Beyond Euro 3 III MAN believes that the combination of
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common-rail fuel injection and cooled EGR will be enough to reduce NOx formation from the Euro-3 level of 5.0g/kWh to the Euro-4 requirement of 3.5g/kWh. But fuel consumption is likely to climb, and after-treatment will be needed to keep particulates low. A CRT system is only practical if it is optimised to the engine and the fuel has an ultra-low sulphur content (less than 0.001%). At Frankfurt MAN will show a CRT system designed for the TO-A range. This will include a pre-catalyst and filter made up of standard automotive modules and fitted into a TG-A exhaust.
The second approach is to use selective catalytic reduction (SCR). The GDK-SINOx system, developed by Siemens, can cut NOx levels by 65% without a large fuel consumption penalty. The problem is that this uses a source of liquid urea which has to be refilled regularly, requiring a new infrastructure. MAN will show a SIN0x-equipped TG-A at IAA, and will fit the first installations to customers' TO 410As next April.
For Euro-5 in 2008 MAN is developing a new version of SCR, with a GD-KAT oxidation catalyst positioned upstream of the SINOx unit to increase NOx conversion to 80% or more. This could be available by 2007, but MAN says that changes in infrastructure and fuel composition "will call for a supreme effort on the part of industry, politicians and authorities".