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

2 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

3 Scania´s strategy for NOx emissions reduction Emissions control techniques on Scania’s current range of truck engines (from www. greencarcongress.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 ?

4 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, No additional fuel consumption ! Fuel consumption ? Air charge cooler High pressure stage turbocharger

5 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

6 - EGR circuit compound (2) - Advanced turbocharging system (5) - EGR / VGT control systems (8) - Advanced turbocharging systems + EGR circuit compounds (2) - Others (3) SAE Papers ( ) : (High EGR rate) US 07 NOx - Scenarios

7 EGR circuit compound : Advantages : -The EGR can be cooled twice - P 4 > P 1 Drawbacks - Low response time - Condensation & fouling Low pressure loop :

8 High pressure loop : EGR circuit compound : Advantages : - No condensation and fouling Drawbacks : - High charge inlet temperature - P 2 can be higher than P 3 - Coordination of EGR valve/VGT vanes High or Low pressure loop? -17 papers : 17 HP loops, 2 LP loops

9 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 :

10 EGR circuit compound : Effect of charge cooling on EGR rate : T in = 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)

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

12 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%

13 Advanced turbocharging system : The Low speed turbo by Garett Engine boosting System (S. Arnold, 2004) 2 radial compressor wheels in series

14 Advanced turbocharging system : Performance of the LST compressor stage against the state of the art single stage compressor (Arnold, 2004)

15 Advanced turbocharging system : Intermediate EGR route, (Arnold 2004)

16 Advanced turbocharging system : Compressor, turbine and oerall turbo efficiency at full load against engine speed, (Arnold 2004)

17 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%

18 Advanced turbocharging system : New turbocharging strategies to reach EURO 5 : 2 stage turbocharging system Full load compressor map

19 Advanced turbocharging system : New turbocharging strategies to reach EURO 5 : 2 stage turbocharging system Full load characteristics of the engine 90% 25%

20 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)

21 Advanced turbocharging system : New turbocharging strategies to reach EURO 5 : 2 stage turbocharging system Results in transient modes

22 High amount of EGR : - To limit the amount of O 2 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

23 Eu4

24 Emission Standards for HD Diesel Engines COHCNOxPMSmoke Euro IV (2005) 1,5 g/kWh 0,46 g/kWh 3,5 g/kWh 0,02 g/kWh0,5 (m-1) Euro V (2008) 1,5 g/kWh 0,46 g/kWh 2,0 g/kWh 0,02 g/kWh0,5 (m-1) US 07 (2007) 1,5 g/kWh 0,13 g/kWh US 10 (2010) 0,012 g/kwh