Date of Award

1-1-2009

Document Type

Campus Access Dissertation

Department

Chemical Engineering

First Advisor

Ralph E. White

Abstract

Several industrial sites are now undergoing remediation to remove toxic waste that has managed to make it into the ecosystem. One way to remediate the toxic waste is to use electrochemical reactions to convert the toxic waste into a naturally occurring non toxic species through use of a parallel plate electrochemical reactor. A model is presented for the reduction of hexavalent chromium in a parallel plate electrochemical reactor via a homogenous reaction between chromium (VI) and iron (II) generated at the iron anode. The effects of the space velocity of the feed solution, the concentration of supporting electrolyte, the distance between the electrodes, and the cell potential on conversion of chromium (VI) to chromium (III) are addressed.

While remediation addresses how to deal with waste, it would be better if the amount of waste generated was minimized. One way to generate less waste is to increase the efficiency of converting chemical energy into electricity. Solid oxide fuel cells are capable of being twice as efficient at converting chemical energy into electricity as the standard coal fired power plants. Solid oxide fuel cells (SOFCs) can convert the chemical energy stored in hydrocarbon fuels directly into electricity bypassing the multiple energy transfers that normally occur, when hydrocarbon fuels are combusted to produce electricity. CellTech Power LLC has developed a liquid tin anode (LTA) SOFC that is sulfur tolerant. A 1-D model of the LTA-SOFC is presented which includes a porous cathode and the transient terms of the material balances. The results of this work indicate that the tortuosity of the cathode and the LSM layer should be as close to unity as possible, and that the porosity of the LSM should be between 0.4 and 0.8 while the porosity of the cathode should be 0.2. Additionally, a first principles analytical impedance model of the liquid tin anode solid oxide fuel cell anode half cell is presented and used to predict critical properties of the LTA-SOFC.

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