1 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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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