STUDY OF A METHANOL REFORMING POLYMER ELECTROLYTE FUEL CELL SYSTEM
Open Access
- Author:
- Bhatia, Krishan Kumar
- Graduate Program:
- Mechanical Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- July 09, 2004
- Committee Members:
- Chao Yang Wang, Committee Chair/Co-Chair
Matthew M Mench, Committee Member
Daniel Connell Haworth, Committee Member
Andre Louis Boehman, Committee Member - Keywords:
- fuel cell
hybrid vehicle
reforming
CO poisoning - Abstract:
- As an alternative to on-board gaseous storage of hydrogen for fuel cell vehicles, a simple liquid hydrocarbon, such as methanol, could be stored and reformed into hydrogen as needed. However, carbon monoxide (CO), a by-product of both the on-board and off-board hydrocarbon reforming processes, is a poison to fuel cell catalysts. In addition, the size of either an on-board hydrogen storage system or hydrocarbon reforming system puts severe packaging constraints on vehicle architecture. This thesis is a comprehensive study of the effects of methanol reformate on the performance of a polymer electrolyte membrane (PEM) fuel cell. While investigating the problem of vehicle architecture constraints, it was found that humidification and pressurization of this fuel cell system can be optimized, and thus make room available on-board for either a methanol reforming/CO treatment system or hydrogen storage system. In addition, it was found that methanol reformate, which contains dilute hydrogen and trace quantities of CO, is extremely detrimental to the performance of a PEM fuel cell. Furthermore, it was discovered, both experimentally and theoretically, that the transient process of poisoning is not only a function of CO concentration, but is also highly dependent on the level of hydrogen dilution. After studying the poisoning process, an actual methanol reforming fuel cell system was integrated and tested for overall efficiency. It was found that anode air injection was capable of greatly reducing the poisoning effect. This integrated methanol reforming system was compared to a direct methanol fuel cell system at various power levels. For automotive power applications, cost constraints proved the indirect system superior to the direct methanol system. However, with a well-to-wheel efficiency of 22%, the indirect methanol system was inferior to direct hydrogen fuel cell vehicles.