Fraunhofer Institute for Production Technology IPTResearch Project "smartVessel"
Hydrogen pressure vessels must be safe, durable and capable of withstanding prolonged high pressure
The ability to store hydrogen under high pressure at around 700 bar will become essential for stationary and mobile energy supply in the electromobility market. Pressure vessels made of fiber-reinforced plastics (FRP) have just the right material properties to store hydrogen efficiently and safely. Despite this, these materials have not yet been able to establish themselves on the market due to a lack of sufficient data on their behavior in specific applications compared with that of conventional metal vessels. Periodic, non-destructive tests (NDT) such as ultrasound and visual inspection have already contributed to an increase in the reliability and safety of these components in the past. However, one major limitation of these test methods is they cannot ensure with a high enough degree of certainty that no damage will occur during manufacture, between inspections or in the operation of the pressure tanks. In the worst-case scenario, damage to the vessel structure could result in hydrogen leakage and have expensive consequences for the operator as well as posing a health risk. To eliminate this risk, pressure tanks are currently designed and manufactured with a high safety margin. The consequences of this are significant excess material quantity, manufacturing time, energy consumption and cost.
Continuous monitoring of the condition and remaining service life of the pressure vessel
Improved predictive accuracy with regard to the safety of hydrogen pressure vessels both during refueling and operation, thereby enabling the remaining service life of the vessels to be forecast is the aim of intelligent condition monitoring. Based on Structural Health Monitoring (SHM) of the tanks, maintenance operations can be scheduled depending on the condition of the vessel instead of periodically. Operating risk can then be assessed continuously on the basis of the monitoring data. This eliminates the limitations of conventional NDT methods, increasing user confidence in the technology of FRP hydrogen pressure vessels. Ultimately, this paves the way for a reduction in the safety factor required in the design of pressure vessels.
Lower maintenance costs and more safety as a result of integrated sensors
The aim of the “smartVessel” research project is to reduce maintenance cost for hydrogen tanks by exploiting the entire service live of a pressure vessel without safety risks. In addition, it is anticipated that insights will be gained into the extent to which the safety factor can be reduced without lowering the safety level. This will be achieved by integrating glass fiber-based sensors into the fiber-reinforced plastic laminate to monitor the condition of the hydrogen tank during the ongoing manufacturing process. A sensor within the fiber optic can be approximately 1 meter in length and permits continuous measurement at thousands of points distributed along this distance. The current load condition and the remaining service life can be determined by evaluating the sensor data within the fibers. In the course of this project, the Fraunhofer IPT will explore ways of integrating the sensors into the layer structure of the thermoplastic composite tank reinforcement via an automated, laser-assisted tape winding process and will develop both the sensors and the associated measurement technology.
Consortium
Project Coordinator:
- Institut für Textiltechnik of RWTH Aachen University (Aachen, Germany)
Active Project Partners:
- Air Liquide S.A. (Paris, France)
- F.A. Kümpers GmbH & Co. KG (Rheine, Germany)
- fibrisTerre Systems GmbH (Berlin, Germany)
- Fraunhofer IPT (Aachen, Germany)
- Heracle GmbH (Jena, Germany)
- SimpaTec GmbH (Aachen, Germany)
- Wölfel Engineering GmbH & Co. KG (Höchberg, Germany)
Associated Project Partners:
- Energy Agency NRW (Düsseldorf, Germany)
- Evonik Resource Efficiency GmbH (Marl, Germany)
- Volkswagen Aktiengesellschaft (Wolfsburg, Germany)