Study on the Effect of Ozone on Diesel Engine Exhaust NOx Emission

SCR is one of the best after treatment technology for de-NOx in automotive diesel engines. However, due to the sea water scrubbing desulfurization in marine diesel engines, the exhaust gas leads to a significant decrease in exhaust gas temperature, so SCR technology for vehicles cannot be directly transferred to marine diesel engines. This work conducted a bench test to test the exhaust emissions of a diesel engine by adding ozone to the exhaust gas under conditions of both low load and idling. The results showed that when the exhaust gas temperature was above180 ℃, NOx increased with a maximum increase of 93.14% due to the ozone decomposition. When the gas temperature was below 100 ℃, ozone oxidized part of NO to NO2. The O3/NO molar ratio had a greater effect on the NOx emissions of diesel engines. As the O3/NO molar ratio was close to 1, the NO oxidation effect was the best and the de-NOx efficiency reached 79.31%. Under low temperature operating conditions, O3 is effective in reducing NOx emissions from the exhaust of marine diesel engines.