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Emissions laws drive diesel innovations

01 Jan 2006

EUROPEAN Union regulations setting stringent limits on exhaust emissions from diesel engines used in rail traction will start to come into force on January 1. From now on engines fitted to new diesel railcars or multiple-units must meet Stage 3A of the European emissions limits for off-highway vehicles, while new engines used in locomotives must conform to the regulations from January 2009.

The rules do not apply to existing engines in either railcars or locomotives, but replacement engines must meet the new standards - this applies to new types of engine only and is not intended to mean replacement engines of the same type used to replace a failed unit, for example.

Until now European railways have applied UIC recommendations on emissions, but these are not mandatory. But Directive 97/68/EC and subsequent related rulings will impose increasingly stringent requirements over the coming years.

The rules apply to emission of nitrous oxides (NOx) and soot particles, carbon monoxide and hydrocarbons. For railcars the current limit is 4·0g/kWh for NOx and 0·2g/kWh for soot particles, but from 2012 the NOx limit comes down to 2·0g/kWh, while soot particle emissions must not exceed 0·025g/kWh. For locomotive engines, emission limits from 2009 will depend on the power rating, and from 2012 sulphur-free fuels must be used on diesel locomotives operating throughout the EU.

MTU expects to meet the new rules thanks to a range of design improvements, but the soot limit of 0·025g/kWh is not considered attainable without fitting particle filters, which have operational drawbacks. In November the company announced that it was working on the design of a high-performance 12-cylinder engine with a nominal rating of nearly 5000 kW that will meet the permissible emission limits for locomotives - this is destined for six-axle heavy freight locomotives. Options for engines with filters will be available, as already applied to engines such as the 20V 4000R42 fitted to a Vossloh-built Mak2000-4 locomotive unveiled at the InnoTrans event in 2004.

Reducing NOx emissions may prove more difficult. At the moment complaints can be filed by the general public over soot particle emissions, and from 2010 in Germany this will apply to NOx emissions too.

Low-emission engine designs take shape

LEGISLATION in the European Union and in the USA is forcing the pace of diesel engine development so that future products emit cleaner exhaust gases. Friedrichshafen based MTU is developing engines for both the locomotive and railcar/DMU market.

Most advanced is the R43 version of its 4000 series for locomotive applications. Building on experience with its R41 and R42 designs that have already won plaudits for low emissions, MTU plans to start testing the R43 in mid-2006 with a view to series production from autumn 2008.

Rated at 1800 kW at a nominal speed of 800 rev/min, the R43 is a compact 12-cylinder design intended to meet the emissions standards that will apply in 2009; these specify a NOx limit of 7·4g/kWh and 0·2g/kWh for soot particles. Turbocharging, an optimised cooling system, a common rail injection system and MTU's Advanced Diesel Engine Control are design features that will help ensure compatibility with exhaust gas limits and contribute to low noise emissions and low fuel consumption. Weight to power ratio will rise from 3·3 kg/kW on the earlier designs to 3·7 kg/kW. A particle filter can be fitted as an option. Dimensions will remain unchanged from earlier 4000 series engines so that the new design can be easily fitted as a replacement.

MTU has also announced the development of a low-emission engine for the diesel railcar market. The 1600 series remained on the drawing board until November, when the company gave the go-ahead for the design to be commercialised, securing jobs at the Friedrichshafen factory. The 1600 series will be developed from a lorry engine in two versions nominally rated at 550 kW and 660 kW. As the engine will be mounted underfloor, height has been kept to 800 mm, ensuring that it can also be used to replace older designs.