1 How to provide high amount of EGR in diesel engines while maintaining low engine fuel consumption?...

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How to provide high amount of EGR in diesel engines while maintaining

low engine fuel consumption?

Preliminary (short) litterature survey.Eric Ollivier

CICERO meeting, 07/02/16

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NOx fuel consumption trade-offs

From MTZ, 07/01 : Correlation between emissions reduction and fuel consumption in passenger car DI diesel engines (study supported by FFV workgroup) [4].

Injection (pressure,timing, strategy …)

Intensified EGR cooling

US 07 NOx-Scenarios

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Scania´s strategy for NOx emissions reduction

Emissions control techniques on Scania’s current range of truck engines (from www. greencarcongress.com , www.scania.com)

EGR : - Euro 4 : 18% of EGR , Euro 5 : 25% of EGR

- Non Turbocompound engines : Venturi valve (suction effect)

- Turbocompound engines : Additional backpressure (No need of venturi valve)

- Fuel consumption of Euro 4 engines comparable to the Euro 3 engines

Euro 5 : High pressure injection system : Scania XPI

US 07 ?

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MAN´s strategy for NOx emissions reduction

Europe : - Euro 4 : EGR + PM catalyst - Euro 5 : EGR + PM catalyst or AdBlue/SCR

(VGT as an alternative to the bypass valve)

wastegate

Low pressure stage turbocharger

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

bypass

US 07 ?

(from www. ae-plus.com , www.man.com)

No additional fuel consumption !

Fuel consumption ?

Air charge cooler

High pressure stage turbocharger

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US EPA 07 : - EGR + Diesel Particles Filter - On Volvo D11, D13 and D16

Volvo´s strategy for NOx emissions reduction

Resulting fuel consumption ?

(from www. greencarcongress.com)

Europe : - Exhaust gas aftertreatment with AdBlue/SCR catalyst cleaning (followed in this way by Daimler-Chrysler) - Euro 4 : 3-4% AdBlue , Euro 5 : 5-7% AdBlue - EGR not given up

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- EGR circuit compound (2) - Advanced turbocharging system (5)- EGR / VGT control systems (8)- Advanced turbocharging systems + EGR circuit compounds (2)- Others (3)

SAE Papers (1999-2006) :

(High EGR rate)

US 07 NOx - Scenarios

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EGR circuit compound :

Advantages :-The EGR can be cooled twice- P4 > P1

Drawbacks- Low response time - Condensation & fouling

Low pressure loop :

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High pressure loop :

EGR circuit compound :

Advantages :

- No condensation and fouling

Drawbacks :- High charge inlet temperature- P2 can be higher than P3

- Coordination of EGR valve/VGT vanes

High or Low pressure loop? -17 papers : 17 HP loops , 2 LP loops

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EGR circuit compound :

Increase in EGR mass flow by a EGR route with reduced pressure drop (Bushwald et al. 2006)

Effect of pressure losses on EGR rate :

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EGR circuit compound :

Effect of charge cooling on EGR rate : Tin = 40ºC, required cooling power < 20 kW

Charge inlet temperature for a EU4 base engine,VNT TC, HP-EGR. (Bushawald et al., 2006)

Increase of EGR rate at constant A/F-ratio through a modified charge air and EGR cooling system; Reference EU4 base engine (Buchwald et al., 2006)

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EGR circuit compound :

Effect of EGR temperature on charge temperature and volumetric efficiency :(Serrano et al., 2005)

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Advanced turbocharging system :

Virtual turbocharging system enabling to reach sufficient amount of EGR to fulfill Euro 5 (Langridge et al. , 2002)

Compressor Efficiency : 77%Turbine Efficiency : 75%

Required amount of EGR 20%

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Advanced turbocharging system :

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

2 radial compressor wheels in series

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Advanced turbocharging system :

Performance of the LST compressor stage against thestate of the art single stage compressor (Arnold, 2004)

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Advanced turbocharging system :

Intermediate EGR route, (Arnold 2004)

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Advanced turbocharging system :

Compressor, turbine and oerall turbo efficiency at full load against engine speed, (Arnold 2004)

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Advanced turbocharging system :

New turbocharging strategies to reach EURO 5 :

Study of a 2 stage turbocharging system very similar to MAN-BorgWarner R2S by (Buchwald et al., 2006)

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

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Advanced turbocharging system :

New turbocharging strategies to reach EURO 5 : 2 stage turbocharging system

Full load compressor map

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Advanced turbocharging system :

New turbocharging strategies to reach EURO 5 : 2 stage turbocharging system

Full load characteristics of the engine

90%

25%

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Advanced turbocharging system :

New turbocharging strategies to reach EURO 5 : 2 stage turbocharging system

Maximum overall TC efficiency for the 2 stage TC and the VNT TC at maximum EGR (Buchwald et al., 2006)

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Advanced turbocharging system :

New turbocharging strategies to reach EURO 5 : 2 stage turbocharging system

Results in transient modes

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High amount of EGR :- To limit the amount of O2 in the combustion chamber- Increase the heat capacity of the mixture

High efficiency cooling device : -Increase the density and the temperature of the Air/EGR mixture

Results in : - Low combustion temperature and significant NOx emission reduction - Increase PM - Slight increase of consumption

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Eu4

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Emission Standards for HD Diesel Engines

CO HC NOx PM Smoke

Euro IV (2005)

1,5 g/kWh

0,46 g/kWh

3,5 g/kWh

0,02 g/kWh 0,5 (m-1)

Euro V (2008)

1,5 g/kWh

0,46 g/kWh

2,0 g/kWh

0,02 g/kWh 0,5 (m-1)

US 07(2007)

1,5 g/kWh

0,13 g/kWh

US 10(2010)

0,012 g/kwh