Transient evolution of carbon monoxide poisoning effect of PBI membrane fuel cells

Abstract

High temperature poly benzimidazole membrane fuel cells are the focus of attention due to high CO tolerance and overcoming water managements. This paper develops a transient. one-dimensional mathematical model to predict CO tolerance, and validates it with experiments. Experimental results are measured at different temperatures. Fuel cell performance degradations with time are also measured under various fuel compositions. Transient evolutions of current density, H-2 coverage, CO coverage, and ionic potential are shown during the CO poisoning process. The theoretical results show that hydrogen coverage decreases with time, reducing hydrogen oxidation reactions and dropping ionic potential loss. The effects of temperature. CO contents. and H-2 dilutions on fuel cell performance and the time to reach steady t(ss) are all investigated. Predictions of fuel cell current density degradation also show good agreement with experimental results. (c) 2007 Elsevier B.V. All rights reserved.