Life time assessment of cryo-compressed hydrogen (CcH2) storage tanks

Abstract

Cryo-compressed hydrogen storage (CcH2) tanks made of fibre reinforced plastics are one response to the issue of alternative fuel concepts and the increasing demand for lightweight structures in automotive industry. The storage of hydrogen as cryo-compressed gas results in a very high energy density and can satisfy long range requirements. The operation temperature regime of the tank ranges from 85°C down to -240°C and covers pressures up to 350 bar. Due to a repeated refueling and discharge, the proof of fatigue strength under combined pressure and low temperature cycles is an important challenge. In the research Project HyMod, funded by the German Federal Ministry for Economic Affairs and Energy, the DLR together with the other partners, develops an FEM based integrated simulation tool for the lifetime prediction of CcH2 tanks. The presented virtual tool chain combines the CFD simulations, mapping methods and material models developed for the lifetime assessment of components of cryogen hydrogen storage systems within the HyMod project. The tool chain is used successfully to predict the lifetime of CcH2 vessels exposed to different thermo-mechanical load scenarios. Furthermore the influence of different pre-service states, such as the autofrettage, on the durability of the structure is analyzed. The numerical predictions are in a good agreement with the results of cyclic tests on pressure vessels which have also been performed within the research project. In further developments of hydrogen storage tanks, the presented tool permits reliable decisions for changes in concept and design.