Modeling support for solid oxide fuel cell-component development

Solid oxide fuel cells (SOFCs) have high potentials for future energy demands by converting the chemical energy of suitable fuels like hydrogen and carbon monoxide directly to electric energy and heat. To obtain an appropriate power supply, several SOFC cells are connected in series to form a SOFC stack and furthermore, multiple SOFC stacks can be combined to achieve higher power scalability up to numerous kilowatts. One major advantage of SOFC technology is the ability to use higher hydrocarbon fuels; however, additional fuel processing (i.e. partial catalytic reformer and tail gas oxidizer) is necessary. Consequently, different components interact to form a SOFC system. The modeling group at Fraunhofer IKTS is dealing with different aspects of SOFC stack and component simulation. In thi s work, an overview of our modeling strategies, partially based on homogenisation methods, for both SOFC stacks and components are given. In order to operate one or multiple SOFC stack(s) efficiently, ideal operating conditions (e.g. uniform gas supply, low thermal gradients) are of great importance. A detailed Hotbox model is presented, comprising 8 SOFC stacks, cathode flow in- and outlets. This model helps to compare different flow geometries and their influence on fuel cell performance. Additionally, heat removal can be studied. With the help of component models, the field distributions of temperature and species concentrations in the catalytic reforming- and catalytic burner device can be analysed. The temperature distribution is also important for understanding the ageing process of the devices because high temperatures in the catalyst result in a faster performance decay of the device. The knowledge about the temperature and species distributions should enable use to optimize these components.