1

New gas exchange system to provide high amount of EGR in DI diesel engines – A preliminary literature

survey.

Eric Ollivier

07/06/05

2

NOx fuel consumption trade-offs

Injection (pressure,Multi-hole nozzle, strategy …)

Intensified EGR cooling

US 07 NOx-Scenarios

CICERO EGR project

Correlation between emissions reduction and fuel consumption in passenger car DI diesel engines (study supported by FFV workgroup) [Lamping et al., MTZ, 07/01 ].

Intensified EGR cooling

3

Required increase of boost pressure to implement 10% EGR at a constant speed [Arnold, 2004].

4

• Positive pressure differential between turbine outlet and compressor inlet

• DPF

•Two stages of cooling : less EGR needed

• Condensation : liquid water and lubricating oil, and acid solution in the intake area

• Big intake volume : homogeneous mixture but high response time

The Low Pressure EGR circuit :

5

• Negative pressure differential between turbine outlet and compressor outlet • Fouling of the EGR cooler • Coordination of EGR valve/VGT vanes

The High Pressure EGR circuit :

6

Thermodynamic comparison of the LP and HP EGR loops :

Reduced Mass Flow as a function of the compressor pressure ratio, in HP and LP EGR loop to provide 30% EGR at 2500 rpm and

12 bar BMEP [Weber et al., 2005]

Passenger car, specific output power of 50kwk/l

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Lambda maps :

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PMEP maps :

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BSFC maps :

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Operating points on the compressor map for 100% load and 1.7λ for HPL and LPL of a Euro III – Euro IV engine (Langridge and Flesser, 2002)

Commercial Vehicle engine, 400kW @ 1900 rpm

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HPL EGR LPL EGR

100% load, 1.7 Air Excess, 80% rated speed 100% load, 1.7 Air Excess, 80% rated speed

BSFC/NOx trade-off for 100% load, 80% rated speed and 1.7 air excess ratio for HPL and LPL (Langridge and Flesser, 2002)

Commercial Vehicle engine, 400kW @ 1900 rpm

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Virtual turbocharging system enabling to reach sufficient amount of EGR to fulfill Euro 5 (Langridge and Flesser, 2002)

Compressor Efficiency : 77% Turbine Efficiency : 75%

Required amount of EGR : 20%

Commercial Vehicle engine, 400kW @ 1900 rpm

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(VGT as an alternative to the wastegate)

bypass

Low pressure stage turbocharger

Regulated Two-stage Turbocharging System, R2S (on 4 cyl. 4,6L engines, other?)

Air charge cooler

bypass

High pressure stage turbocharger

Two stage turbocharging systems (Buchwald et al., 2006)

Alternative, promising , future turbocharging systems to implement high amount of EGR:

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Two stage turbocharging compressor map enabling to reach sufficient amount of EGR to fulfill Euro 5 (Langridge and

Flesser, 2002)

Commercial Vehicle engine, 400kW @ 1900 rpm

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Full load characteristics of the engine

Aim : combustion lambda λc= 2Inlet charge temperature = 40ºCEGR-rate = 60%

Two stage turbocharging systems (Buchwald et al., 2006)

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2 radial compressor wheels in series

The Low speed turbo by Garett Engine boosting System (S. Arnold, 2004)

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Performance of the LST compressor stage against the state of the art single stage compressor

(Arnold, 2004)

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Intermediate EGR route, (Arnold 2004)

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Testing & calculation database

Experience,know how Bibliographic

Research

Ideas

Think-Tank

N Configurations

Numerical Calculations

Selection of the more promising configurations

SimulationsFor refining?

1 D Simulation for new EGR circuit configurations

Test bench?

….

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Full load compressor map

Aim : combustion lambda λc= 2Inlet charge temperature = 40ºCEGR-rate = 60%

Two stage turbocharging systems (Buchwald et al., 2006)