Potential of Proton-Exchange Membrane Fuel-Cell System with On-Board O2-Enriched Air Generation

Abstract

Hydrogen fuel-cell systems are one of the alternatives for the decarbonization of the transportation sector. In such systems, the usage of O (Formula presented.) -enriched air has the potential to improve fuel cell performance as well as to reduce degradation phenomena linked to local O (Formula presented.) starvation. However, the production of an O (Formula presented.) -enriched air stream implies energy consumption that needs to be evaluated in the overall system efficiency. In this study, the potential of a system including polymeric membranes for O (Formula presented.) -N (Formula presented.) separation to produce O (Formula presented.) -enriched air was evaluated theoretically. First, the balance of plant, including the O (Formula presented.) -N (Formula presented.) separation membrane and a two-stage boosting system, was considered. Two sources of energy recovery were identified: a high-pressure H (Formula presented.) stream and retentate flow (N (Formula presented.) -rich) at the outlet of the separation membrane. Then, the efficiency of the system was evaluated for different levels of O (Formula presented.) enrichment, with sensitivities to the main operational and design parameters, i.e., cathode excess O (Formula presented.) ratio, turbomachinery efficiency, essure ratios. The results show the potential for an O (Formula presented.) -enriched system if the energy recovered reaches approximately 25% of the additional power consumption induced by the separation membrane.