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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. NOx fuel consumption trade-offs. US 07 NOx-Scenarios. Injection (pressure, timing, strategy …). Intensified EGR
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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
NOx fuel consumption trade-offs US 07 NOx-Scenarios Injection (pressure, timing, strategy …) Intensified EGR cooling From MTZ, 07/01 : Correlation between emissions reduction and fuel consumption in passenger car DI diesel engines (study supported by FFV workgroup) [4].
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) US 07 ? 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
No additional fuel consumption ! Fuel consumption ? Regulated Two-stage Turbocharging System, R2S (on 4 cyl. 4,6L engines, other?) Low pressure stage turbocharger wastegate MAN´s strategy for NOx emissions reduction (from www. ae-plus.com , www.man.com) Europe :-Euro 4 :EGR + PM catalyst - Euro 5 :EGR + PM catalyst or AdBlue/SCR US 07 ? High pressure stage turbocharger Air charge cooler bypass (VGT as an alternative to the bypass valve)
Volvo´s strategy for NOx emissions reduction (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 US EPA 07 :-EGR + Diesel Particles Filter - On Volvo D11, D13 and D16 Resulting fuel consumption ?
(High EGR rate) SAE Papers (1999-2006) : • - EGR circuit compound (2) • Advanced turbocharging system (5) • EGR / VGT control systems (8) • Advanced turbocharging systems + EGR circuit compounds (2) • Others (3) US 07 NOx - Scenarios
EGR circuit compound : Low pressure loop : • Advantages : • The EGR can be cooled twice • P4 > P1 • Drawbacks • Low response time • - Condensation & fouling
EGR circuit compound : High pressure loop : • 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
Increase in EGR mass flow by a EGR route with reduced pressure drop (Bushwald et al. 2006) EGR circuit compound : Effect of pressure losses on EGR rate :
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)
EGR circuit compound : Effect of EGR temperature on charge temperature and volumetric efficiency : (Serrano et al., 2005)
Advanced turbocharging system : Required amount of EGR 20% Compressor Efficiency : 77% Turbine Efficiency : 75% Virtual turbocharging system enabling to reach sufficient amount of EGR to fulfill Euro 5 (Langridge et al. , 2002)
2 radial compressor wheels in series Advanced turbocharging system : The Low speed turbo by Garett Engine boosting System (S. Arnold, 2004)
Advanced turbocharging system : Performance of the LST compressor stage against the state of the art single stage compressor (Arnold, 2004)
Advanced turbocharging system : Intermediate EGR route, (Arnold 2004)
Advanced turbocharging system : Compressor, turbine and oerall turbo efficiency at full load against engine speed, (Arnold 2004)
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= 2 Inlet charge temperature = 40ºC EGR-rate = 60%
Advanced turbocharging system : New turbocharging strategies to reach EURO 5 : 2 stage turbocharging system Full load compressor map
Advanced turbocharging system : New turbocharging strategies to reach EURO 5 : 2 stage turbocharging system 25% 90% Full load characteristics of the engine
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)
Advanced turbocharging system : New turbocharging strategies to reach EURO 5 : 2 stage turbocharging system Results in transient modes
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