Experimental study of a HD diesel engine equipped with Urea-SCR system able to achieve the Euro IV emission limits

Diesel engines are the most commonly used in public transportations and power plant of freight in the world due to its excellent fuel economy benefit. However emission regulations have become more stringent as a result of increased environmental awareness in each region of the world. In order to meet the Euro IV heavy-duty diesel emission standard legislation limits, a diesel engine can be optimized by internal means to give low particulate emissions and lower fuel consumption. These modifications of the engine lead inevitably to higher NOx emissions due to the NOx/PM trade off. An efficient Urea SCR aftertreatment system is then able to reduce the higher NOx emission to below the Euro IV 3.5g/kWh legislation limit. This paper presents test results obtained by one engine serving in China with an efficient SCR system. The engine had base NOx emission of 8.59g/kWh over the ESC and 8.7g/kWh over the ETC. Outfitted with a urea-SCR catalyst, the engine NOx emission dropped to 2.93g/kWh over the ESC and 2.80g/kWh over the ETC.