Abstract

As supplies of petroleum and natural gas are constrained in many regions, and the emissions associated with fossil fuel combustion appear to be strongly connected to climate change, the development of renewable energy systems has become one of the urgent research directions. Fuel cells, with extremely low CO2 emissions, high energy density, efficiency and reliability, are now being considered as one of the most important alternatives to fossil fuel-based energy systems. In the field of new power sources for automotive, portable and residential applications, proton exchange membrane fuel cells (PEMFCs) have gained more attention in the last decade due to their high energy density, low emission generation, and relatively low temperature operation that enables rapid start-up.

Despite the many advantages of PEM fuel cells, one of their significant shortcomings is the requirement of a very pure hydrogen supply, wherein the concentration of carbon monoxide (CO) is less than 10 parts per million. An alternative technology, the so-called high temperature proton exchange membrane fuel cell (HT-PEMFC) uses an alternative membrane material that enables higher temperature operation and thus minimizes the impact of CO poisoning of the electrochemically active components. Key operational parameters, such as temperature, pressure, anode dilution (N2 and CO), start-up and shut-down processes were studied in this thesis as they are critical to fuel cell performance and need to be comprehended to support deployment in real-world applications. The system simulated in this empirical study was an HT-PEMFC integrated with a propane catalytic partial oxidation (cPOx) reformer that may be suitable for mobile applications. The HT-PEMPC was supplied with simulated cPOx reformate comprised of 49% nitrogen, 28% hydrogen and 23% carbon monoxide. The results indicate that pressure is the critical factor in controlling fuel cell performance, and potentially enhancing durability at relatively high cell temperature that minimizes voltage loss due to CO poisoning. A start-up procedure involving changes in cross-MEA pressure gradient (ΔP) was found to be beneficial to the HT-PEM fuel cell power output. It was additionally found that up to 20% nitrogen dilution in anode did not significantly affect fuel cell performance. While fueling with simulated propane cPOx reformate, the HT-PEMFC performed well for more than 200 hours, indicating that the potential exists for durable operation with judicious selection of cell operating conditions. This effort has shown that HT-PEM fuel cells with an integrated propane reforming system has enormous potential in mobile applications such as unmanned aerial systems.

Publication Date

4-2019

Document Type

Thesis

Student Type

Graduate

Degree Name

Sustainable Systems (MS)

Department, Program, or Center

Sustainability (GIS)

Advisor

Thomas Trabold

Advisor/Committee Member

Nabil Z. Nasr

Campus

RIT – Main Campus

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