M.A.P.L.E. Lab
PEFC ModelThis page provides Maple codes for the model described in the paper T. E. Springer, T. A. Zawodzinski, and S. Gottesfeld, J. Electrochem. Soc., 138, 2334 (1991). Springer, et al. describe a model of a polymer electrolyte fuel cell, as well as a method to solve it in detail. This model accounts for the transport of hydrogen in the anode and oxygen in the cathode, in addition to the transport of water through the electrodes and the separator membrane. This is very important, as the drying of the membrane is detrimental to the fuel cell performance by increasing the ionic resistance.This model assumes the incoming gas streams are saturated with water to minimize drying. They also treated the gas composition as uniform in the anode and cathode channels to simplify the model. The effect of water content on membrane conductivity and diffusivity is also considered. The file PEFCM_New_CubicDLam uses the cubic approximation given in Eq. 22 of the paper for the corrected diffusion coefficient, Dλ , across the entire domain of the water content, λ. The paper uses this approximation only for water content greater than 4 molecules/site, while using tabular values (not given) for values of water content less than 4 molecules/site. Using the the cubic approximation allows for a more robust code that is less sensitive to the initial guess provided by the user for α, as well as eliminating the need to estimate D' from Figure 3 for low values of water content. The file PEFCM_New_ComboDLam attempts to approximate D' as a linear function by using Figure 3 for low values of water content. An Arrhenius term was incorporated to extend the model to temperatures greater than 30°C. However, this method is very sensitive to the initial guess, so an initial guess is supplied by using the cubic approximation for the entire domain. This typical only provides a small correction to the cubic approximation solution. Unfortunately, this method fails when nearly maximum current is drawn. Better solvers/ initial conditions are needed at higher rates for convergence. Please feel free to contact Dr. Venkat Subramanian for any comments. List of other models:
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