7 December 2006 (Update 2)
Scania announced it will start introducing its new Euro V truck engine platform utilizing exhaust gas recirculation (EGR) during 2007. These will be the first heavy-duty diesel engines meeting the Euro V standards (NOx = 2 g/kWh, PM = 0.02 g/kWh) without the use of selective catalytic reduction (SCR) technology.
Scania has traditionally favored in-cylinder emission control over aftertreatment strategies. Scania was the first manufacturer to introduce Euro IV engines with EGR. However, due to such issues as heat dissipation problems from EGR cooling, urea-SCR was used in larger Euro IV units (16-liter), as well as in Scania Euro V engines (16- and 12-liter).
Few technical details were given on the Euro V EGR system. According to earlier reports, Scania EGR system would use EGR rates of up to 18% in Euro IV, and up to 25% in Euro V engines, and the EGR flow was driven by a venturi.
PM emissions are controlled in Scania engines through in-cylinder strategies, without the use of particulate filters. The existing Euro IV EGR engines also use a diesel oxidation catalyst (DOC) to provide further reductions in PM emissions and diesel smell. The new EGR engines will meet the Euro V standards without any aftertreatment, not even the DOC.
The key to the in-cylinder emission control is the Scania XPI common-rail injection system developed jointly with Cummins. Its high injection pressures (2400 bar) are available at all times, independently from the camshaft, offering the liberty of tailoring pre- and post-injections depending on the engine conditions. For five years, Scania engines also use Scania’s own, in-house developed engine management systems.
Urea (AdBlue)-SCR technology was introduced in the European market by DaimlerChrysler in the early 2005 under the trade name BlueTec. Euro IV/V trucks equipped with SCR have superior fuel economy, as the engine can be calibrated for higher efficiency and higher NOx emissions which are then reduced over the SCR catalyst. The fuel economy advantage, however, is offset to a degree by the cost of urea. Disadvantages of trucks with the SCR technology include the necessity to periodically fill up urea and a reduced payload, due to the need to carry the onboard urea tank, noted Scania.