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PEM Fuel cell Model. Error: Cant not remove trace gas (at cathode)

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I am trying to simulalate with this PEM fuel cell model the behaivoir of the PEM fuel cell at high altitude enviroment conditions (less pressure and less temperature). When I change enviroment pressure value from 0.1 to 0.07MPa:
I get the following error: Cannot remove trace gas when trace gas mass fraction of moist air volume is zero. The assertion comes from: Block path: PEM_fuel_cell/Cathode Gas Channels/Pipe (MA)1
It seems that there is no reaching oxiget at cathode channels:
But I really dont know why is happening this issue, as there is a compressor at cathode side. Is somebody could help to me how I can do to modify the model to be able to simulate this change at enviroment conditions I will be really greateful. Thanks in advance.
Best regards.

Answers (1)

Prateekshya on 18 Jan 2024
Hello Ruben,
It appears you're working with a PEM fuel cell model in a simulation environment like MATLAB/Simulink, and you're encountering issues when attempting to simulate the behavior of the fuel cell under high-altitude conditions, particularly with reduced pressure and temperature.
The error message you're receiving suggests that the simulation is trying to remove a trace gas from a mixture where the trace gas mass fraction is already zero. This could be due to the lower ambient pressure at high altitudes, which affects the partial pressure of oxygen and thus the amount of oxygen available to the cathode.
Here are some steps you might consider to troubleshoot and modify the model:
Ensure that the compressor in the cathode side is configured correctly to compensate for the lower ambient pressure. It might need to be adjusted to provide the necessary pressure increase to maintain adequate oxygen flow. Review all boundary conditions and initial conditions related to the environment, such as pressure and temperature. Ensure that they are set correctly for high-altitude conditions. Investigate where in the model the trace gas (presumably oxygen) mass fraction is being calculated or set. You might need to adjust these calculations to ensure that the mass fraction does not reach zero. Look through the entire air supply path, including any pipes, valves, and controllers, to ensure that there are no blockages or incorrect settings that would prevent oxygen from reaching the cathode channels.
If your model uses fixed-step solvers, try switching to a variable-step solver to see if it helps with the stability of the simulation under these new conditions. High-altitude conditions could require different sizing for components such as the compressor, heat exchangers, or humidifiers. Make sure these components are sized appropriately for the conditions you're simulating. Modify the model to handle cases where the oxygen mass fraction might be low. This could involve setting minimum thresholds or implementing control logic to avoid the simulation trying to remove non-existent trace gases.
I hope this helps!


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