Browse Publications Technical Papers 2011-37-0004
2011-06-09

Performance Analysis of a Turbocharged Heavy Duty Diesel Engine with a Pre-turbo Diesel Particulate Filter Configuration 2011-37-0004

The use of particulate filters (DPF) has become in recent years the state of the art technology for the reduction of soot aerosol emissions for light, medium and heavy duty Diesel vehicles. However, the effect of the system location on engine performance is a key aspect that should be studied. In the present work a numerical study has been carried out with the objective to analyze the effect on the engine performance of an innovative DPF placement upstream of the turbine. This study has been performed by means of the gas dynamic simulation of a two-stage turbocharged heavy duty Diesel engine, which has been previously modeled from experimental data obtained under steady state conditions. The original DPF has been divided into two monoliths for the case of the pre-turbo DPF configuration. Three cylinders discharge in each of these monoliths and after the filtration the flow is driven towards the high-pressure turbine and the EGR system.
The engine response is compared with a pre-turbo DPF configuration under steady state conditions against the common DPF placement downstream of the turbine. The study covers a parametric study based on EGR and waste-gate valves opening. It has allowed comparing the variations on the engine operation as function of the EGR rate and the air-to-fuel ratio settings. Different soot loadings have been considered in order to extend the study over a wider range of operating conditions. Finally, the location of the DOC has been also considered as an additional parameter (upstream of the DPF or downstream of the turbines in the pre-turbo configuration).
Results allow identifying the phenomena controlling the engine response when the DPF is placed upstream of the turbines. Among them highlight the increase of the thermal level that favors the passive regeneration, the DPF pressure drop reduction and the benefits that the use of two parallel monoliths brings out regarding the attenuation of the wave interference between cylinders during exhaust valve opening, which leads to make unnecessary the use of twin turbines. The analysis of the interaction among all the involved phenomena provides a comprehensive understanding of the proposed architecture and its potential regarding both the engine and the DPF behavior.

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