Short Questions Flashcards
Consider an electrochemical cell with no metal electrodes. Assuming the reaction proceeds spontaneously, which will be the metal that is oxidezed?
The one with the more negative standard potential
Does a polymer electrolyte membrane conduct electrones?
No, it just allows ions to go through it
Does a bipolar plate conduct electrones?
Yes
What is the heaviest part of a PEFC cell?
By far it is the bipolar plate
Why is it important to think about the water removal/management in a PEFC to ensure high efficiency?
Water management in a PEFC is crucial to maintain optimal hydration of the membrane, prevent flooding, and ensure efficient gas flow. Proper water removal helps avoid performance loss, overheating, and component degradation, ensuring high efficiency and longevity of the fuel cell.
What is the most mature cell type of SOFCs?
Tabular
Why do ceramic fuel cells operate at high temperature?
For sufficient ion conductivity
What are typical layer thickness in state-of-the-art SOFC cells?
10s-100s micrometers
Could you name 2 advantages and 2 disadvantages of ceramic electrolytes over other electrolyte types?
Advantages:
1. High Temperature Stability: Suitable for high-efficiency applications
2. Chemical Durability: Resistant to chemical degradation
Disadvantages:
1. Fragility: Can crack under mechanical stress
2. High Operating Temperature: They require additional energy for heating and can cause material degradation
Is the need for gas compression in an aviation application of a fuel cell different form road transport application?
Yes. Because we are changing altitude and then the inlet pressure is different. In the aviation we need toadapttothat
Explain different considerations in sizing a fuel cell electric power train
- Trade-off between power and efficiency
- High power Operating Point
- Power management: How we connect the Fuel Cells between them…
- Space constraints
What are motivators for hybridizing an SOFC with a GT?
What is not?
Motivators:
1. They operate in the same Temperature range
2. Fuel flexibility
NOT motivators?
1. The system would be more complex and heavier
2. Transient performance limited
What is typically the key reason for integrating batteries in fuel cell electric power train?
Delivering additional power
What is the main reason for designing LH2 tanks in spherical or cylindrical shapes?
Surface-to-volume ratio
When comparing batteries, hydrogen and liquid hydrocarbons, what has the highest round trip efficiency of electricity storage?
Batteries
Could rerouting potentially be a viable contributor to reducing aviation’s emission?
Yes
What is not necessarily needed for a reaction to take place in an electrochemical cell?
Power source (Electricity)
Does the Nernst equation accurately describe a cell’s voltage in the application environment?
No. It is theoretical, but it just gives us an idea
Which loss terms refers (among other things) to limitations of charge transfer through the electrolyte?
Ohmic losses
Which loss term can be improved using better catalysts?
Activation losses
What function generally describes a polarization curve best?
Combination of different ones
