Thesis Proposal and DEA Presentation

1. Thesis Proposal and DEA Presentation Attila Husar Doctoral Program of Thermal Engineering Department of Thermal Motors and Machines (MMT) Universitat Politècnica de Catalunya (UPC) September 19 2008

2. Dynamic water management of an open-cathode self-humidified PEMFC system Directors: Maria Serra i Prat Jordi Riera i Colomer Tutor: Assensi Oliva i Llena

3. Contents • Introduction to PEM fuel cell technologies • State of the art of PEM technology • Thesis objectives • Methodology • Main Contributions • Timetable • Doctoral Courses & Background • Academic Projects • Published work 3/34

4. External load Gas Diffusion Layer Gas Diffusion Layer Anode collector plate Cathode collector plate Membrane oxygen feed O2 2e- Heat 2H+ H2®2H+ + 2e- O2 + 4H+ + 4e-® 2H2O Basic PEM Fuel Cell H2O H2 Catalyst layers hydrogen feed 4/34

5. Introduction to PEM fuel cell technologies • Anode reaction • Cathode reaction • Overall reaction 5/34

6. Types of PEM fuel cell systems Ballard Nexa® 1.2 kW stationary system GM Hy-Wire® 94 kW automotive system PaxiTech® 6-15 W portable system 6/34

7. Advantages to hydrogen and fuel cells • Hydrogen as an energy carrier • Water is the product when converting H2 into electrical energy • H2 can be generated or converted to electricity relatively easily and efficiently • H2 can be stored in multiple forms: gas, liquid, metal or chemical hydrides • H2 can be transported through pipelines • H2 safety compared to other currently used energy storage media is similar • H2 has a high energy density based on mass: H2 is 120 MJ/kg, compared to natural gas which is 50 MJ/kg. • PEM fuel cells • High efficiency40-70% depending on the design and application • Run at relatively low temperature 25-80ºC • Minimal moving parts, fan/compressor and valves. • Single step process to go from fuel to electricity 7/34

8. Issues associated to the technologies • Cost • Cost needs to be reduced to compete with other energy conversion technologies • Size • The volume of the systems needs to be reduced to be viable especially for automotive and portable applications • Weight • The weight of the systems need to be reduced to be viable especially for automotive and portable applications • Durability • System need to last 5,000 hrs for automotive applications and 40,000 hrs for stationary applications • Stability • Systems need to produce stable fast responding power for most of the applications 8/34

9. Introduction to problem A majority of the previously mentioned issues can be improved through proper water management • Water balance is CRITICAL for proper operation • Simple control actions can improve water balance Why? • Water is required for conduction of protons in the membrane • Lack of water → higher resistance in membrane • Excess water → hindering of fuel and oxidant diffusion 9/34

10. State of the Art & Literature Review 10/34

11. State of the art of PEM technology Modeling approaches • Fuel cell performance models • Steady state modeling of just the fuel cell • Dynamic modeling of just the fuel cell • System models • Steady state modeling of the whole system • Dynamic modeling of the whole system 11/34

12. Fuel cell performance models Model the individual voltage losses: • Activation polarization • Ohmic losses • Concentration polarization • Internal currents and reactant gas crossover losses (generally insignificant) Approximation of the individual voltage losses and the resulting polarization curve 12/34

13. State of the art of PEM technology Water transport models • Most of the models in the literature are either based off of the ex situ experiments done by Springer 1991 and Zawodzinski 1991 or are an interpretation of their data. • Electro-osmotic drag • Ranged from 0.9 to 2.5 H2O/H+ depending on • membrane water content of 11 to 22 H2O/SO3- • temperature 30 to 50ºC • Water diffusion • The diffusivity of water through the membrane is strongly dependent on temperature • Increased from 3.5E-7 to 1.2E-6 cm2/s when temperature increased from 45 to 75ºC • Observed that the rate of water desorption will differ from the rate of absorption 13/34

14. System models Characterize each component in the model and integrate them into subsystems • Fuel supply • Air supply • Thermal management • Water management • Power management 14/34

15. Open Cathode fuel cell system Characteristics: • Open cathode • Self humidified • Simple system: • Hydrogen purge valve • Fuel cell stack short circuit • Open cathode with one fan for cooling and air supply Open cathode system schematic 15/34

16. Issues associated to open cathode systems • Influenced by environmental condition • Efficiency can be improved by modifying the control strategy • Purging the hydrogen only when needed • Initiating a short circuit only when needed • Adjusting the fuel cell temperature depending environmental conditions and fuel cell system power output H-100 Fuel Cell System from Horizon Fuel Cell Technologies, 100 Watts max. power output, 12V@8.5A 16/34

17. Objectives 17/34

18. General Objective To develop guidelines and control objectives to improve performance and stability in open cathode fuel cells Insights will be gained through: • Experimental testing • System modeling • Model of the dynamic water transport • through the membrane • membrane water content • Integrated system model 18/34

19. Specific objectives (1) Determine the effect of the operatingconditions on the fuel cell performance and stability, specifically focused on water vapor concentrations. Operating conditions: • Ambient temperature • Ambient relative humidity • Electric load 19/34

20. Specific objectives (2) Determine the effect of the three control actions on transport and water content in the membrane, and its consequences on the performance and stability, at a wide range of operating conditions. • Independent effects • Combined effects Three control actions: • Fan velocity • Hydrogen purge frequency • Short circuit frequency 20/34

