Transient Operation of Hydrogen Engines

Authors

Dr. techn. P. Grabner, Dipl.-Ing. P. Christoforetti, Dipl.-Ing. K. Gschiel, Dipl.-Ing. S. Roiser, Univ.-Prof. Dr. techn. H. Eichlseder, Institute of Thermodynamics and Sustainable Propulsion Systems, Graz University of Technology:

Year

2023

Print Info

Production/Publication ÖVK

Summary

To meet future challenges from climate change, CO₂ savings in the mobile sector are absolutely essential. The use of an internal combustion engine as an energy converter for green hydrogen into mechanical energy is one possibility for this. During the combustion of hydrogen in the engine, nitrogen oxides are the significantly relevant pollutant component, the emission of NO_x strongly depends on the operating strategy. With lean-burn combustion processes, lowest nitrogen oxide emissions can be achieved with excellent efficiencies at steady-state operating points. The challenge lies in optimizing the operating strategy for transient operation in order to achieve excellent emissions here as well.

Extensive experimental investigations were carried out to develop a transient operating strategy for lean-burn processes, basing on previous findings on the emission behavior of hydrogen engines. The high boost pressures required for the lean air fuel ratios pose a challenge in the interaction between dynamics and pollutant emissions. To ensure sufficient dynamics while meeting emission requirements, three measures were investigated in more detail.

Using newly developed or adapted ECU software that makes use of various elements from gasoline and diesel engine control systems, investigations were carried out on the engine test bench with regard to transient behavior. By applying acceleration enrichment, ignition retardation and post-injection in an emulated WLTC, raw emission values below the proposed Euro 7 tailpipe limits were achieved. Significant NO_x reductions can also be achieved by means of water injection. In addition, the use of an electrically driven compressor (e-charger) offers further potential, especially for very dynamic load requirements.

ISBN

978-3-9504969-2-5