Skip to main content
European Commission logo

The reduction of NOx emissions in internal combustion engines with high re-circulating ratio of exhaust gases

Italy Flag
Complete with results
Geo-spatial type
Network corridors
Project website
STRIA Roadmaps
Vehicle design and manufacturing (VDM)
Transport mode
Road icon
Transport policies
Environmental/Emissions aspects
Transport sectors
Passenger transport,
Freight transport


Background & Policy context

The EURO IV legislation previously in force fixed the extent of 250 mg / km emission limit for oxides of nitrogen. It was expected that the Euro V standard, in force from January 1, 2009, would conduct this limit to 180 mg / km, a decrease of 28%. By postponing the time horizon to 2012, the time of introduction of the standard EURO VI, it was agreed that the reduction of emissions in question would refer to 80 mg/km, with variations of 55% compared to 2009 and by as much as 68% compared to the previous conditions.

The automotive industry can act both on NOx production process or on exhausted gas treatment.


The goal of the research project can be summarized as: "The reduction in fuel consumption and emissions, with particular reference to the nitrogen oxides (NOx), in Internal Combustion Engines (ICE) used in the field of Mobility."

The general theme, albeit of great interest for the scientific community and the motorsport and automotive industries, needed a degree of specialization that made it compatible with the spirit of the proposed activities of the PRIN.

The project proposed concerned the introduction of new technologies in a consolidated practice of efficacy and already applied in existing engines, represented by recirculation of the exhaust gas (Exhaust Gas Recirculation - EGR), with high ratios of recirculation, even higher than 50% of the mass flow drawn in by the engine.


The most important partial objectives to be pursued to achieve the common objective of the research program were:

  • Verification of the ability to feed the engine with high amounts of exhaust gas recirculated according to a Long Route scheme with levy downstream of the turbine and mixing with the air upstream of the compressor.
  • Evaluation of the stability of the changed operating conditions of the supercharge assembly, which processed, in the presence of high amounts of recirculated gases, flow rates that differed significantly in mass and in thermodynamic conditions from the usual conditions;
  • Verification of the stability of combustion in the presence of loads highly diluted by the residual fraction.


Parent Programmes
Institution Type
Public institution
Institution Name
Ministry of Research (Ministero della Ricerca)
Type of funding
Public (national/regional/local)


The project achieved the following results:

  • The definition of a class of models for the description of dynamic phenomena in the ducts;
  • Mapping of new management situations of the engine overcharging group;
  • The definition of rules for the management of the recirculation flow along the branch that connects the exhaust of the turbine with the suction’s side of the compressor.

The application potential of the results of this research program were related to the identification of technological solutions for the long-route recirculation, low-pressure, high quantities of exhaust gas, in order to respect the impositions of future EURO standards V.


Lead Organisation
EU Contribution
Partner Organisations
EU Contribution


Contribute! Submit your project

Do you wish to submit a project or a programme? Head over to the Contribute page, login and follow the process!