2006 - 2007 Florida Solar Energy Center Research Competition
Principal Investigator: Mark R. Archambault, Ph.D. Academic Unit: Department of Mechanical and Aerospace Engineering Florida Institute of Technology Co-Principal Investigator(s): (including academic unit or affiliation) FSEC Contacts/Collaborators: Title of Proposal: Performance Evaluation of a Cylindrical PEM Fuel Cell
(Keywords: PEM Fuel Cell; Hydrogen; Alternative Fuels) Amount of Proposal: $25,000
Typed/Printed Name Principal Investigator: Dr. Mark R. Archambault
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Date Signed
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Department Head: Dr. Paavo Sepri
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Dean: Dr. Thomas D. Waite
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PERFORMANCE EVALUATION OF A CYLINDRICAL PEM FUEL CELL
Dr. M. R. Archambault Department of Mechanical and Aerospace Engineering Florida Institute of Technology
With the ever-increasing worldwide demand for energy and the steepening costs of conventional fuels, the need to find new energy sources is becoming more imperative. Proton Exchange Membrane (PEM) fuel cells are perceived to be a promising and upcoming source of alternative energy due to their adaptability and low-temperature characteristics. Already they are being studied for and used in automotive applications, space exploration and research missions, and backup and normal-usage electrical power supplies. Significant research is being conducted to increase their performance and power-to-weight ratios. Much attention has been focused on advancing the models that describe the transport phenomena and electrochemistry within the membrane electrode assembly, as well as on the materials that comprise the membrane, catalyst, and gas diffusion layers. However, comparatively less research has been undertaken to study the impact of the flow phenomena on fuel cell efficiency. The most common channel geometry for PEM fuel cells is a single-channel serpentine with a square or rectangular cross-section. However, this configuration suffers from significant pressure losses, especially in the tight channel bends. In addition, partly to mitigate these
pressure losses and in part due to manufacturing costs, the channels do not fully cover the electrode assembly area, which represents a loss of performance. Previous work has shown that by considering a range of geometric parameters such as channel cross-sectional area, aspect ratio, channel width, and gap width, performance can be optimized. The purpose of this work is to investigate a cylindrical fuel cell design. A cylindrical configuration addresses these drawbacks in the sense that (for channel dimensions sufficiently smaller than the cylinder diameter) this design does not have the tight channel bends that contribute to performance losses while covering nearly the entire area of the electrode assembly. By reducing the pressure losses in the flow and maximizing the coverage of the electrode assembly area, the amount of the fuel’s energy converted to a usable form can theoretically be increased.
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Objectives and Approach:
The primary objectives of this work are: • Compare the performance of a cylindrical PEM fuel cell to that of a conventional flat-plate cell • Identify flow path design considerations that affect the performance of a cylindrical fuel cell. Specifically, what design considerations maximize current density and thermal control • Recommend design specifications based upon findings.
The approach to this work will begin by developing a three-dimensional numerical model for a conventional flat-plate PEM fuel cell with a single serpentine channel on both the anode and cathode sides. This will provide the foundation for a base-case wherein operational and geometrical parameters will be identified such as cell voltage, hydrogen and oxygen mass flow rates, inlet temperature, humidity, etc. The fuel cell will be simulated using the Fluent
computational fluid dynamics (CFD) software with the accompanying add-on module designed specifically to examine PEM and Solid Oxide fuel cells, accounting for the electrochemistry and water transport. It will be important to obtain critical information such as current density; hydrogen consumption; and species, temperature, and pressure profiles. performance losses in the flow channels are greatest will also be identified. Once the base-case has been examined, a three-dimensional computational model for a cylindrical fuel cell will be developed. Preliminary schematic diagrams of the model are Regions where
presented in Figures 1 and 2. This initial model will serve as a starting point in the analysis. Using the same operating parameters as for the flat-plate cell, the cylindrical cell will be simulated and analyzed in a manner similar to the base-case. Incremental changes to the
cylindrical geometry will then be incorporated to determine an optimal design. Modifications to the channel cross-sectional shape and dimensions, coil pitch, and channel-gap width will all be investigated. It is expected that by addressing the areas that are responsible for performance
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losses, a cylindrical configuration will provide a greater power density than will a flat-plate fuel cell operating under similar conditions.
Follow-on
The next logical step for this project is to demonstrate the capability of a cylindrical PEM fuel cell. This can be accomplished at Florida Tech using existing fuel cell testing facilities While the numerical models
belonging the National Center for Hydrogen Research.
incorporated in the Fluent software have proven to be reliable, it will still be important to experimentally verify the computational results obtained in this study. To that end, a cylindrical PEM fuel cell can be built, and an experimental plan developed to prove the concept. The total cost for all materials and personnel necessary to complete this experimental program is in excess of the grant funds available through the present solicitation. For this reason, the principal investigator intends to submit a subsequent proposal to the Florida Hydrogen Initiative, Inc. (FHI) for the purposes of expanding upon the project described herein. Money granted by FSEC will be used as matching funds in support of the FHI proposal.
Estimated Budget: Graduate Student Support (tuition) Graduate Student Support (stipend) Faculty Summer Salary Fringe Benefits @ 26.3% Travel to 1 technical conference (faculty and student) Misc. Supplies $3000 $750 $8100 $4991 $6460 $1699
Revised Budget: $7200 $3510 $3200 $841.60
$0 $248.40
Total (Grant Request)
$25000
$15000 (Amount Received)
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Figure 1 Cylindrical Fuel Cell
Cathode (O2/Air) Channels
Cathode Gas Diffusion Layer
Cathode Catalyst Layer
Proton Exchange Membrane
Anode (H2) Channels
Anode Gas Diffusion Layer
Anode Catalyst Layer
Figure 2 Schematic of Cylindrical PEM Fuel Cell
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