1. Fuel Cell Electric & Hybrid Prime Movers
P M V Subbarao
Professor
Mechanical Engineering Department
The Most Sustainable Artificial Horse.....

2. Flow diagram for a fuel cell system

3. Fuel Cell Technologies
There are six major types of fuel cells depending on the type of their electrolyte.
Proton exchange membrane (PEM) or Polymer exchange membrane fuel cells (PEMFCs)
Alkaline fuel cells (AFCs)
Phosphoric acid fuel cells (PAFCs)
Molten carbonate fuel cells (MCFCs),
Solid oxide fuel cells (SOFCs)
Direct methanol fuel cells (DMFCs)

4. Classification of Fuel Cells based on electrolyte usedV
AFC
PEMFC
PAFC
MCFC
SOFC H2
OH -
Fuel
H2O
H +
DMFC
O 2-
CO3 2-
600C kW
600C kW
1900C MW
6500C 2 MW
10000C 1 MW
800C 2 MW O2
CO2
CH3OH
Anode
Electrolyte
Cathode
Oxygen e
Max attained
production

5. Ideal Cell Voltage
If the system is reversible (or has no losses), then this electrical work done will be equal to the Gibbs free energy released.
This fundamental equation gives the electromotive force (EMF) or reversible open circuit voltage of the hydrogen fuel cell.
In practice the voltage would be lower than this because of the voltage drops in the circuit elements.
Some of the irreversibilities apply a little even when no current is drawn, so even the OCV of a fuel cell will usually be lower.

6. Fuel flow rate calculation
For every molecule of hydrogen (H2), two electrons are Liberated.
MH2 = * kg H2 / s - kA
For 60 kW plant : I = Power / Voltage = / 0.7 = 85 kA
Mass flow rate of hydrogen :
Number of cells in a stack
Therefore, for 60 kW,
Total current = / 0.7 = amps
Required area of the cell = Total current / Current density
No. of cells = required area / area of the individual cell

7. Limit on Size of A Single Cell : Limited by Irreversibilities
Actual potential of the cell is less than the equilibrium potential due to irreversible losses or polarization.
Losses or polarizations limits Actual Performance
V-I Characteristics of the Fuel cell
Activation over potential (Vact)
Flow of ions should overcome the electronic barrier.
Ohmic over potential (Vohm)
Resistance offered by the total cell components to the flow.
Concentration over potential (Vcon)
Gas transport losses, dilution of fuel as the reactions progress.

8. Testing of A hydrogen–air fuel cell system

9. Performance characteristics of a single SOFC Cell

10. The influence of temperature on the operating voltage of different fuel cells
SOFC

11. Single cell - dismantle view
Cathode
( LSM –YSZ )
Interconnects
( Electro ceramic family )
Anode
( Ni-YSZ )
Electrolyte
( YSZ )
Seals

12. SOFC Stack assembly
Individual fuel cells must be combined to produce appreciable voltage levels
Single cell assemble
Array of cells
Stack assemble
Array of cells with insulation plate

13. Tubular Solid Oxide Fuel Cell
Interconnection
Electrolyte
Fuel flow
Air electrode
Airflow
Fuel electrode

14. Hardware Configuration of a typical fuel cell Drive
brake pedal
accelerator pedal
vehicle controller
peaking
power sound
6: electronic interface;
7: motor controller;
8: traction motor;
9: transmission;
10: wheels.

15. Performance of Fuel Cell-alone-powered Drive Train : City Driving20 40 60

16. Configuration of a typical fuel cell Hybrid Drive
Battery
Regenerative Brake

17. Flow chart of the control strategy

18. Performance of Fuel Cell-Hybrid-powered Drive Train : City Driving

19. Optimal Operation