Application of Reactive Molecular Dynamics to Simulate Diffusion and Reaction in a Solid Oxide Fuel Cell Pore

Abstract

In a typical solid oxide fuel cell (SOFC), the kinetics of the gas phase reactions in the porous anode and electrochemical reactions at the triple phase boundary are generally unknown. Due to the unavailability of non-destructive experimental methods, factors affecting the performance of SOFC systems, especially the loss in performance due to contaminants, are usually deduced from many days of experiments. In this paper a Reactive Molecular Dynamics (ReMoDy) model based on collision theory is introduced and applied to simulate the behavior of species inside a SOFC pore. Using novel simulation methods, algorithms and visualization techniques ReMoDy has the ability to simulate chemical reactions involving tens of millions of molecules and determining the thermo-physical properties of the fluids from intermolecular energies and forces. In the current work two cases of molecular dynamics simulation inside a micro pore were analyzed. In the first case diffusion of hydrogen molecules was studied inside a 0.03125 μm3 cube. The diffusion coefficients obtained from this simulation are compared to the ones obtained using Chapman-Enskog correlations. In the second case gas phase and surface reactions were modeled for Syngas oxidation in a 1 μm3 cube representing a SOFC electrode pore. For this case detailed gas phase and surface reaction mechanisms involving 13 species and 63 reactions is included. Future studies will include the calculation of diffusion coefficients, rates of formation of different species, and comparison with published data. The results can be used for the verification of continuum models.