Maxwell-Stefan Diffusion in a Fuel Cell Unit Cell
Application ID: 247
In concentrated gases and liquids, where the concentrations of species are of the same order of magnitude, there is no obvious solvent-solute relationship. Fick’s law for diffusion accounts only for one-way solute-solvent interactions whereas the Maxwell-Stefan equations account for all interactions of species in a solution. In a system with three components, three pair-wise interactions are present, while for a system of four components there are six such interactions. These interactions are described as Fick-analogous Maxwell-Stefan diffusion coefficients.
This example models the steady-state mass transport in the cross section of a proton exchange membrane fuel cell cathode. It models the mass transport in the 3-component gas mixture by using a Concentrated Species interface including a Maxwell-Stefan diffusion model. The cross section includes the channel and current collector in the bipolar plate, at the upper boundary, while the active layer defines the lower boundary.
The purpose of this model is to show how to consider Maxwell-Stefan diffusion in mass transport.
This model is included as an example in the following products:Chemical Reaction Engineering Module
however additional products may be needed to reproduce it. This example may be created and run using components from the following product combinations:
- COMSOL Multiphysics® and
- either the Batteries & Fuel Cells Module, CFD Module, or Chemical Reaction Engineering Module and
- either the Batteries & Fuel Cells Module, Chemical Reaction Engineering Module, or Electrochemistry Module
The combination of COMSOL® products required to model your application depends on several factors and may include boundary conditions, material properties, physics interfaces, and part libraries. Particular functionality may be common to several products. To determine the right combination of products for your modeling needs, review the Specification Chart and make use of a free evaluation license. The COMSOL Sales and Support teams are available for answering any questions you may have regarding this.