An experimental study of EGR and turbocharging concepts has been performed on an experimental 2.0-litre 4-cylinder turbocharged Euro6 light-duty diesel engine. The purpose of the study was to investigate the emissions and fuel consumption trade-off for different concept combinations.
The impact of low-pressure and high-pressure EGR was studied in terms of engine-out emissions and fuel consumption. Moreover, the influence of single-stage and two-stage turbocharging was investigated in combination with the EGR systems, and how the engine efficiency could be further improved after engine calibration optimization.
During low load engine operation where throttling may be required to achieve the desired low-pressure EGR rate, the difference in fuel consumption impact was studied for exhaust throttling and intake throttling, respectively.
The cooling impact on high-pressure EGR was compared in terms of emissions and fuel consumption. Finally, an EGR concept for balancing low engine-out emissions in combination with high engine efficiency is proposed.