Modelling of the SOFC Generator in the Hybrid Power Plant Project

Kurzfassung

Hybrid power plants offer the advantage of highly efficient power generation. The DLR Institute of Technical Thermodynamics is part of a research partnership developing a hybrid power plant. The project is divided into 3 phases lasting until 2012. The first phase focuses on modelling the components of the power plant. A model library for MATLAB Simulink containing several fuel cell models as well as balance of plant components has been developed. Utilizing these models the control system of the hybrid power plant can be designed and tested before the plant is built. To enable the control model to fit the needs of a real hybrid power plant high descriptive quality of the component models is required. Therefore the SOFC generator models are validated in house. DLR-TT has many years of experience in testing single cells as well as short stacks in SOFC as well as in PEMFC. For this project, a Siemens SFC-5 system has been installed in Stuttgart. This system enables DLR to verify tubular SOFC models. In addition a new test rig is going to be built allowing measuring pressurized planar SOFC. Test results from both experimental set ups will be used to validate the models. The presentation focuses on the modelling performed so far in the project. A locally resolved fuel cell model will be presented. The model features air inlet tube and the fuel cell, both interacting with each other resulting in a 1+1D model. Radiation heat transfer as well as convective heat transfer and heat conduction is included in the models. The fuel cell model is based on a Nernst approach. Open circuit voltage as well as over potentials are calculated depending on the local gas composition and temperatures.