171 sreenivasulu

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171 sreenivasulu

  1. 1. AN EXPERIMENTAL STUDY ON FLOW FIELDS IN A PEM FUEL CELL B. Sreenivasulu Dept of Chemical Engg, G V P College of Engineering, Visakhapatnam-48. V. Dharma Rao , B.Govinda Rao Dept of Mechanical Engg, G V P College of Engineering, Visakhapatnam-48. S.V. Naidu, Dept of Chemical Engineering, Andhra University, Visakhapatnam-3. Vasu Gollangi Fuel Cell and Renewable Energy, BHEL R&D, Hyderabad.
  2. 2. • A fuel cell is an electrochemical energy converter that converts chemical energy of fuel directly into DC electricity. • Fuel cells resemble batteries in many ways, but in contrast to them they do not store the chemical energy, fuel has to be continuously provided to the cell to maintain the power output. Typically, a process of electricity generation 1.Combustion of fuel converts chemical energy of fuel into heat, 2.This heat is then used to boil water and generate steam, 3. Steam is used to run a turbine in a process that converts thermal energy into mechanical energy, and finally 4. Mechanical energy is used to run a generator that generates electricity.
  3. 3. Typical Characteristics of Fuel Cells Primary Application Electrilyte Operating Temperature Range Charge Carrier Prime Cell Component Catalyst Primary Fuel Start-up-Time Power Density (KW/m3) Fuel Cell Efficiency AFC Space Vehicles and drinking water Concentrated (30 – 50%) KOH in H20 PAFC Statinory Power MCFC Statinory Power SOFC Vehicle auxiliary Power YttriumStabilized Zirkondioxide PEMFC Automotive and Statinory Power Polymer (plastic) Membrane DMFC Portable Power Concentrated 100% Phosphoric acid 50 -200 OC 150 – 200 OC Molten carbonate retained in a ceramic matrix of LiALO2 600 - 700 OC 700 – 1000 OC 50 – 100 OC OHCarbon-based H+ CO3OGraphite-based Stainlees Steel Ceramic H+ H+ Carbon-based Carbon-based Platinum H2 min 1 Platinum H2 Hours 0.8-1.9 Nickel H2, CO, CH4 Hours 1.5 - 2.6 Perovskitse H2, CO Hours 0.1 -1.5 Platinum H2 Sec-min 3.8 - 6.5 Pt-Pt/ru Methanol Sec-min 0.6 50 - 60% 55% 55 - 65% 55 - 65% 50 - 60% 30 - 40% Polymer (plastic) Membrane 30 – 60 OC
  4. 4. Advantages of PEM fuel cells: • Low operating temperature (<100oC) • Quiet operation • High power density • Quick startup and • Zero emissions, which leads directly to a reduction of air pollution and greenhouse gases.
  5. 5. Working of Fuel Cell Components
  6. 6. Components of Fuel Cell
  7. 7. Functions of components Component Description Common Types Proton exchange membrane Enables hydrogen protons to travel from the anode to the cathode. Persulfonic acid membrane (Nafion 112, 115, 117) Catalyst layer Breaks the fuel into protons and Platinum/carbon catalyst electrons. The protons combine with the oxidant to form water at the fuel cell cathode. The electrons travel to the load. Gas diffusion layer Allows fuel/oxidant to travel through the porous layer, while collecting electrons Carbon cloth or Toray paper Flow field plate Distributes the fuel and oxidant to the gas diffusion layer Graphite, stainless steel Gasket Prevent fuel leakage, and helps to distribute pressure evenly Silicon, Teflon End plate Holds stack layers in place Stainless steel, graphite, polyethylene, PVC
  8. 8. Experimental Setup The experimental set up contains a single PEM fuel cell with active surface area 9.6 9.8 cm. The membrane electrode assembly (MEA) consists of  Nafion 1135 (88 µm)  Gas diffusion layers (400 µm)  Catalyst layers • Catalyst used is carbon supported platinum • Catalyst ink is applied as a layer on the GDL • The catalyst loading on the anode-side is 0.15 mg/cm2 with a thickness of catalyst layer of 20 µm • A catalyst loading of 0.3mg/cm2 is used on the cathodeside with a thickness of catalyst layer of 40 µm The MEA is placed between two graphite plates and is pressed between gold-coated copper plates.
  9. 9. Different Parameters studied  Effect of Channel geometry • 4-Serpentine • Interdigitated • Dual-inlet-single-outlet  Effect of Stoichiometry
  10. 10. 4-Serpentine flow channel fig
  11. 11. Schematic diagram of 4-serpentine flow channel
  12. 12. Dimensions of the computational domain Channel length Channel width :98mm :1.5mm Rib width :2mm Channel height :0.8mm GDL thickness :0.4mm Anode Catalyst-layer thickness :0.02mm Cathode Catalyst-layer thickness :0.04mm Membrane thickness :0.088mm Active area :94cm2  All the components are meshed and assembled in GAMBIT.
  13. 13. Interdigitated flow channel
  14. 14. Photograph of single PEM fuel cell Experimental set up
  15. 15. Effect of Stoichiometry Pressure =1atm, H2 flow rate=0.32lpm,Cell temperature=40oC, Anode and Cathode humidification temperature=30oC 1.0 Dual inlet single outlet flow channel 0.9 % excess oxygen flow rate 150 100 50 Voltage (V) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0 10 20 Current (A) 30 40
