The effect of Exhaust Gas Recirculation (EGR) on the emission from a lean-burner gas engine

The project should demonstrate an indirect effect of EGR on the content of total unburned hydrocarbons (THC) in the exhaust gases from a lean-burn natural gas engine.

When running a specific engine on lower air excess (without EGR), it is known that the THC content in the exhaust gases is often lower compared to the THC content when running the engine on higher air excess. On the other hand, nitric oxides will increase rapidly at decreased air excess. The formation of nitric oxides can be suppressed by the use of EGR.