Experiments on Hydrogen Engine Exhaust After-Treatment Systems

Report, 2025

A commercial grade exhaust after treatment system (EATS) was fitted to a hydrogen fueled, heavy-duty research engine, to investigate the effects of some of the unique properties of hydrogen engine exhaust, especially the high water concentration,  on the function of a conventional EATS. A design of experiments approach was used to determine the range the impact of the most influential changes in engine operating parameters on the engine out emissions, mainly nitrogen oxides and particulates, and the impact on a standard diesel oxidizing catalyst. Finally, several experiments were run investigating the functionality of a copper-zeolite selective catalytic reduction (SCR) system at high water concentrations.

The results show that it is possible to reduce the emissions of nitrogen oxides with a conventional SCR system. However the strong correlation between the nitrogen oxide emissions and the water concentration in the exhaust gases made it impossible to separate the effect of the two on the performance of the system.