EGM_3344_Course_Project

EGM_3344_Course_Project - COURSE PROJECT EGM 3344 I...

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COURSE PROJECT EGM 3344 I. BACKGROUND “A solid oxide fuel cell (SOFC) is an electrochemical conversion device that produces electricity directly from oxidizing a fuel. Fuel cells are characterized by their electrolyte material and, as the name implies, the SOFC has a solid oxide, or ceramic, electrolyte. Advantages of this class of fuel cells include high efficiencies, long term stability, fuel flexibility, low emissions, and cost. The largest disadvantage is the high operating temperature which results in longer start up times and mechanical/chemical compatibility issues.” - Wikipedia ( http://en.wikipedia.org/wiki/Solid_oxide_fuel_cell ) Researchers in the Material Science and Engineering Department at the University of Florida are investigating ways to improve electricity production using solid oxide fuel cells. These fuel cells work because of an oxygen potential difference. The electrolyte (Gadolinium doped Ceria or Yttria Stabilized Zirconia) are primarily oxygen ion conductors (minimal electronic conductivity). On the cathode side, oxygen is reduced to 2 O - and conducts to the anode where hydrogen is oxidized to form H +. At the anode, two hydrogen ions combine with one oxygen ion and the byproduct is water. The effective overall reaction is 22 2 HO H O + . One of the limiting factors in making solid oxide fuel cells feasible for commercialization is the high operating temperatures needed to activate reduction and conduction. One way to characterize the catalytic activity for oxygen reduction of a cathode material is isotope exchange over a powder sample in a continuous flow reactor. At high temperature (say 800 ºC), oxygen exchange occurs in the material. However, the rate of oxygen incorporation and the rate of oxygen release are equal when the material is equilibrated in a particular partial pressure of oxygen. It is possible to measure the rate of exchange by replacing the 16 2 O atmosphere with 18 2 O . In this way, the total oxygen concentration stays the same, but one can measure the diffusion of oxygen into the metal oxide.
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This note was uploaded on 09/05/2011 for the course EGM 3344 taught by Professor Raphaelhaftka during the Spring '09 term at University of Florida.

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EGM_3344_Course_Project - COURSE PROJECT EGM 3344 I...

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