Time-dependent Carbon Monoxide Effect on PEM Single Cell Anode Performance - A Numerical Modeling Study

The objective of this investigation is to gain a better understanding of how the transients in Re CO concentration in the fuel influence the response of a proton exchange membrane fuel cell (PEMFC) anode. A mathematical model has bean developed in order to study the effect of heterogeneous processes, namely, the catalytic carbon monoxide (CO) adsorption, and the dissociative chemisorption of hydrogen (HZ) on platinum (R), and subsequently their electreoxidation reactions, and their coupling with the fluid flow, on mass and energy fluxes between gas and solid phases in the PEMFC anode. The time-dependent species distribution within the entire PEMFC anode structure and the two-dimensional laminar flow fields in the single anode channels were simulated. The model of the electro-calytic reactions on the active sites of the anode accounts for a time-varying surface coverage of adsorbed species in terms of adsorption, desorption and electo-oxidation rate. A well-accepted multi-step heterogeneous reaction mechanism is used (Springer, T.E. et at., J. Electrochem. Soc. 148 (11) (2001) A11- A23). The surface coverage with adsorbed species is calculated as function of space and time, and the numerically predicted flow field, species mass fractions, potential and current density fields agree well with published experimentally determined data. The developed code is shown to be able to describe the transient behavior of the catalytic CO poisoning on Pt, thus leading to a better understanding of the intrinsic chemical reactions and their interaction with momentum, mass and heat transport in the PEMFC anode. A significant performance drop is predicted when a H2- ppm CO fuel mixture is used in comparison to pure Hz. The lower performance is due to CO adsorption on the Pt catalyst surface, lowering thus the HZ oxidation.

TSOTRIDIS Georgios; 

PODIAS Andreas; 

2009-01-27

ELSEVIER

JRC33887

https://publications.jrc.ec.europa.eu/repository/handle/JRC33887,