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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 application was built using the following:

Chemical Reaction Engineering Module

The combination of COMSOL® products required to model your application depends on the physics interfaces that define it. Particular physics interfaces may be common to several products (see the Specification Chart for more details). To determine the right combination of products for your project, you should evaluate all of your needs in light of each product's capabilities, consultation with the COMSOL Sales and Support teams, and the use of an evaluation license.