Proton Exchange Membrane Fuel Cell, PEMFC, Stack Fuel Cell System, CFD Simulation, ANSYS Fluent Tutorial

Description

In this project, we perform the numerical simulation of a Fuel Cell Stack using ANSYS Fluent software.

This product is the 4th chapter of the Fuel Cell Training Course.

A fuel cell is an energy conversion device that converts the chemical energy of fuel into electrical energy. A fuel cell produces electricity through a chemical reaction.

Fuel cells have two electrodes called an anode and a cathode. These chemical reactions occur in these electrodes and lead to electricity production.

In addition, fuel cells have an electrolyte and a catalyst. The electrolyte layer transports charged particles (ions) between the electrodes, while the catalyst layer increases the speed of reactions in the electrode layers.

The hydrogen is fed to the fuel cell as the main fuel. However, oxygen is also required for the reaction to take place.

One of the most important advantages of the fuel cell is that electricity is produced with the least amount of pollution. Most of the oxygen and hydrogen input to the fuel cell is eventually released as a harmless product, that is, water.

There are different types of fuel cells. In this project, we have simulated the proton exchange membrane fuel cell (PEMFC).

Practically, each fuel cell produces a very low amount of current. So, We used a large number of cells in large groups called a stack to generate electricity. In a fuel cell stack, several individual fuel cell units are combined.

Methodology

We simulated this project based on the CFD method by ANSYS Fluent software.

First, we designed the geometry of the model in 3D using Design Modeler software. The computational domain of the model is related to the interior space of a fuel cell.

Then, we meshed the model using ANYS Meshing software. The meshing is unstructured, and 9046409 cells are generated.

Finally, we performed the simulation process in Fluent software.

For this simulation, we used the fuel cell model in Ansys Fluent software. The fuel cell model is an add-on module in Ansys Fluent software.

There are three different fuel cell add-on modules available in the software. We have used the fuel cell and electrolysis model. Here, there are three submodels. We have used the PEMFC model.

In the fuel cell model setting, we determine the different layers of the fuel cell. These layers include the cathode and anode layers, along with the electrolyte layer. Each of the anode and cathode layers consists of current collectors, gas diffusion layers (electrode layers), catalyst layers, and flow channels.

Since we combined several fuel cell units for this fuel cell system, we need to use the stack management option.

Since we used the fuel cell model, the species transport model is automatically activated. The species transport model defines the species present in the fuel cell, including H2, O2, and H2O.

Conclusion

After conclusion, we have obtained the contours related to electric potential, protonic potential, water content, current flux density magnitude, transfer current, and mass fraction of H2, O2, and H2O.

The H2, O2, and H2O mass fraction contours show that hydrogen enters from the anode sides, oxygen enters from the cathode sides, and water is produced in the cathode sections. This behavior is exactly according to the functional mechanism of the PEMFC fuel cell system.

When we use the fuel cell model, some user-defined scalars (UDS) are enabled. Here, we obtained the contours of electric potential (scalar 0), protonic potential (scalar 1), and water content (scalar 3). These contours show that the potential equations of the fuel cell model are solved correctly. Hence, the effect of electrons and protons in fuel cell layers is understandable. In addition, the production of water in the fuel cell is also significant.

Also, when we use the fuel cell model, several user-defined memories (UDM) are enabled. Here, we obtained contours of current flux density magnitude (user-defined memory 3) and transfer current (user-defined memory 13). These contours show that the current is generated based on the voltage we defined for the fuel cell.