Regarding CO2 reduction on commercial vehicles, hydrogen engine is becoming a strong complementary solution, especially for high load profiles. In addition, costs and durability make internal combustion engine a very attractive and effective solution based on current powertrain layouts. The first generation of hydrogen engines follows spark ignited engine combustion processes, which are operated lean with intake manifold or low-pressure direct injection. These concepts have some limitations on the achievable efficiencies and power densities. To achieve significant increase in efficiency, an alternative combustion process close to diesel combustion is required. That demands hydrogen to be injected under high pressure near top dead center. The available or necessary approaches to initiate the diffusion combustion of the hydrogen are also discussed to show path to the target of 50% BTE.
Different engine technologies will expose Hydrogen in different levels, which can create concern of embrittlement. Hydrogen embrittlement is caused by two main mechanisms: high pressure and temperature exposure or high corrosion. In a Hydrogen combustion engine, the key mechanism is high pressure exposure. Hydrogen penetration mechanisms are related to voids and soft materials where it positions on the grain boundaries. Cast irons are favorable to resist embrittlement due to the high number of graphites, serving as an accommodation to hydrogen, delaying embrittlement effect. The shape of graphites and different alloy elements will play an important role on embrittlement resistance combined to the mechanical and fatigue resistance, also necessary on such highly efficient engines. Bench tests and measurements in parallel to dyno evaluations are presented to support the alloy development.
Resistant Cast Iron for a 50% Efficient Hydrogen Engine
Proceedings
Internationaler Motorenkongress ; 2024 ; baden-baden, Deutschland April 19, 2024 - April 29, 2024
2024-07-01
9 pages
Article/Chapter (Book)
Electronic Resource
German
Microstructure of cast iron resistant to hydrogen embrittlement
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