Pressure

Question 1

What are the pros of running a high pressure FC?

Answer 1

Increased exchange current density, decreasing Vact.
Improved gas diffusion through GDL.
Overall, better stack performance.

Question 2

What are the cons of running a high pressure FC?

Answer 2

Higher parasitic loads, so net power can decrease. Therefore, need to optimise around net power output.
Need custom compressors (e.g. from Garett) which run without oil and are very expensive, and add balance of plant.
Humidifier needed to manage RH to balance pressure.
Too high pressure could drop the RH of the inlet air if not balanced.
Too low pressure will reduce performance since H+ ions won’t be able to move across membrane easily.