Experimental results of hydrogen enrichment of ethanol in an ultra-lean internal combustion engine

It was shown that hydrogen enrichment of ethanol demonstrated an ability to reduce NOx and stabilize and accelerate the combustion process. The experiments showed that operating near the LOL at both 15% and 30% hydrogen by volume reduced engine out NOx emissions by more than 95% as compared to stoichiometric gasoline operation. This reduction is comparable to the efficiency of modern three-way catalyst and could offer an alternative to current NOx reduction technologies. Power, thermal efficiency, and volumetric efficiency were not affected by the hydrogen mixture at a given equivalence ratio. However, hydrogen addition allowed an increase in the lean operating limit which helped further reduce NOx emissions, but also at reduced power and thermal efficiency.