HyDISI - Near-zero Emission Concept for H2 DI Otto Engines en

The hydrogen engine can make an important contribution to achieving global climate targets. Particularly in long-distance and heavy-duty transport as well as in mobile machinery, hydrogen engines may represent an alternative in the future due to the requirements regarding range, performance and robustness.

Three university research institutions are collaborating on this FVV-funded project. Together with RWTH Aachen and the University of Stuttgart, work is being done on optimizing the hydrogen combustion engine. Our institute is mainly dealing with the topics of combustion process optimization and exhaust gas aftertreatment on an experimental basis. These investigations are carried out on a full passenger car engine that has been upgraded for hydrogen operation. Components such as the injection system, ignition, turbocharging, crankcase ventilation, etc. had to be adapted for hydrogen operation.

A major challenge in hydrogen combustion optimization is the avoidance of abnormal combustion. Very lean operation provides a good basis here, but requires an extremely efficient turbocharging system, especially in highly dynamic operation. Issues such as residual discharges from the ignition system, engine oil-related deposits, hot components or particles in the combustion chamber play a central role in the development of combustion anomalies and should therefore be avoided wherever possible. The figure below shows a preignition induced by residual discharge of the ignition coil (red curves). These anomalies could be reliably eliminated by making hardware adjustments to the ignition coil.

The subject of exhaust gas aftertreatment is also being intensively investigated. In particular, the behavior of different exhaust aftertreatment concepts (OC, SCR, NSC, ASC, PF) was evaluated in different designs (coatings, volumes, order of arrangement) in relevant driving cycles (WLTC, defensive/aggressive RDE, etc.) on the engine test bench. The figure below shows both the raw NOx emissions and the NOx emissions after exhaust aftertreatment for a WLTC. With the executed system, very low tailpipe NOx (< 10 mg/km) could thus be presented.