Performance of an energy-efficient multi-stack PEM fuel cell system with optimized oxygen excess ratio

The increasing concerns over global warming resulting from transportation systems have spurred the automotive industry to shift towards green technologies. In recent years, the consideration of hydrogen fuel cell vehicles has gained considerable importance due to their high energy density, fast refuelling, and zero local emissions. Road freight vehicles contribute significantly to overall emissions, making them a strategic target for sustainable technological progress. Hybrid multi-stack proton exchange membrane (PEM) fuel cell systems with a battery can strategically provide fast refuelling and high-power demand for this application. The gaseous supply to the fuel cell accounts for most of the parasitic power consumption of the balance of plant. This works explores the performance of an energy-efficient PEM fuel cell system with an optimized oxygen excess ratio (OER). At one extreme, oxygen starvation degrades the fuel cell. However, at the other extreme, the additional power required by the compressor will eventually reduce the system's net power. The increased fuel cell energy production and increased parasitic load of the compressor are both nonlinear. Thus, the energy-efficient OER must be carefully tuned to maximize the fuel cell system efficiency. The efficiency map will be presented along with the system (fuel cell, battery, compressor, humidifier, heat exchanger, DC/DC converter, etc.) simulation following the driving cycle.