1. Self-replenishing, Self-repairing Solid Lubrication Technology for Fuel Cells Emmanuel Y.A. Wornyoh and C. Fred Higgs III Particle Flow and Tribology Laboratory Mechanical Engineering Dowd/ICES Seminar October 21, 2005

2. Outline of Presentation  Need for new compressor technology in fuel cells  Oil-free, self-replenishing lubrication  Proposed Research: Developing oil-free, self-replenishing lubrication for compressor

3. Mobile Fuel Cell (FC) Power Systems Benefits of Fuel Cell Compressors:  Increased fuel efficiency  Increased power density  Reduced stack size  Reduced cost Compressed Air Compressor ** Fuel Cell * Fuel Cell Automobile * * Daimler-Chrysler **http://www.mechanology.com Needs of Fuel Cell Compressors:  More powerful positive-pressures  Extreme rotational speeds (~160 mph)  Oil-free lubrication

4. Lubrication Mechanism for Fuel Cell Compressor Motivation  Energy efficiency  Replacing oil lubricants with powder lubricants  Freeing depleting global oil supplies  Environmental concerns  Testing “green” lubricants  Tribological Advantages  Stability, sustainability in extreme environments (-100 o C to ~800 o C) Shaft Bearing Fuel Cell Compressor (Courtesy Mechanology,LLC) Journal Bearing

5. Problem Statement  Need for a novel lubrication system for fuel cell compressors  Oil-free lubrication to avoid fuel cell stacks contamination  Lubrication must be adequate at extreme speeds (~160mph) and high loads Proposed Method  Design and construction of tribometer  Conduct experiments  Development of the powder lubrication (CVFC) model  Predicts tribological parameters (e.g., friction and wear)

6. Film Transfer Experiments: Pellet-On Disk with Slider Higgs III, C.F., Ph.D Thesis, Rensselaer Polytechnic Institute, 2001 Kaur, Higgs, and Heshmat, STLE Tribology Transactions, 2001 Measurables 1) Pad friction 2) Pellet friction 3) Pellet Wear

7. Contact Pressure P c (psi) Past Powder Results: Friction and wear versus slider contact pressure Deposition rate (cm 3 cm -1 kg -1 ) Friction coefficient

8. Proposed Research  Experimentation  Modeling

9. Experimentation: Pellet-On Disk with Slider Tribometer Measurables: 1)Pad friction 2)Pellet friction 3)Pellet wear

10. Experimentation: Pellet-On Disk with Slider Tribometer (in construction) Tribometer (Photograph) (Boric acid powder )

11. Control Volume Fractional Coverage (CVFC) Model Wornyoh, E.Y.A., & Higgs, C.F., III, Proceedings of World Tribology Congress III, 2005 Conservation Law

12. Solving the CVFC Model Time Constant Solution = Fractional Coverage Steady State Fractional Coverage

13. Adopting the Linear Rule of Mixtures Dickrell, P.L., Sawyer, W.G., and Erdemir, A., Journal of Tribology, 2004 Pellet coefficient of friction Slider coefficient of friction

14. Current and Proposed Research  Construction of tribometer  Pellet-on-disk with slider experiments  Powder lubrication modeling

15. Acknowledgements  The Dowd/ICES PhD fund at CMU  The Pennsylvania Infrastructure for Technological Innovation (PITA)  Mechanical Engineering Machine Shop  Members of the Particle Flow & Tribology Laboratory