For the evaluation and optimization of SOC's a good theoretical understanding of the occurring transport mechanisms is necessary. Since a large number of gradients occur at the same time in electrochemical systems, the thermodynamics of irreversible processes is particularly suitable for describing the coupled transport mechanisms. For the heat flux and the oxygen ion flux in the electrolyte, for example, a dependence on the temperature gradient and on the gradient of the electrochemical potential follows in each case. From the respective fluxes (here heat flux and oxygen ion flux) and driving forces (here temperature gradient and gradient in the electrochemical potential of the oxygen ions), a direct determination of the entropy production rate is possible, which in turn has a decisive effect on the temperature field and thus provides important information for the design and determination of the operating strategy of the cell.
Based on the detailed modeling of individual transport mechanisms, simulation models for the description of single cells and stacks (series connection of several single cells) are created at the institute. The models aim at the highest possible accuracy in describing the steady-state and transient operating behavior of the SOC in order to enable a design and holistic optimization for the respective application. In order to validate the specially developed simulation models, experimental investigations are also carried out on a laboratory scale.
