Recent Developments in 3D Multiphysics Modelling of Whole Fuel Cell Systems for Assisting Commercialisation and Improved Reliability

Abstract

3D multiphysics modelling of fuel cell components and fuel cell systems has been a core research field since many years. The simulation assisted research and development improves the understanding and overall success of the fuel cell technology, in particular the high temperature SOFC technology. The ultimate goal has been to support the commercialisation of the technology. This can be enhanced by improving the understanding and knowledge of the utilised fuel cell systems. Especially, gaining detailed information about their durability and life duration is of paramount importance. As a fuel cell system consists of many components like the fuel cell stack, reformer, afterburner, heat exchanger etc., it is important to account for the coupled processes, occurring within each component and their interaction with the neighbour components. This needs to be mastered, in order to improve the overall technology. However, this requires a large amount of experimental facilities, which have also limits. Even the presence of long-term testing results of individual solid oxide fuel cells are not sufficient yet to declare their autonomous performance as the same within the system. Moreover, many years are required that is constraining the scientists; thus, the assistance of 3D multiphysics modelling is attractive. If we consider that the technology has heating-up, operation and shut-down stages, broad knowledge is required for a safe and reliable SOFC development. For this purpose, the developed full scale multiphysics model reflecting a 5kW full integrated SOFC module is employed for the solution of the complex 3D problem and to gather invaluable information about various questions. The used numerical model of the complex 3D system depicts the true physical resolution of the components, as to account for the complex geometrical effects. Material non-linearity, including the temperature dependence of material properties, as well as the material models that describe the elastic, plastic and creep deformation of the materials are implemented within the model. Each component process and parameters are determined from component and system test facilities. To shed light to the long-term system behaviour, recent attention has been given to the steady operation and the durability response of the interacting components. The detailed 3D stress-strain field of the whole system could be analysed and invaluable practical information about the critical locations within the interacting whole system could be determined. To interpret the long-term reliability of the system, the thermomechanical fatigue behaviour of the critical system regions have been investigated in detail to predict and understand the durability under cyclic load. The results give a flair of the life expectation of a system subjected to current circumstances.