Design Of Fuel Cell Membrane Test Stand

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  • Semipermeable membrane
  • Luke
  • Design Of Fuel Cell Membrane Test Stand

    1. 1. Design of Fuel Cell Membrane Test Stand for Advanced Fuel Cell Research<br />Rebekah Achtenberg, Brandon Darr, Luke Roobol<br />Western Michigan University<br />College of Engineering and Applied Sciences<br />Mechanical and Aeronautical Engineering Department<br />ME 1004-07<br />April 20, 2010<br />
    2. 2. Outline of Presentation<br />Scope of the Project<br />Fuel Cell Background<br />Design<br />Sensors<br />Instrumentation <br />Experimental Methods<br />Evaluation Methods<br />
    3. 3. Scope of the Project<br />A fuel cell membrane test stand was designed and fabricated to evaluate solid polymer electrolytes at the reactant-catalyst-electrolyte interface<br />Three new membranes from the Institute of Macromolecular Chemistry in Kiev, Ukraine were tested and analyzed<br />C-40<br />N-172<br />229<br />Characterizations were made of the membranes and gas diffusion electrodes.<br />The membranes were compared to the Nafion 117 membrane.<br />
    4. 4. What is a Fuel Cell<br />A Fuel Cell works by combining Hydrogen and Oxygen Gas to produce electricity and the only byproduct is water and heat.<br />Fuel cells have also been called Gas Batteries<br />The reaction within a Fuel Cell the opposite of electrolysis.<br />Fuel Cells are classified by the type of electrolyte utilized<br />There were two types of Fuel Cells that were tested<br />Proton Exchange (PEM – acid)<br />Hydroxyl Exchange (Alkaline Fuel Cell)<br />
    5. 5. Types of Fuel Cells<br />PEM Fuel Cell<br />Alkaline Fuel Cell<br />Proton Exchange Membrane<br />Polymer Exchange Membrane<br />Hydroxyl Exchange Membrane<br />Anion Exchange Membrane<br />Anode<br />Anode<br />Cathode<br />Cathode<br />
    6. 6. Fuel Cell Membrane Test Stand<br />A Test Stand was fabricated by modifying an existing fuel cell manufactured by Parker Hannifin TekStakTM Fuel Cell.<br />A fuel cell membrane test stand was designed to evaluate solid polymer electrolytes.<br />The test stand allows for the measurement at the reactant-catalyst-electrolyte interface.<br />Temperature<br />Pressure<br />Humidity<br />Oxygen concentration<br />
    7. 7. Parts of a Fuel Cell<br />
    8. 8. Material Selection<br />Gas Diffusion Electrode<br />Carbon Cloth<br />Porous and Flexible<br />Platinum Catalyst Layer<br />Pt is the most reactive and expensive catalyst<br />Robust design (4 mg/cm2)<br />To isolate membrane performance <br />Gaskets<br />20 mil Silicone Rubber<br />30% compression<br />
    9. 9. Sensors<br />Temperature<br />E type thermocouple<br />Humidity<br />Honeywell relative humidity sensor<br />Compact size <br />Low Cost<br />Pressure<br />Absolute Gas Pressure Sensor <br />3-36 psi range<br />Temperature Compensated<br />Easy Integration<br />5 V supply voltage<br />Oxygen<br />Advanced Micro Instruments Model 60 Oxygen Probe <br />electrochemical sensor type<br />0-25% oxygen range<br />
    10. 10. Integration of Pressure and Oxygen Sensors<br />
    11. 11. Design<br />Flow plate<br />Serpentine Pattern <br />High channel velocity<br />Good water removal<br />High Performance <br />Graphite <br />The flow plate was redesigned to accommodate the sensors <br />Humidity Sensor<br />Needle<br />Oxygen Sensor<br />Pressure Sensor<br />
    12. 12. Design<br />
    13. 13. Instrumentation<br />Data Acquisition System<br />DAQ card<br />NI-6211<br />LabVIEW<br />Graphical programming environment<br />External Power Supply<br />For the oxygen sensor<br />
    14. 14. Instrumentation Setup<br />External Power Supply<br />Electronic Fuel Cell Load Machine<br />Oxygen Sensor<br />DAQ Card<br />Humidity Sensor<br />Pressure Sensor<br />Thermocouples<br />Pressure Sensor Wires<br />
    15. 15. Instrumentation<br />
    16. 16. Instrumentation<br />
    17. 17. Hydrogen and Air Supply Setup<br />
    18. 18. Characterizations<br />Characterizations of the membrane materials and the gas diffusion electrodes were completed. <br />Optical Microscopy<br />Basic morphology of membranes and GDL’s<br />Scanning Electron Microscopy (SEM)<br />Catalyst loading<br />Detailed Morphology of GDL<br />Atomic Force Microscopy (AFM)<br />Topography of Membranes<br />
    19. 19. Optical Microscopy<br />Capability to magnification up to 400 and 1000 times the object’s original size<br />Alkaline Membrane<br />Catalyst Layer <br />
