Diffusion bei Wasserstofftanks - effektive Diffusionskoeffizienten

Kurzfassung

The increasing importance of hydrogen as an alternative energy carrier is often described as the foundation of the energy transition. Especially in the mobile sector, the energy transition is inevitable. Therefore, mobile storage and its characteristics are an important field of research. This thesis pays special attention to the storage of hydrogen as a compressed gas. The diffusion properties of the storage technology currently used in the transport sector, the type IV hydrogen pressure vessel, are examined in more detail. The aim of this work is to determine the effective diffusion or conductivity coefficients of hydrogen pressure vessels, made of fibre-reinforced plastics. Various methods have been used to answer this research question. These have analytical and numerical approaches. The different methods were compared in terms of time, accuracy and quality of results. When comparing these methods, it was found that the analytical methods, especially the variational principle according to Hashin and Shtrikman, can be considered as the primary method in terms of determining optima of the fibre volume fraction. This is because this variational principle imposes bounds, depending on the fibre volume fraction, around the real effective conductivity coefficient. If anisotropically distributed or damaged microstructures are considered, the numerical RVE method is preferable to the analytical one, since the analytical methods, which are competitive with the numerical method in terms of result quality and accuracy, prescribe an isotropically distributed microstructure. An implementation of the analytical method in a numerical simulation using the RVE method is conceivable and could be implemented through further research work.