(65c) Mitigating Membrane Degradation for Safer and Reliable, Design and Operation of Proton Exchange Membrane Fuel Cells

Ade, N., Texas A&M University
Mondal, H. N., Mary Kay O'Connor Process Safety Center
Mannan, M. S., Texas A&M University
One of the most promising technologies for moving towards a hydrogen economy is the proton exchange membrane fuel cell (PEMFC) due to its low operating temperatures, low weight and volume, high power density and short startup time. This technology has begun to be used as in the form of fuel cell electric vehicles (FCEVs). However, a major hindrance towards making PEMFCs competitive with hydrocarbon-based combustion engines is the higher costs owing to lower durability of these systems. Specifically, the reliability of membrane exchange assembly (MEA) has been identified to be the key issue contributing towards overall lower durability of these systems. This decrease in reliability is attributed to membrane degradation leading to the overall PEFMC system degradation. Apart from contributing to decreased performance and higher cost, PEMFC degradation has been identified through fault tree analysis as one of the root causes that can lead to hydrogen leak and subsequent explosion.

The consequences resulting from hydrogen leak and explosion in a PEMFC system can be disastrous, especially from the perspective of vehicular application. Therefore, to mitigate the risk associated with explosion in PEMFC system and to achieve the required levels of performance, it is essential to study the degradation of PEMFC membrane in depth. This study deals with understanding the fundamentals of PEMFC degradation through modeling using computational fluid dynamics (CFD). More importantly, the degradation mechanism is quantitatively related to the probability of explosion of the PEMFC system using fault tree analysis. Therefore, an important inference from this study will be the design and operation alternatives for PEMFC that mitigate membrane degradation leading to improvement in both performance and safety of the system.

An interesting feature of this study will be the experimental validation of the derived conclusions from the modeling study. A small scale PEMFC system will be set up and the design and operation alternatives derived from modeling study will be validated. The experimental validation will mainly involve varying the type of membranes in the PEMFC cell, flow rates of hydrogen and oxygen gas, voltage applied and mode of operation (air or pure oxygen mode). The degradation of membranes will be achieved by externally treating them with Fenton’s reagent (at varying concentrations) and the degraded membranes will be tested in the PEMFC system as well. The effects of these variations will be measured through the current generated by the PEMFC cell.