Considerations for Fuel Cells in Aviation Applications

Question 1

Fuel Cell Sizing Considerations

Answer 1

1. Trade-off between power and efficiency: for more efficiency, more fuel and heat dissipation are needed.
2. High power operating point: it requires adequate BoP sizing
3. Power management: number of cells per stack and type of connection impacts power levels.
4. Space constraints: Depending on where FC system is located, some space limitations may apply.

Question 2

Thermal management: Important points and important points at high h

Answer 2

As T is lower it is easier, and as higher is the density, it is more efficient.

Question 3

Which are the main selected effects of mechanical force on PEFC stacks

Answer 3

1. Vibration
2. Over-compression
3. Mechanical shock (basically that the components inside the PEFC move, loosing their initial positions)

Question 4

Main requirements for the power train in aviation applications

Answer 4

1. High specific power
2. High fuel efficiency
3. Transient performance

Question 5

Main energy converter options for using Hydrogen as a fuel in aviation

Answer 5

Table Main Energy Converters

Question 6

Metrics to describe Hybrid Concepts
Names and formulas

Answer 6

1. DoH (Degree of Hybridization) = installed electric power/total installed power
2. PS (Power Split) = output power fuel cell/overall output power

Question 7

Motivations for SOFC to be hydrated with GT

Answer 7

Motivations:
1. Similar operating Temperature range
2. Fuel flexibility

Question 8

Drawbacks of SOFC - GTS Hybridization

Answer 8

1. More weight and complexity of Power Train
2. Transient limitations
3. Power density

Question 9

Different concepts of SOFC - GTs Hybridization

Answer 9

1. Serial and parallel
2. -FC topping cycle: Energy conversion in the FC occurs upstream the GT.
   - FC bottoming cycle: Energy conversion in the FC occurs downstream the GT.
3. • Direct Hybrid Cycle: GT and FC are coupled.
   • Indirect Hybrid Cycle: GT and FC are decoupled.

Question 10

Different possibilities of Hybridization

Answer 10

1. SOFC - GTs
2. PEFC - Battery

Question 11

Motivation for PEFC + Battery Hybridization
Properties

Answer 11

Motivations:
1. PEFC can cover most of the power profile
2. Battery for peak power and transient loads

Properties:
1. Excellent transient performance
2. High efficiency
3. Limited power and energy density

Question 12

Different uses of PEFC - Battery Hybridization

Answer 12

1. Road transport
   Optimizing criteria: System cost and durability
2. VTOLs
   Very high peak power demand during take-off and landing
3. Regional aircraft
   Main drivers: Optimized gravimetric and volumetric power density of power train