Future for All? – Lambda-1-Combustion Systems of Small Powertrains for the High Volume Market

Authors

Dr.-Ing. Claus Glahn, Dipl.-Ing. Achim Koenigstein, Dr.-Ing. Ingo Hermann,
Opel Automobile GmbH, Ruesselsheim

Summary

Future emission requirements will become increasingly challenging and will demand stoichiometric operation across nearly the full engine map. This current paper shows that stoichiometric operation is limited by the exhaust gas temperature and will limit the maximum specific output. Technical measures to expand the area where the engine can be operated stoichiometrically and such increase maximum specific output will be discussed. On the one hand, there are passive measures either to reduce the exhaust gas temperature by cooling (integrated exhaust manifold, water-cooled turbine housing) or to sustain higher exhaust gas temperatures by the implementation of hightemperature materials for the turbocharger. On the other hand, there are active measures which reduce exhaust gas temperatures by a more efficient combustion.
The active methods range from optimized engine integration boundary conditions, over turbocharger technology, Miller cycle combustion process to cooled exhaust gas recirculation (EGR), water injection and variable compression ratio (VCR). Special
attention is also paid to system cost which has major importance for the cost sensitive A, B and C vehicle segment. An optimized integration in combination with Miller cycle and variable turbine geometry (VTG) represents the most cost effective solution which
allows a stoichiometric power density up to 85 kW/l.

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