    20. 20. Scanning Electron Microscopy<br />In SEM electrons are used to capture an image instead of light<br />SEM scans the sample with a high energy beam of electrons<br />As electrons hit a sample, other electrons are ejected and converted into other forms<br />typical resolution of SEM is around 5 nm<br />
    21. 21. Scanning Electron Microscope<br />Gas Diffusion Layer 150X<br />Gas Diffusion Layer 1510X<br />
    22. 22. Atomic Force Microscopy<br />AFM consists of a cantilever with a probe mounted at the end<br />The probe is brought near the surface of the specimen and the deflection of the cantilever is measured<br />AFM has a resolution of 0.1 nanometers and can be used to view atoms<br />
    23. 23. Performance Evaluation <br />Polarization Curve<br />Plot of the voltage vs current density<br />Shows “polarization” losses<br />Activation losses<br />Ohmic Losses<br />Concentration Losses<br />Power Curve<br />Plot of power on a voltage vs current graph<br />
    24. 24. Results: Polarization and Power<br />
    25. 25. Results: Temperature<br />
    26. 26. Results: Oxygen Concentration<br />
    27. 27. Results: Experimental Membranes<br />C-40<br />Generate voltage of .856 V with no measurable current<br />Ionic conductivity of 4.1(10-3) S/cm at 15C<br />229 (Alkaline)<br />Generated voltage of .153 V with no measurable current<br />Ionic conductivity of .0112 S/cm when hydrated at 60-80C<br />Nafion 117<br />Generated of .95 V<br />Ionic conductivity of .083 S/cm<br />
    28. 28. Experimental Membranes<br />Voltage of experimental membranes show promising results<br />Still in the initial testing stages<br />Experimental membranes are designed to operate at higher temperatures than Nafion which is limited to below 100C<br />The experimental membranes are thicker than Nafion increasing their resistance<br />Recommend that membranes be made thinner<br />
    29. 29. Challenges and Solutions<br />Electronic Fuel Cell Load<br />Little knowledge of how to use machine <br />Spent hours on phone with manufacturer for weeks<br />Leakage<br />Different gasket shapes<br />Did many leak tests to find out where the fuel cell was leaking<br />Applied vacuum grease to the O-rings<br />
    30. 30. Challenges and Solutions<br />Humidity Sensor<br />GDL’s were not as flexible as originally thought and caused humidity sensor to not fit into it’s designated space<br />Humidity Sensor kept shorting out<br />Added varnish to the flow plate and leads of humidity sensor<br />Added silicone to flow plate and the leads<br />Insulated the leads with jackets<br />Used a Dremmel to shave off any unnecessary plastic from the humidity sensor.<br />Pressure that was safe for the fuel cell stack was much lower than the pressure that the experiments were supposed to take place at<br />
    31. 31. Challenges and Solutions<br />Bolts<br />If the bolts are tightened too much, the gaskets block the channel<br />If the bolts are too loose, then the GDL and membrane don’t have enough contact and there is no current<br />Found optimal torque to be 6 lb-in<br />After one use, Nafion becomes deformed and is pushed into the flow channels by the gaskets and blocks the channel.<br />Thermocouple picking up signals from the EFCL<br />
    32. 32. Design Recommendations <br />Deeper channels<br />Allow for gasket to deform into channel without restricting flow<br />Change flow channel design<br />Eliminate the need for holes in the membranes and gaskets to prevent leakage and cross over of gases<br />Use sensors specifically made to be in a conductive environment <br />Prevent sensors from short circuiting between flow plates or Gas Diffusion Electrodes<br />
    33. 33. Design Recommendations<br />Use a larger fuel cell <br />Add polyurethane coating to thermocouple for “insulation” <br />Know the mechanical properties of the GDL is before designing a modified flow plate<br />
    34. 34. Conclusions<br />A Fuel Cell Test Stand was successfully designed, fabricated, and tested.<br />A data acquisition system was designed and implemented to measure Pressure, Temperature, Oxygen Concentration, and Relative Humidity.<br />Characterizations of Gas Diffusion Electrode and Membrane materials were made.<br />Advanced Laboratory Techniques were learned including Optical Microscopy, Scanning Electron Microscopy, and Atomic Force Microscopy.<br />
    35. 35. Acknowledgements <br />Our Advisors – Dr. Shrestha, Dr. Ghantasala, and Dr. Bliznyuk<br />Dr. V. Schevchenko – Institute of Macromolecular Chemistry<br />Dr. Hathaway<br />Pete Thannhauser<br />Abraham Poot<br />Glenn Hall<br />Rex Harding<br />Melissa Wagner<br />
    36. 36. Any Questions?Thank You<br />

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