Liner Collapse of polymer liner composite hydrogen storage tank : initiation and effect of pressure cycles – colline

In the framework of this project, the effect of pressure cycles on a liner collapse will be studied thanks to thermo-mechanical fatigue tests on representative specimens. The analysis of such aged specimens will lead to the definition of an end of life and/or a loss of performance resulting from cycling criteria. In parallel, tests in hydrogen will be carried out on representative samples of a liner-composite assembly to identify the mechanism at the origin of the liner collapse. These approaches on specimens will be validated by comparison with tests on composite tanks. This will allow the development of predictive models of liner collapse occurrence and fatigue lifetime of a tank with a liner collapse.

the project will lead to recommendations for the industry on the design of cylinders and their operating conditions to optimize lifetime, as well as on qualification tests of future cylinders and possible critical collapse size for withdrawal of cylinders in service.

The consortium expects recommendations for safe operation of hydrogen storage composite pressure vessels that will allow fasterimplementation in the field.

- new multiphysics models
- progress on fatigue behavior of polymers
results will be proposed in symopsia and journals.

The development of hydrogen as a reliable energy vector is strongly connected to the performance and level of safety of the components of the supply chain. In this respect, achieving an efficient storage is crucial to address transition markets and automotive markets. For near term, compressed hydrogen storage is currently the most promising technology. To achieve required performance in terms of autonomy and weight efficiency, hydrogen must be stored at pressure up to 700 bar in carbon fibers composites cylinders with a polymer inner shell called liner. Recent observations show that the polymer liner can collapse and deform permanently during cylinder gas emptying. The extend of the liner collapse depends on the pressure in the cylinder, the remaining pressure after emptying, emptying flow rate and the nature of the gas. During hydrogen cycling, the liner is subjected to mechanical and thermal (due to gas heating during filling) loads. The effect of such gas cycling on a liner presenting collapse is currently unknown. A liner collapse could crack or the barrier properties could be affected after some gas cycles. The induced tightness loss could have dramatic consequences. The lack of knowledge on the impact of gas cycles on the lifetime of a composite tank appears as an issue to the development of the hydrogen energy from economic, safety and regulatory standpoints. It is thus necessary to address it in a research project to gain knowledge on the impact of gas cycles on the lifetime of a tank presenting a liner collapse and on the identification of the initiation mechanism and its occurrence conditions in term of pressure and emptying flow rate. These are the main objectives of the project COLLINE, submitted to the French call “AAP ANR MATETPRO 2013. The project gathers an industrial partner, Air Liquide, end-user of composites cylinders with experience on the cylinder supply chain and on tests in gas and Institut Pprime/ISAE-ENSMA, acknowledged for its competencies in experimental, theoretical and numerical mechanics to address multi-physics items (thermo-mechanical and diffuse-mechanical loads in particular) and composites structure durability.
In the framework of this project, the effect of pressure cycles on a liner collapse will be studied thanks to thermo-mechanical fatigue tests on representative specimens. The analysis of such aged specimens will lead to the definition of an end of life and/or a loss of performance resulting from cycling criteria. In parallel, tests in hydrogen will be carried out on representative samples of a liner-composite assembly to identify the mechanism at the origin of the liner collapse. These approaches on specimens will be validated by comparison with tests on composite tanks. This will allow the development of predictive models of liner collapse occurrence and fatigue lifetime of a tank with a liner collapse. Finally, the project will lead to recommendations for the industry on the design of cylinders and their operating conditions to optimize lifetime, as well as on qualification tests of future cylinders and possible critical collapse size for withdrawal of cylinders in service.