Combustion, Aftertreatment and Control Key Elements for Emission Reduction of US HSDI Diesel Engines

Transcription

1 Combustion, Aftertreatment and Control Key Elements for Emission Reduction of US HSDI Diesel Engines ERC Symposium, Madison Ulrich Pfahl AVL Powertrain Engineering Plymouth, MI, USA ERC SYMPOSIUM June 8 th, 2005 Page - 1

2 Content Introduction Combustion Low NOx Strategy Low Load Low NOx Strategy High Load Aftertreatment Control Summary ERC SYMPOSIUM June 8 th, 2005 Page - 2

3 LD FTP 75 & US 06 and HD emission limits / certification targets 0,1 TPM - g/kg fuel 0,09 0,08 0,07 0,06 0,05 0,04 0,03 0,02 US 06 0,14 PC SUV Due to high speed & load operation extremely difficult to achieve 0,25 0,4 0,6 gpm Full Size Pick Up FTP PC FTP Mid Size SUV 2007 Full Size Pick Up 2010 Full Size Pick Up US 06 0, NOx - g/kg fuel ERC SYMPOSIUM June 8 th, 2005 Page - 3

4 Spec. Power vs. Peak Firing Pressure Speed Range: rpm / Displacement per Cyl.: L Passenger car / LCV / SUV 65 Spec. Power [kw/l] Base Variant Small HSDI =16.5 FIE 1800 bar Piezo Swirl Modulation Small HSDI 17.5 FIE 1600 bar Solenoid Swirl fixed Peak Firing Pressure [bar] ERC SYMPOSIUM June 8 th, 2005 Page - 4

5 Compression Ratio Peak Firing Pressure - bar Baseline ~17,5:1 T Exhaust ~780 C Development trend ~16.5:1 T Exhaust ~820 C Rated Specific Power - kw/l PFP Reduction 90 ERC SYMPOSIUM June 8 th, 2005 Page - 5

6 Combustion Low NOx Strategy Low Load Area ERC SYMPOSIUM June 8 th, 2005 Page - 6

7 Area of Alternative Combustion VTG and Standard FIE Load bar Optimised Standard Combustion 4 2 Alternative Combustion HCLI, frühe Einspritzung 90196b Speed RPM 3500 ERC SYMPOSIUM June 8 th, 2005 Page - 7

8 Potential and Challenge of Alternative Combustion Multicylinder engine (~0.5L/Cyl Class); 1500 rpm; 15% load % -3% -93% -76% % Conventional Combustion Alternative Combustion BSFC NOx Soot % +350% HC CO ERC SYMPOSIUM June 8 th, 2005 Page - 8

9 Alternative Combustion Emissions in Urban Cycle Part Multicylinder engine (~0.5L/Cyl Class) with Cylinder pressure guided Closed loop combustion control Conventional Combustion Alternative Combustion NOx Opacity ERC SYMPOSIUM June 8 th, 2005 Page - 9

10 Combustion Low NOx Strategy Higher Load Area ERC SYMPOSIUM June 8 th, 2005 Page - 10

11 Emission reduction with higher EGR Rates at increased boost pressures 2000 rpm; 45 mm3/stroke;swirl/intake temperature=const; Boost pressure/rail pressure/soi/egr-rate=variable; 0,7 bar 0.7 bar Relative Relative boost boost pressure pressure 1,9 bar 1.9 bar 50 EGR AGR Abgasrückführrate EGR Rate [%] [%] Emissionen Emissions pro Zylinder [g/h] [g/h] Soot RUSS AGR EGR NOX Soot RUSS NOX 0 1,1 1,2 1,3 1,4 1,5 1,6 1,7 Lambda [-] ERC SYMPOSIUM June 8 th, 2005 Page - 11

12 NOx, Soot - g/h Effect of part load boosting on EGR, NOx and Soot at const. SCRE* test results NOx Soot EGR 2000rpm; IMEP=8bar; =1,4; Displ 0,533L Swirl / T intake / P rail / SOI Pilot & Main =const EGR - % ,4 0,6 0,8 1 1,2 1,4 cylinder Relative Intake Pressure - bar *) SCRE: single cylinder research engine ERC SYMPOSIUM June 8 th, 2005 Page - 12

13 Boosting Concepts 2,40 ~2000 RPM, ~50% Load 2,20 2,00 Lambda 1,80 1,60 1,40 Base VTG Small VTG 2-stage TC or VTG with VGC NOx -35% 1,20 1, EGR-Rate - % ERC SYMPOSIUM June 8 th, 2005 Page - 13

14 Boosting helps to improve emissions 12 SCRE* 0,5L/Cyl Class, 2000rpm, IMEP=13 bar, T intake =const 10 Soot - g/kg fuel Increasing Rail Pressure Increasing EGR-Rate *) SCRE: single cylinder research engine Increasing Boost Pressure NOx - g/kg fuel Basis ERC SYMPOSIUM June 8 th, 2005 Page - 14

