Potential of air path variabilities for heavy duty Diesel engines

Authors

Marius Betz, Dávid Kovács, Peter Eilts, Institute of Internal Combustion Engines, Technical University of Braunschweig

Year

2019

Summary

A look at past and current legislation for commercial vehicles indicates a further tightening of future legislation limits. For example, the nitrogen oxide limit values have been reduced from Euro V to Euro VI by 80%. An "Optional Low NOx Standard" is existing in the USA since 2014. Even though this certification is currently still voluntary, the values show clear tendencies. Compared to the current Euro VI standard, NOX emissions are reduced by further 93%. In addition to the reduction of nitrogen oxide emissions, the reduction of greenhouse gases is also further tightened. This is shown by the current US GHG legislation and the CO₂ targets of the European Commission. [1,2,3]
In order to comply with these limits, the engines and exhaust aftertreatment (EAT) concepts of commercial vehicle manufacturers must be continuously further developed. The Miller process, which was originally developed to increase performance, is currently a frequently discussed measure within the engine. The authors' research institute has already carried out work on this method with an electrohydraulic valve train in order to investigate the effects of the Miller cycle at partial and full load. [4, 5, 6, 8]. During this work, significant improvement could be achieved with regard to fuel consumption and emissions at full load, as well as exhaust gas temperature advantages at partial load. Due to the low fuel consumption disadvantage, the temperature increase is seen as an effective method for exhaust gas management [8]. Also a deterioration of the ignition conditions as a potential for the PCCI combustion process could be identified by applying the miller cycle. However, the work was carried out on a single-cylinder test bench,
which makes it difficult to estimate the real potential for the full engine due to the lack of consideration of a turbocharging group and EAT. Therefore, further investigations are required.

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