21. Specific objectives (3) Model the transport of water through the membrane based on experimental identifications of the principal coefficients. • Membrane water content • Water diffusion coefficient • Electro-osmotic drag coefficient • Thermal coefficients 21/34

22. Limits to the thesis • Detailed electrochemical reaction equation will not be contemplated • Durability or system failure analysis will not be considered • A specific controller will not be designed or implemented • Power conditioning will not be developed. This is strongly dependent on the application. 22/34

23. Methodology 23/34

24. Methodology Approach: Step 1): Determine the water diffusion through the membrane as a function of temperatures and membrane resistance Step 2): Determine the electro-osmotic drag as a function of temperature, membrane resistance, and current Step 3): Incorporate water transport in a complete model including the effects of the environmental conditions Step 4): Determine the effects of the three control actions and how they can be combined to improve the performance 24/34

25. Methodology Test station design and implementation Control: • Inlet reactant parameters • Environmental parameters • Power draw Measure: • Outlet gas variables • Cell Voltages • Cell Temperatures • Membrane resistance Doctoral Courses Research work protected Thesis project Publications Other merits Doctoral Courses Research work protected Thesis project Publications Other merits 25/34

26. Methodology Test station to be built with environmental chamber 26/34

27. Methodology System Model Structure Model will include: • Cathode fan • Anode forward pressure regulator, • Anode purge valve • Membrane water content • Membrane water transport • Thermal model of stack 27/34

28. Contributions • Propose an experimental methodology to identify key physical parameter for an open cathode PEMFC • Propose a control oriented model of an open cathode PEMFC system • Propose control guidelines to improve performance and stability of an open cathode PEMFC 28/34

29. Timetable Estimated time for the individual tasks Current state 29/34

30. Doctoral Courses & Background 30/34

31. Degrees and Professional Experience • Bachelors of ScienceDegree in Mechanical Engineering at the University of Miami Coral Gables FL, USA 1992 - 1997 • Fuel cell Stack Design Team Leader at Energy Partners L.L.C in West Palm Beach FL, USA 1997 - 2001 • Masters of Science Degree in Mechanical Engineering at the University of Miami Coral Gables FL, USA 2001 - 2003 • Contracted to design and implement fuel cell laboratory at the Institut de Robòtica i Informàtica Industrial, Barcelona 2004 - 2006 • Ph.D. candidate at Universitat Politècnica de Catalunya 2006 - to present 31/34

32. Doctoral Academic Courses • Advanced heat transfer - Conduction • Advanced internal combustion engines • Finite element methods • Hydrogen Energy • Intermediate fluid mechanics • Intermediate heat transfer • Methods of engineering analysis • Numerical methods in heat and mass transfer 32/34

33. Academic projects University of Miami • Variable compression fuel cell design • Direct methanol fuel cell design • Masters Thesis: Experimental study of in situ water transfer through the membrane in a PEM fuel cell Universitat Politècnica de Catalunya • Description of gasket failure in a 7 cell PEMFC stack • Numerical Model for Polymer Electrolyte Membrane Fuel Cells with Experimental Application and Validation 33/34

34. International Publications and Patents • Fuchs M., F. Barbir, A. Husar, J. Neutzler, D.J. Nelson, M. Ogburn, Performance of Automotive Fuel Cell Stack, SEA Document Number: 2000-01-1529 (2000) • Barbir F., M. Fuchs, A. Husar, J. Neutzler, Design and Operation Characteristics of Automotive PEM Fuel Cell Stacks, Progress in Technology Series Society of Automotive Engineers, Inc (SAE), pg 139-145, (2001) • Wang L., A. Husar, H. Liu, A parametric study of PEM fuel cell performances, Inter. J. Hydrogen Energy, Vol. 28, Iss. 11, 1263-1272 (2003) • Serra M., A. Husar, D. Feroldi, J. Riera, Performance of diagonal control structures at different operating conditions for Polymer Electrolyte Membrane Fuel Cells, J. Power Sources, Vol. 158, Iss. 2, 1317-1323 (2006) • Husar A., M. Serra and C. Kunusch, Description of gasket failure in a 7 cell PEMFC stack, J. Power Sources, Vol. 169, Iss. 1, 85-91 (2007) • Alonso J., A. Husar, M. Serra, J. Riera, Numerical Model for Polymer Electrolyte Membrane Fuel Cells with Experimental Application and Validation, Asia-Pacific J. Chemical Engineering, In press (2008) • Husar A., A. Higier, and H. Liu, In situ measurements of water transport due to different mechanisms in a PEM fuel cell, J. Power Sources, Vol. 183, Iss. 1, 240-246 (2008) • Kunusch C., A. Husar, P.F. Pulestion, M.A. Mayosky, J.J. Moré, Linear identification and model adjustment of a PEM fuel cell stack, Inter. J. Hydrogen Energy, Vol. 33, Iss. 13, 3581-3587 (2008) • Patent: Neutzler J.K., F. Barbir, Y. Ngu, A. Husar, S. Rachael, FREEZE TOLERANT FUEL CELL SYSTEM AND METHOD, Pub. No. WO/2000/065676 (2000) • Patent: Barbir F., A. Husar, R.K. Wynne, J.K. Neutzler, M. Graham, H. Liu, FUEL CELL MULTI-PORT MANIFOLDING, Pub. No. WO/2001/017049 (2001) 34/34