  16. 16. 1.0 Interdigitated flow channel 0.9 % excess oxygen flow rate 150 100 50 Voltage (V) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0 10 20 Current (A) 30 40
  17. 17. Effect of flow Channel Pressure =1atm, H2 flow rate=0.32lpm,O2 flow =0.22lpm,Cell temperature=40oC, Anode and Cathode humid temp=30oC 1.0 50% excess O2 flow rate 0.9 4-Serpentine flow channel Interdigitated flow channel Dual inlet single outlet flow channel Voltage(V) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0 10 20 Current(A) 30 40
  18. 18. Pressure =1atm, H2 flow rate=0.32lpm,O2 flow =0.28lpm,Cell temperature=40oC, Anode and Cathode humid temp=30oC 1.0 100% excess flow rate 0.9 Type of channel 4-Serpentine Interdigitated Dual inlet single outlet Voltage(V) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0 10 20 Current(A) 30 40
  19. 19. Pressure =1atm, H2 flow rate=0.32lpm,O2 flow =0.36lpm,Cell temperature=40oC, Anode and Cathode humid temp=30oC 1.0 150% excess flow rate Type of flow channel 0.9 4-Serpentine Interdigitated Dual inlet single outlet Voltage(V) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0 10 20 Current(A) 30 40
  20. 20. Effect of Back pressure 18 without backpressure Type of channel 4-Serpentine Interdigitated Dual inlet single outlet 16 14 Power(W) 12 10 8 6 4 2 0 0 10 20 Current(A) 30 40
  21. 21. Effect of Back pressure 20 12 in H20 backpressure Type of channel 18 4-Serpentine Dual inlet single outlet Interdigitated 16 Power(W) 14 12 10 8 6 4 2 0 0 10 20 Current(A) 30 40
  22. 22. Hysteresis study fig Pressure =1atm, O2 flow rate =0.36lpm, H2 flow rate=0.32lpm Cell and anode humid temp=40oC ,Cathode humid temp=35oC 1.0 Dual inlet single outlet flow channel 0.9 Voltage(V) 0.8 forward backward 0.7 0.6 0.5 0.4 0.3 0.2 0 5 10 15 Current(A) 20 25 30
  23. 23. Conclusions  As the oxygen flow rate is increased, there is an increase in the cell voltage due to maintaining sufficient oxygen on the cathode catalyst surface and carryover of water by oxygen.  When the flow rate is doubled (0.2 to 0.4 lpm) a 10% increase is found in power output (17.7 to 19.4W).  Under identical operating conditions, at 25A current the fuel cell gives the highest voltage with 4-serpentine flow field plates (0.6V). The interdigitated and dual-inlet-single-outlet flow geometries occupy the second and third positions (0.48 and 0.4V) respectively in the performance.  The 4-serpentine and dual inlet and single outlet flow channels show improvement in overall performance and power with an increase in back pressure.
  24. 24.  References: 1. Hawang,J.J. , Hawang,H.S. (2002).Parametric studies of a double-cell stack of PEMFC using GrafoilTM flow-field plates. Journal of Power Sources, 104:24-32. 2. Wang.L., Husar,A. , Zhou.T, Liu,H. (2003). A Parametric study of PEM fuel cells performances. International Journal of Hydrogen Energy, 28: 1263-1272. 3. Wang,L., Liu,H. (2004). Performance studies of PEM fuel cells with interdigitated flow field. Journal of Power Sources, 134: 185–196. 4. Hermann,A., Chaudhuri,T., Spagnol,P. (2005), Bipolar plates for PEM fuel cells: A review. International Journal of Hydrogen Energy, 30,12: 1297-1302. 5. Yan,W.M., Yang,C.H., Soong,C.H., Chen,F., Mei,S.C. (2006). Experimental studies on optimal operating conditions for different flow field designs of PEM fuel cells. Journal of Power Sources, 160: 284-292. 6. Maher A.R. Sadiq Al-Baghdad and Haroun A.K Shahad Al-Janabi, (2007). Influence of the design parameters in a proton exchange membrane (PEM) fuel cell on mechanical behavior of the polymer membrane. Energy & Fuels, 21: 2258-2267. 7. Wang, X.D., Duan,Y.Y., Yan,W.M., Peng,X.F. (2008). Local transport phenomena and cell performance of PEM fuel cells with various serpentine flow field designs. Journal of Power Sources, 175:397-407.
  25. 25. 8. Kuo, J.K., Yen, T.S., Chen, C.K. (2008). Improvement of performance of gas flow channel in PEM fuel cells. Energy Conversion and Management, 49, 10: 2776-2787. 9. Jeon, D.H., Greenway,S, Shimpalee,S., Van Zee, J.W. (2008). The effect of serpentine flow-field designs on PEM fuel cell performance. International Journal of Hydrogen Energy, 33, 3:1052-1066. 10. Kloess, J.P., (2009). Investigation of bio-inspired flow channel designs for bipolar plates in proton exchange membrane fuel cells, Journal of Power Sources, 188,pp. 132-140. 11. Hamilton,P.J. and Pollet,B.G. (2010). Polymer Electrolyte Membrane Fuel Cell (PEMFC) Flow Field Plate: Design, Materials and Characterisation. Fuel Cells, 10,4: 489-509.
  26. 26. THANK YOU 27

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