Publication Date

2016

Document Type

Honors Thesis

Department

Engineering

Keywords

Proton exchange membrane fuel cells, PEM, Fuel cells, Mass transport, Gas diffusion-layer, Design, Proton exchange membrane fuel cells- Design, Proton exchange membrane fuel cells-Testing, Gas-Diffusion rate

Abstract

A proton exchange membrane fuel cell (PEMFC) is an energy conversion device that produces work through a chemical reaction between hydrogen and oxygen to produce water. Fuel cells are a potential alternative to batteries in meeting the needs of portable applications, and have the added advantage of operating on a renewable energy source that does not have to rely on fossil-fuels for recharging. In order to become a viable alternative to batteries, PEMFCs must achieve comparable specific energy and power densities (Wh/g and W/g). This thesis outlines the design and testing of a miniature two-cell PEMFC stack for application in controlled meteorological balloons (CMETs), which are a type of unmanned aerial system used for atmospheric research. Design choices regarding system architecture, material selection, and stack design were based on a single-cell stack that was previously fabricated for the same application. The stack went through an initial series of design iterations that targeted reductions in stack mass. The resulting stack was able to operate under a load, but exhibited performance degradation indicative of cathode flooding. Further design iterations focused on mitigation of cathode flooding. Following every design iteration, the stack was tested with a protocol designed to mimic in-flight test conditions, and evaluated based on stability of performance as measured through voltage response following cathode surging. The final design is able to operate in a stable manner for at least 2.5 hours with a maximum power density of 26 mW/g. Future work should continue to address the occurrence of cathode flooding to improve stack performance, and also aim to further increase specific energy and power densities through further reductions in stack mass and the addition of more cells to the stack.

Language

English

Comments

ix, 54 pages : color illustrations. Honors project, Smith College, 2016. Includes bibliographical references (page 53-54)

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