15 Increase of EGR and Rail pressure RAIL [bar] NOXS [g/kg] rpm - V FUELSTR = 45mm 3 /str Increase of EGR and Railpressure 6-hole Nozzle 1,1 1,0 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0,0 SOOT [g/kg] Lambda [-] EGR [%] 2,8 2,6 2,4 2,2 2,0 1,8 1, ,9 0,8 0,7 0,6 0,5 0,4 ISFC [g/kwh] HC [g/kg] ERC SYMPOSIUM June 8 th, 2005 Page - 15

16 NOx * Smoke Efficient EGR cooling improves Emission significantly NOx*Smoke=ppm*BSU ~1000 rpm ~ 2 bar ~1600 rpm ~ 4 bar ~1600 rpm ~ 7 bar Exhaust Temperature Drop in EGR Cooler - C ERC SYMPOSIUM June 8 th, 2005 Page - 16

17 Aftertreatment ERC SYMPOSIUM June 8 th, 2005 Page - 17

18 NOx-Catalysts Conversion efficiency 120 NOx - Conversion - % FTP 75 Focal Area US 06 Focal Area Catalyst Temperature - C NOx - Ads 1 NOx - Ads 2 SCR-Cat 4Way - Cat ERC SYMPOSIUM June 8 th, 2005 Page - 18

19 Durability performance of aftertreatment technologies 100 Conversion - % DPF UREA SCR NOx Adsorber Driving Distance - miles ERC SYMPOSIUM June 8 th, 2005 Page - 19

20 Exhaust Aftertreatment for HSDI Diesel DPF (> 90 % < 99%) PM Mass/Number Reduction DPF as must for future NOx Reduction Separator (> 40% < 50%) UREA SCR NOx adsorber NOx application scenario: If > 55 / 60% after miles, then SCR. However EPA, Infrastructure and some OEM s reluctance If < 50% after miles then NOx-Adsorber. However yet not proven ERC SYMPOSIUM June 8 th, 2005 Page - 20

21 The use of EAS and it s type of operation asks for further raw emission reduction NOx increase in % DPF loading time / DPF regeneration time to 10% NOx emission during regeneration / standard NOx emission ERC SYMPOSIUM June 8 th, 2005 Page - 21

22 Control ERC SYMPOSIUM June 8 th, 2005 Page - 22

23 Cylinder Pressure guided EMS Development Environment Calibration PC ETK EMS Start and Duration of Injection (Cyl.1 Cyl.n) (Ethernet) VNT, EGR, Swirl,... EGR-Coolerbypass Actuators ES1000 AFS, RPS, Pedal,... Sensors MFB50% Cyl.1 (CAN) MicroAuto Box Signal- Interface Pressure sensor Charge- Amplifier 60-2 Trigger One Lead-cylinder Example ERC SYMPOSIUM June 8 th, 2005 Page - 23

24 Alternative Combustion. In Vehicle Noise Assessment on Acoustic Chassis Dyno Multicylinder engine (~0.5L/Cyl Class) with Cylinder pressure guided Closed loop combustion control 70 km/h Engine Speed - rpm 100 km/h 120 km/h Time - sec Conventional Combustion Alternative Combustion Sound Pressure - dba Time - sec Sound Pressure - dba 1 khz Frequency - Hz ERC SYMPOSIUM June 8 th, 2005 Page - 24

25 Benefits of Closed Loop Combustion Control Stability over Lifetime (Tolerances, Emissions) Other sensors can be simplified or even deleted Reduced Application effort Enabling highest Power-density (PFP Monitoring) OBD Compensation of Fuel quality influence Torque feedback and control Improved cold-startability and engine warm-up (Monitoring) Enabling new combustion concepts ERC SYMPOSIUM June 8 th, 2005 Page - 25

26 Summary ERC SYMPOSIUM June 8 th, 2005 Page - 26

27 Conclusions For passenger cars the main challenge will be the US06 driving cycle with the high load areas. For heavier SUVs the lower loaded FTP75 will be the main focus, since heavier SUVs have higher NOx limitations in the US06 cycle, while the values for the FTP75 are the same as for PC. Main Fields of Combustion Development: Combustion (Conventional, Alternative) - Charge Management (Boosting, EGR, Charge/EGR Cooling) - Injection (Pressure, Nozzle, Architecture) Control (Model based, Cylinder / Combustion guided, Multivariable Controller, Tolerances, Long Term Stability) DPF will be mandatory. Necessity and definition of NOx aftertreatment dependents on engine / vehicle combination. ERC SYMPOSIUM June 8 th, 2005 Page - 27

28 Thank you for your attention! ERC SYMPOSIUM June 8 th, 2005 Page - 28