built-up on the H2 supply side, adversely affecting fuel cell performance and durability. Through purging, gases are released, and a N2 built-up in the H2 supply system can be prevented, yet this also leads to fuel loss. This fuel loss can be minimized by keeping an optimal N2 molar fraction. We developed a dynamic model for effectively designing, controlling, and diagnosing fuel cell systems by predicting the N2 molar fraction in the H2 supply. This model considers factors such as N2 distribution throughout the fuel cell stack, N2 crossover, and the purge process. The model is simplified to a differential equation of first order and solved using the explicit Euler method at a typical automotive time step of 0.01s. The proposed model is validated by a H2 measurement in a fuel cell system with passive recirculation.