HRS Model II

Hydrogen filling stations, i.e. stations for filling cars, buses, lorries or filling stations for trailers, containers or ships, have one thing in common: their thermodynamic processes have a significant influence on the distribution of contaminants in the system. Water as a contaminant is a particular focus here.

ISO 14687 (DIN EN 17124) specifies strict limit values for 13 different substances/contaminants (excluding particles) for hydrogen used in fuel cells. The current limit for water is 5 ppm. Measurements by the ZBT at more than 20 filling stations show that water regularly occurs in concentrations that reach or exceed this value. This has an impact on the reliability and safety of the systems, for example due to condensation and freezing in pipes, storage tanks or fittings.

The investigations have also shown that the water distribution in the system is heavily dependent on pressure, temperature and operating strategy and that the values measured at the discharge point often only represent a snapshot. A comprehensive understanding of the dynamic processes is therefore necessary. Therefore, the HRS model is extended by the possibility to perform calculations with wet hydrogen in order to analyse the time- and location-resolved distribution of water in filling systems so that condensation, dew point shifts and enrichment processes can be determined. In other words, the gaseous loading of hydrogen with water is represented. In this way, accumulation and precipitation points as well as critical operating points can be identified and recommendations for action can be derived.

The HRS model developed in the previous project enables the mapping of central thermodynamic processes in a hydrogen filling plant. The tool built in MATLAB/Simulink was validated with data from the hydrogen test field at the ZBT.

With HRS Model II, this approach is expanded to include the following options and functions:

• Energy and economic assessment: A module is added that shows the trade-off between investment costs (CAPEX) and operating costs (OPEX) and thus enables a holistic optimisation of systems.
• Validation with practical data: In addition to measurements on the test field, data from real systems from industrial partners is integrated in order to check the simulations in a practical manner.

The project is funded by the BMWK as part of the Industrial Collective Research (IGF) and started on 01.04.2025 with a duration of 30 months. It is supported by a project committee comprising over 25 members and is still open to new partners.

The knowledge gained is not only used in scientific publications, but is also incorporated into industry and standardisation in a targeted manner. The updated HRS model will continue to be made available free of charge and licence-free via hrs-modell.de.