High-Load Partially Premixed Combustion in a Heavy-Duty Diesel Engine

Home , Car, Compression ratio, Cylinder (engine), Diesel engine

Prof. Bengt Johansson Div. of Combustion Engines, Dept. of Heat and Power Engineering,

DEER, 2005 Outline

• What is a clean engine? • Homogeneous Charge Compression Ignition, HCCI • Partially premixed Combustion, PPC • Optical diagnostics • Summary Clean locally or globally?

Local emissions: NOx HC CO PM

Global emission (Greenhouse effect): CO2 i.e. fuel consumption Environmentally friendly ≡ no CO2? A CO2-neutral alternative? But, some emission statistics from New York by the turn of the century…

• 200 m3 liquid emissions per day • 1000 ton solid emissions per day • An army of tenths of thousands worked with transporting the emissions out from the city Diesel engine emissions? Diesel emissions Diesel engine emissions

• Emissions depends on load • Transient behavior • Post cylinder oxidation important • The engine is not the only scource of emissions – Some PM experts claim tire wear generates 10 times more than the engine Diesel HCCI Emissions vs. diesel

AutoTechnology Oct. 2002, p 54 HCCI

0,01 USA 2007

PM * 0,00 0 0,05 0,5 NOx HCCI with diesel fuel

1. Port fuel injected (classical HCCI) 2. Direct fuel injection (HCCI or PPC) 1. HCCI with port fuel injection First VCR system Multifuel capability Low NOx from HCCI mode 2. Direct fuel injection HCCI Partially premixed combustion, PPC py 6000 1200 • Def: region between truly 5000 1000 homogeneous combustion, HCCI, and diffusion controlled 4000 800 combustion, diesel 3000 600 • Trade-off between NOx and HC, HC [ppm] NOx [ppm] soot typical 2000 400 • Combustion process not well 1000 200 known • Soot the key feature -180 -160 -140 -120 -100 -80 -60 -40 -20 SOI [ATDC] Some experimental results

• Scania single cylinder engine • 1.95 liter displacement • Lowered compression ratio, 12.4:1 • Common Rail fuel injection • Fuel injection pressure 1600 bar • 8, 12 and 15 bar IMEP presented • EGR sweep at constant fuel flow rate • Swedish MK1 diesel fuel 8bar IMEP

500 3.5 2 4 450 NOx HC 3 400 CO 350 soot 2.5 3 300 2 250 1.5 200

150 1 1 soot FSN & CO% NOx /HC as C3 ppm NOx as C3 /HC 100 0.5 50

0 0 30 35 40 45 50 55 60 65 70 75 80 EGR 1 2

3 4 12bar IMEP

800 6 NOx 2 4 700 HC 3 5 CO 600 soot 4 500

400 3

300 1 2 soot CO% & FSN

NOx /HC as C3 ppm 200

1 100

0 0 30 35 40 45 50 55 60 65 70 75 EGR 1 2

3 4 15bar IMEP 3

NOx 2 4 1200 HC 7 CO 1000 soot 6

800 5

4 600

3 400 1 soot FSN & CO% FSN soot

NOx /HC as C3 ppm NOx C3 as /HC 2

200 1

0 0

002 10304EGR050607080 1 2

34 The effect of swirl

• One inlet port deactivated gives twice the swirl

1 High swirl 2

3 4 Swirl effect

Higher Swirl Standard Swirl Lower cetane fuel (CN 21) PPC potential Optical diagnostics to better understand the process 1. Direct imaging of soot 2. Laser induced fluorescence of formaldehyde and OH Optical diagnostics to better understand the process (Soot)

15bar IMEP 3

1200 7 NOx 2 4 HC 1000 CO 6 soot 5 800

4 600 3 400 1

2 soot FSN & CO% NOx /HC as ppm C3 200 1

0 0 0 1020304050607080 EGR Simultaneous OH- and Formaldehyde- LIF Volvo Cars DI diesel Cycle to cycle variations: 12 image-pairs with homogeneous charge The difference between single shot and average image Single

SOI –60ATDC SOI –50ATDC SOI –40ATDC SOI –30ATDC Averag e

SOI –60ATDC SOI –50ATDC SOI –40ATDC SOI –30ATDC Injection strategies

1. HCCI. Port injection

2. HCCI. Injection at 50 CAD BTDC

3. UNIBUS. Injection at 50 CAD BTDC and 3 CAD BTDC

Same IMEP for all conditions, about 1.6 bar 20% EGR Emissions

NOx HC

5605 150 123,0 6000 4924 5000 3592 100 4000 3000 50 2000 HC (ppm) NOx (ppm) 4,6 0,7 1000 0 0 UNIBUS HCCI, -50 HCCI, port UNIBUS HCCI, -50 HCCI, port Port inj. HCCI, individual images Port inj. HCCI, signal and surface

HCCI, (port injection) 50 RoHR Formaldehyde HCCI, (port injection) 1 OH 50 40 RoHR Formaldehyde 1 OH 0.8 40 30 0.8 0.6 30 20 0.6 RoHR (J/CAD) RoHR 0.4 20

0.4 RoHR (J/CAD) 10 0.2 10

OH- and Formaldehyde signal (a.u.) 0.2 OH- and Formaldehyde surface (a.u.) 0 0 -20 0 20 40 60 80 0 0 CAD -20 0 20 40 60 80 CAD Signal Surface fraction Direct inj. HCCI, individual images Direct inj. HCCI, signal and surface

HCCI, (SOI=-50) 50 RoHR Formaldehyde HCCI, (SOI=-50) 1 OH 50 40 RoHR Formaldehyde 1 OH 0.8 40 30 0.8 0.6 30 20 0.6 RoHR (J/CAD) 0.4 20

0.4 (J/CAD) RoHR 10 0.2 10

OH- and Formaldehyde signal (a.u.) 0.2

0 0 OH-Formaldehyde and surface(a.u.) -20 0 20 40 60 80 0 0 CAD -20 0 20 40 60 80 CAD Signal Surface fraction UNIBUS, individual images UNIBUS, signal and surface

UNIBUS, (SOI=-50 and -3) 50 RoHR Formaldehyde UNIBUS, (SOI=-50 and -3) 1 OH 50 40 RoHR Formaldehyde 1 OH 0.8 40 30 0.8 0.6 30 20 0.6 0.4 RoHR (J/CAD) 20

0.4 RoHR (J/CAD) 10 0.2 10

OH- and Formaldehyde signal (a.u.) 0.2 OH- and Formaldehyde surface (a.u.) 0 0 -20 0 20 40 60 80 0 0 CAD -20 0 20 40 60 80 CAD Signal Surface fraction Summary • The classical diesel diffusion controlled combustion will be complemented with premixed or partially premixed combustion, PPC, in the near future • PPC will enable low enough NOx without aftertreatment • PM is still an issue • PPC is very sensitive to in-cylinder mixing • Laser diagnostics can be used to give new insights to the combustion processes in diesel engines SAE HCCI symposium in Lund

• September 19-20, 2005 • Invited speakers from US, Japan and Europe • More info at www.sae.org Thank You! Acknowledgements

• The work presented has been sponsored by STEM and Vinnova through the Centre of competence combustion processes, KCFP, CeCOST, Green Car (GIHR) and by Swedish and foreign engine companies • The collaboration with the laser diagnostics group of combustion physics is greatly appreciated.