Fuel Cell Modelling. The principle of the fuel cell is simple and can be assimilated as a reverse electrolyse. More precisely, it is a controlled electrochemical transformation of hydrogen and oxygen, with a production of electricity, water and heat. The reaction of hydrogen with oxygen is given by; Rather than using combustion to react hydrogen with oxygen, a fuel cell uses an electro-chemical process. Hydrogen is fed into the fuel cell at the anode where the atoms are stripped of electrons. The electrons flow around the electrolyte in a circuit from the anode to the cathode where it is combined with oxygen and the hydrogen ions to form water. H2 2H+ + 2e- 4H+ + O2 + 2e- 2H2O Depending on the type of fuel cell, the reaction, which is exothermic, can take place at different temperatures, from tens of degrees Celsius to a thousand degrees Celsius. The principle function of the fuel cell is common to all types, but the operating temperatures and the electrolyte type makes the fuel cells specifications different (adapted to certain applications). Figure 16 shows the basic fuel cell model created in GES. Figure 16: Fuel cell component model block Table 13 shows some common types of fuel cell technologies. Type of Fuel Cell Common Electrolyte Operating Temperature Typical Stack Size Efficiency PEM Polymer Electrolyte Membrane Perfluoro Sulphonic Acid 50-100oC < 1kW-100 kW 60% Transportation 35% Stationary AFC Alkaline Solution of Potassium Hydroxide soaked Matrix 90-100oC 10-100 kW 60% PAFC Phosphoric Acid Phosphoric Acid soaked matrix 150-200oC 400 kW 40% MCFC Moltan Carbonate Molten Lithium, Sodium or Potassium Carbonates soaked matrix 600-700oC 300 kW – 3MW 45-50% SOFC Solid Oxide Yttria stabilised Zirconia 700-1000oC 1 kW – 2 MW 60% Table 13: Common types of fuel cell technology As the table above shows, fuels cells vary dramatically depending on their electrolyte and working temperatures. The selection of an appropriate fuel cell will depend on the specific application and the required power output. Details of specific fuel cells are discussed in D3.1. The required inputs and outputs for the basic fuel cell model in GES are shown in Table 14. Type Name Gates Paramet ers FC_CELL_UNIT9 3 Version INOMAN.1 Help Fuel cell unit Created Fuel type 1 TNO SWBS 2241 4-11-2013 gate # Index Power [In,Out] effort cal unit flow cal unit parameter # name value unit 1 0 Out u func [V] i [A]
