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The performance of fluidized beds, packed beds, and screens as fuel cell electrodes

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dc.contributor.advisor Ernest G. Cravalho. en_US
dc.contributor.author Ruflin, Justin, 1981- en_US
dc.contributor.other Massachusetts Institute of Technology. Dept. of Mechanical Engineering. en_US
dc.date.accessioned 2007-01-10T16:54:10Z
dc.date.available 2007-01-10T16:54:10Z
dc.date.copyright 2006 en_US
dc.date.issued 2006 en_US
dc.identifier.uri http://hdl.handle.net/1721.1/35638
dc.description Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006. en_US
dc.description Includes bibliographical references (leaves 74-75). en_US
dc.description.abstract At present, most fuel cells employ porous gas diffusion (PGD) electrodes. Although much effort has been spent on their development, the performance and cost of PGD electrodes are still major obstacles to the successful commercialization of fuel cells. As a means to bypass the drawbacks associated with PGD electrodes, several researchers have taken an alternative approach to electrode design by considering fluidized bed electrodes (FBEs), a type of flooded electrode that relies on convective rather than diffusive mass transport. Several reviews and past studies claim that FBEs have the potential for reaching high power density at a low cost due to several inherent advantages. However, the results so far of fluidized bed electrodes applied to fuel cells have been poor, and the past studies have not offered effective explanations for the discrepancy between expected and actual performance. A fluidized bed electrode model has been developed and applied to the data obtained by previous researchers in order to explain the poor performance of these past designs. As points of comparison, models have also been developed to predict the performance of packed bed electrodes and screen electrodes (two other flooded electrode designs). en_US
dc.description.abstract (cont.) Separate models have been developed to consider both ionic and mass transport. Upper bounds on the performance of all three electrodes have been established, and then compared to the performance of PGD electrodes. The results of the models indicate that the PGD electrodes perform better than the packed bed or screen electrodes by at least a factor of two, unless the flooded electrodes are very short (on the order of millimeters). Both mass transfer and the saturation concentration of oxygen in the electrolyte serve as limitations in the flooded designs. The models also indicate that the two-phase and three-phase FBEs are inferior to the other flooded electrodes. The paper concludes with several recommendations for further work, including methods to boost performance. en_US
dc.description.statementofresponsibility by Justin Ruflin. en_US
dc.format.extent 75 leaves en_US
dc.format.extent 4931223 bytes
dc.format.extent 4934293 bytes
dc.format.mimetype application/pdf
dc.format.mimetype application/pdf
dc.language.iso eng en_US
dc.publisher Massachusetts Institute of Technology en_US
dc.rights M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. en_US
dc.rights.uri http://dspace.mit.edu/handle/1721.1/7582
dc.subject Mechanical Engineering. en_US
dc.title The performance of fluidized beds, packed beds, and screens as fuel cell electrodes en_US
dc.type Thesis en_US
dc.description.degree S.M. en_US
dc.contributor.department Massachusetts Institute of Technology. Dept. of Mechanical Engineering. en_US
dc.identifier.oclc 76701807 en_US


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