Fuel Cell Electric & Hybrid Prime Movers

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. V e H2 AFC 600C 100 kW O2 OH - H2O O2 PEMFC 600C 250 kW H2 H + H2O O2 CH3OH DMFC 800C 2 MW H + H2O CO2 O2 H + PAFC 1900C 11 MW H2 H2O H2 O2 MCFC 6500C 2 MW CO32- H2O CO2 H2 SOFC 10000C 1 MW O 2- O2 H2O Fuel Oxygen Anode Cathode Electrolyte Classification of Fuel Cells based on electrolyte used 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 = 1.04445 * 10 -5 kg H2 / s - kA For 60 kW plant : I = Power / Voltage = 60000 / 0.7 = 85 kA Mass flow rate of hydrogen : Number of cells in a stack Therefore, for 60 kW, Total current = 60000 / 0.7 = 85000 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 • 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. V-I Characteristics of the Fuel cell

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 Array of cells Single cell assemble 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 Driving 60 40 20

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