Dynamic Solid Oxide Fuel Cell Modelling for Non-steady State Simulation of System Applications

Abstract: Most of the world's energy generation is based on fossil fuels such as coal and oil, which already today but even more in the future, will cause various problems. One issue is their limited availability, which stands in conflict to the increasing global energy consumption. Another problem is the carbon dioxide generation caused by burning fossil fuels for energy production, and is thought to be one of the main contributors to global warming. In order to counteract this development, alternative ways for energy production have to be found, which are independent of fossil fuels, have low greenhouse gas emissions, and high efficiency. One of these alternatives, fulfilling all the mentioned requirements, is the fuel cell technology. Although, the commercial breakthrough has not been realized yet, intensive research activity is driving the technology towards this goal. Besides experimental test rigs and system pilot plants, research within this area requires computational models to simulate the component performances. Of special importance is the dynamic modelling of the SOFC component, in order to provide knowledge about its transient behaviour, which is important for development of control strategies. This thesis focuses on the development and application of dynamic SOFC models, which are used to simulate the SOFC performance. Furthermore, the presented SOFC models are able to predict the effects of operation parameter changes, such as load, pressure, mass flow or temperature changes. A validation and benchmarking of one of the developed tools has been carried out, resulting in good agreement with experimental and simulation data. By using the developed models, analysis of the dynamic behaviour of the SOFC has been carried out, including SOFC start-up and shut-down processes. To investigate the dynamic behaviour of the SOFC in system context, a model of an atmospheric SOFC system for stationery energy production has been developed. This tool can be used to illuminate the transient system characteristics, which are the basis for test system design.