The Effects of Chemical Pressurization on Screen Electrode Fuel Cells

A large amount of fuel cell research focuses on porous gas diffusion (PGD) fuel cells which currently produce the best power density. However, this sect of fuel cell technology has many obstacles to overcome before becoming a viable large scale source or power. Nevertheless, alternatives to PGD fuel cells exist. Fluidized bed electrodes (FBE), packed bed electrodes, and packed screen electrodes are discussed and analyzed in this thesis. Fluidization provides a number of benefits, but also presents a different set of obstacles. One of the largest benefits of fluidization is the possibility of using chemical pressurization to increase the reactant concentration. Perfluorocarbons (PFC), currently being used in biomedical applications as oxygen carriers in plasma, can be used to effectively raise the cathode oxygen concentration. This thesis will propose a model of perfluorocarbon emulsions as applied to an oxygen half cell. The model is first developed for the simple case of a rotating disk electrode (RDE). The predictions of this model are then compared with data obtained from a RDE experiment with and without the use of PFC's. The model is then extended to the use of packed screen electrodes. The key findings of the model include the relationships between bed length, power output, oxygen concentration, and volumetric flow rate. Finally, the thesis is concluded with a description of the setup created to test the predictions of the model and proposals for future extensions of this research. Thesis Supervisor: Ernest G. Cravalho Title: Professor of Mechanical Engineering