| Fuel cell which can directly convert the chemical energy of the fuel into electricity is one of the most promising technologies for power generation. Widely regarded as a potential alternative in the electric utility, the fuel cell has low environmental impact due to the high efficiency and electrochemical oxidation of the fuel. Of the various types of fuel cells, solid oxide fuel cell (SOFC) with its high temperature exhaust gases at elevated pressure makes it suitable for integration with a heat engine, such as a gas turbine (GT). The power system based on such a cycle is expected to achieve a higher efficiency and increased power output due to better thermal utilization.; A one-dimensional dynamic model of a tubular SOFC, based on the electrical quantities, chemical reaction equilibrium and energy balance, is proposed in this study. It can predict the SOFC characteristics at the steady states and also at transient operating states. Furthermore, the temperature, current density and gas concentration distribution along the axial length of the cell ca be analyzed individually. The accuracy and reliability of this model is demonstrated by comparisons with experimental data from the literature. In addition to the SOFC model a dynamic compressor and a gas turbine models are also developed. In the proposed model the dynamic performance including the losses is determined from the compressor and turbine geometry and not from the experimentally determined characteristic performance curves. Various types of losses are mathematically modeled for developing compressor and gas turbine characteristics. Comparison with experimental data is performed to validate these models.; The component models developed are used to study a pressurized tubular SOFC/GT hybrid system. The system is built and simulated to investigate the system performance and dynamic behavior. The major components of the system studied include a SOFC, two air compressors, two gas turbines, a combustor, an external reformer, a heat recovery steam generator (HRSG), three heat exchangers and an intercooler.; All the modeling and simulations are carried out in the VTB, a software for prototyping of large-scale, multi-technical dynamic systems. It allows proof-testing of new designs prior to hardware construction. Due to the nature of the VTB simulation environment and its intended user audience, it enables experts to build models within their domain of expertise and execute those models in a system. |
