MATHEMATICAL MODELING OF A MOLTEN-CARBONATE FUEL CELL USING MATHCAD David Blekhman Associate Professor California State University, Los Angeles, CA, USA Stephen T. McClain Assistant Professor Baylor University Waco, TX, USA

Molten-Carbonate Fuel Cell Operation MCFC Operation Very slow Reactions provide specific mole count David Blekhman, PhD 6th International Fuel Cell Science, Engineering and Technology Conference

Code Execution Block Diagram Project David Blekhman, PhD 6th International Fuel Cell Science, Engineering and Technology Conference

Project Description Determine open cell voltage potential as reactants flow in a high-temperature fuel cell. Project In a molten-carbonate fuel cell David Blekhman, PhD 6th International Fuel Cell Science, Engineering and Technology Conference

Fuel Reforming/Equilibrium at inlet and through the fuel cell anode Water-gas shift reaction Steam-reforming reaction Equilibrium constants, can be given or calculated Fuel Reforming Fuel is heated to the FC operational temperature. As the fuel cell reaction proceeds, the gas compositions on both the anode and cathode sides continuously change. For each mole of hydrogen reacted, one mole of water and one mole of carbon dioxide are generated on the anode. On the cathode, a half mole of oxygen and one mole of carbon dioxide disappear. This means that at each new step of the gas composition calculation, after all the corresponding moles of reactants on the anode are added and subtracted, the elements conservation coefficients Eqs. 14 and 15 are determined. Three element conservation equations for H, O and C David Blekhman, PhD 6th International Fuel Cell Science, Engineering and Technology Conference

Fuel Reforming/Equilibrium at inlet and through the fuel cell anode Fuel Reforming Fuel is heated to the FC operational temperature. As the fuel cell reaction proceeds, the gas compositions on both the anode and cathode sides continuously change. For each mole of hydrogen reacted, one mole of water and one mole of carbon dioxide are generated on the anode. On the cathode, a half mole of oxygen and one mole of carbon dioxide disappear. This means that at each new step of the gas composition calculation, after all the corresponding moles of reactants on the anode are added and subtracted, the elements conservation coefficients Eqs. 14 and 15 are determined. David Blekhman, PhD 6th International Fuel Cell Science, Engineering and Technology Conference

Fuel Reforming/Equilibrium at inlet and through the fuel cell anode Fuel Reforming Fuel is heated to the FC operational temperature. As the fuel cell reaction proceeds, the gas compositions on both the anode and cathode sides continuously change. For each mole of hydrogen reacted, one mole of water and one mole of carbon dioxide are generated on the anode. On the cathode, a half mole of oxygen and one mole of carbon dioxide disappear. This means that at each new step of the gas composition calculation, after all the corresponding moles of reactants on the anode are added and subtracted, the elements conservation coefficients Eqs. 14 and 15 are determined. Conjugate Gradient David Blekhman, PhD 6th International Fuel Cell Science, Engineering and Technology Conference

Fuel Choices Fuel /Gas H2 H2O CO CO2 CH4 N2 Low-Btu 1, dry 71°C 0.213 0.193 0.104 0.011 0.479 Low-Btu 2, dry 60°C 0.402 0.399 0.199 Low-Btu 2, wet 60°C 0.336 0.164 0.333 0.166 Low-Btu 2, 650°C 0.2319 0.2673 0.0988 0.2344 0.0017 0.1668 Fuels and Oxidizers David Blekhman, PhD 6th International Fuel Cell Science, Engineering and Technology Conference

Oxidizer Choices 1. 30% O2-60% CO2-10%N2 2. 30% O2-70% CO2 3. 13% O2-26% CO2-61%N2 --from air Fuels and Oxidizers Stoichiometry =0.5 (twice oxidizer) Carbon dioxide =twice that of Oxygen David Blekhman, PhD 6th International Fuel Cell Science, Engineering and Technology Conference

Fuel Flow Results Utilization David Blekhman, PhD 6th International Fuel Cell Science, Engineering and Technology Conference

Fuel / Oxidizer Utilization Fuel mixture composition as it flows through the fuel cell David Blekhman, PhD 6th International Fuel Cell Science, Engineering and Technology Conference

Nernst Potential Nernst Potential Open circuit potential as a function of fuel utilization in the fuel cell David Blekhman, PhD 6th International Fuel Cell Science, Engineering and Technology Conference

Topics Reviewed by the Project Psychrometrics Ideal Gas Mixtures Reacting Systems Chemical Equilibrium Fuel Cells Conclusions David Blekhman, PhD 6th International Fuel Cell Science, Engineering and Technology Conference