Influence of Hybrid Operation on Fuel Consumption and Emissions for Micro-, Mild- and Strong-Hybrid Diesel Applications

Authors

Prof. A. E. Catania, Prof. E. Spessa, Politecnico di Torino; Dr. V. Paladini, Dr. A. Vassallo, General Motors Powertrain Europe, Turin

Year

2008

Print Info

Fortschritt-Berichte VDI, Reihe 12, Nr. 672

Summary

The present paper deals with the experimental activities and the results achieved under a cooperative research project between GM Powertrain Europe and Politecnico di Torino focused on diesel-engine-based hybrid powertrains. The activity assessed experimentally the potentialities in terms of fuel consumption reduction and the challenges in terms of pollutant emissions of micro-, mild- and strong-hybrid diesel applications for light-duty vehicles based on GM 1.9L 4-cyl in-line diesel engine. Engine operation at the dynamic test bench reproduced the optimized hybrid schedules and the results were compared to the conventional base engine. Major results showed that fuel consumption benefits of hybridization could be relevant also in combination with the most efficient ICE powertrain, i.e. the diesel engine coupled with mechanical transmission. As a matter of fact, microhybridization (i.e. Stop/Start system) reduced FC by roughly 4%, mild-hybridization (i.e. Belt Alternator Starter) by roughly 10%, whereas strong-hybridization (i.e. Full-Hybrid Power Split) by roughly 14%. Tailpipe emissions were also influenced by hybridization and showed distinct behaviours with regards to the pollutant species and the system considered. In particular, HC and CO exhibited a general improvements due to the decrease of engine idling time, whereas, only for strong-hybrid, NOx and PM showed increases that required a specific engine recalibration for meeting the same emissions certification of the base engine. This confirmed that hybridization, in particular for stronghybrids, is not a plug and play solution for a certain base engine, but needs to be incorporated in the engine design not only in terms of packaging and durability, which is quite obvious, but also in the base engine thermodynamic set-up (combustion system, EGR circuit and charging, calibration) which need to be optimized for different operation points with respect to the base engine.

Order Members Login