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Schlagwörter:
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Zusammenfassung:
3D simulation of a symmetric MCFC stack model
M. Pfafferodt1, P. Heidebrecht2, K. Sundmacher1,2,*
1Otto-von-Guericke University Magdeburg, Chair of Process System Engineering, Universitätsplatz 2, 39106 Magdeburg, GERMANY
2Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, 39106 Magdeburg, GERMANY
*Corresponding Author: tel. +49 391 6110351; fax: +49 391 6110523.
Introduction
The Molten Carbonate Fuel Cell (MCFC) allow the efficient conversion of chemically bound primary energy into electrical energy. The life time and efficiency of an MCFC is strongly connected to the temperature profile within the fuel cell stack. The temperature is determined by the interaction of the endothermic methane reforming process and the heat releasing electrochemical reactions [1]. The electrochemical reactions take place at the fuel cells' electrodes whereas the reforming reaction takes place in special units within the fuel cell stack - the Indirect Internal Reformer (IIR) units. Thus not only the heat sources and heat transport inside each cell is relevant but also the heat conduction in stack direction.
Modelling
A tool for a better understanding of the temperature profile are simulations of the fuel cell stack. Because of the symmetric structure of the stack, only four fuel cells and one IIR unit are simulated. The description of the fuel cells is based on previously works where a model of one fuel cell was validated [3].
Results
The simulation results show a parabolic temperature profile from the IIR unit to the fuel cells. The temperature differences in stack direction are in the same order of magnitude as the temperature differences within the solid phase of one fuel cell or the IIR unit. Wherefore this temperature distribution has to be taken into account for an analyses of the MCFC system.
Discussion
Using the symmetric stack model the molar flow, the temperature and the composition of the gas phase within the IIR unit and the anode and cathode compartments as well as the temperature of the solid and the current density of each cell can be predicted. Further more the results are used to propose possible improvements of the model and draw conclusions for an optimal design of the fuel cell stack and its components.
[1] P. Heidebrecht; Modelling, Analysis and Optimisation of a Moltan Carbonate Fuel Cell with Direct Internal Reforming (DIR-MCFC); Fortschritt-Berichte VDI-Verlag; Düsseldorf, 2005
[2] M. Gundermann, et. al.; Validation of a mathematical model using an industrial MCFC plant; J. of Fuel Cell Science and Technology; 3 (3) 303-307; 2006
