Title page for ETD etd-01302008-170258


Type of Document Master's Thesis
Author Shevock, Bryan Wesley
URN etd-01302008-170258
Title System Level Modeling of Thermal Transients in PEMFC Systems
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Nelson, Douglas J. Committee Chair
Ellis, Michael W. Committee Member
von Spakovsky, Michael R. Committee Member
Keywords
  • Fuel Cell
  • System
  • PEMFC
  • PEM
  • Polymer Electrolyte Membrane
  • Hydrogen
Date of Defense 2007-01-28
Availability unrestricted
Abstract
Fuel cell system models are key tools for automotive fuel cell system engineers to

properly size components to meet design parameters without compromising efficiency

by over-sizing parasitic components. A transient fuel cell system level model is being

developed that includes a simplified transient thermal and parasitics model. Model

validation is achieved using a small 1.2 kW fuel cell system, due to its availability. While

this is a relatively small stack compared to a full size automotive stack, the power,

general thermal behavior, and compressor parasitics portions of the model can be

scaled to any number of cells with any size membrane area. With flexibility in

membrane size and cell numbers, this model can be easily scaled to match full

automotive stacks of any size.

The electrical model employs a generalized polarization curve to approximate system

performance and efficiency parameters needed for the other components of the model.

General parameters of a stack’s individual cells must be known to scale the stack

model. These parameters are usually known by the time system level design begins.

The thermal model relies on a lumped capacity approximation of an individual cell

system with convective cooling. From the thermal parameters calculated by the model,

a designer can effectively size thermal components to remove stack thermal loads.

The transient thermal model was found to match experimental data well. The steady

state and transient sections of the curve have good agreement during warm up and cool

down cycles.

In all, the model provides a useful tool for system level engineers in the early stages of

stack system development. The flexibility of this model will be critical for providing

engineers with the ability to look at possible solutions for their fuel cell power

requirements.

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