Dissertation
Mathematical Studies of the Electric Double Layer in Electrochemical Cells with an Emphasis on Laminar Flow Fuel Cells
Doctor of Philosophy (PhD), Washington State University
01/2011
Handle:
https://hdl.handle.net/2376/117767
Abstract
The global demand for power is increasing rapidly and new advances in energy technology are required for the continued progress of humanity. Fuel cells are expected to play an important role in satisfying this need for clean and efficient energy in the near future. The purpose of this work is to investigate the fundamental phenomenon of the electric double layer (EDL) and its role in electrode kinetics as associated with fuel cell technology.
To accomplish this, a mathematical model is developed to analyze the behavior of electrode kinetics in the presence of the EDL. The model is formulated around the Poisson-Nernst-Planck (PNP) equations for the electrolyte description, with the inclusion of advection. For the Frumkin corrected electrode kinetics the generalized-Frumkin-Butler-Volmer (gFBV) equation is used. The fluid velocity field is described with the Navier-Stokes equations. This formulation is necessary for the inclusion of the EDL, which occurs at the electrode-electrolyte interface, and allows for the explicit description of ionic transport throughout the electrolyte phase. However, the underlying physics result in a strongly coupled system of equations with highly nonlinear boundary effects, causing difficulties in obtaining solutions.
In this work two solution methods are developed to perform multidimensional analysis of the electrochemical model in the context of a laminar flow fuel cell; a custom numerical simulation and a depth averaged approximate analytic solution. Both solution methods produce results that are consistent between them and are validated against published one dimensional results.
Using the techniques developed in this work the underlying physics of the EDL in laminar flow fuel cells are studied in different scenarios including the response to electrode length and separation, in the presence of reactant crossover, for acidic versus alkaline media, and in the presence of changing electrode kinetics and reactant transport. Finally, a method for improving electrode kinetics based on EDL manipulation through electrolyte advection in a nano-pore is studied along with a novel fuel cell configuration to capitalize on the enhanced performance.
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Details
- Title
- Mathematical Studies of the Electric Double Layer in Electrochemical Cells with an Emphasis on Laminar Flow Fuel Cells
- Creators
- Isaac Sprague
- Contributors
- Prashanta Dutta (Advisor)Jow-Lian Ding (Committee Member)Su Ha (Committee Member)Konstantin Matveev (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 209
- Identifiers
- 99900581752401842
- Language
- English
- Resource Type
- Dissertation