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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. Outline of Presentation.
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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
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
Benefits of Fuel Cell Compressors: Increased fuel efficiency Increased power density Reduced stack size Reduced cost Compressor** Fuel Cell* Compressed Air Mobile Fuel Cell (FC) Power Systems Fuel Cell Automobile* Needs of Fuel Cell Compressors: • More powerful positive-pressures • Extreme rotational speeds (~160 mph) • Oil-free lubrication *Daimler-Chrysler **http://www.mechanology.com
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 oC to ~800 oC) Shaft Bearing Fuel Cell Compressor (Courtesy Mechanology,LLC) Journal Bearing
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)
Film Transfer Experiments: Pellet-On Disk with Slider Measurables 1) Pad friction 2) Pellet friction 3) Pellet Wear • Higgs III, C.F., Ph.D Thesis, Rensselaer Polytechnic Institute, 2001 • Kaur, Higgs, and Heshmat, STLE Tribology Transactions, 2001
Contact Pressure Pc (psi) Contact Pressure Pc (psi) Past Powder Results:Friction and wear versus slider contact pressure Friction coefficient Deposition rate (cm3cm-1kg-1)
Proposed Research • Experimentation • Modeling
Experimentation: Pellet-On Disk with Slider Tribometer • Measurables: • Pad friction • Pellet friction • Pellet wear
Experimentation: Pellet-On Disk with Slider Tribometer(in construction) (Boric acid powder ) Tribometer(Photograph)
Conservation Law Control Volume Fractional Coverage (CVFC) Model Wornyoh, E.Y.A., & Higgs, C.F., III, Proceedings of World Tribology Congress III, 2005
Solution = Fractional Coverage Steady State Fractional Coverage Solving the CVFC Model Time Constant
Slider coefficient of friction Pellet coefficient of friction Adopting the Linear Rule of Mixtures Dickrell, P.L., Sawyer, W.G., and Erdemir, A., Journal of Tribology, 2004
Current and Proposed Research • Construction of tribometer • Pellet-on-disk with slider experiments • Powder lubrication modeling
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