Polttomoottoritekniikka/Aki Tilli 14.1.2010 Tulevaisuuden dieselpalamistekniikat synteettisille ja uusiutuville polttoaineille “ReFuel”
Polttomoottoritekniikka/Aki Tilli
14.1.2010
Tulevaisuuden
dieselpalamistekniikat synteettisille
ja uusiutuville polttoaineille
“ReFuel”
Collaboration - International
• Part of a Collaborative Task of the IEA
Combustion Agreement
• “Refuel” is also a collaboration framework
between IEA Combustion Agreement and
IEA AMF (Advance Motor Fuels)
Agreement
Collaboration - Domestic
TKK
ÅA
TUT
VTT
Neste Renewable Fuels
Sisu Agco Power
Wärtsilä
Aker Arctic
TEKES
Goals
• Combustion optimization: utilize the
potential of renewable high cetane number
paraffinic fuels and their oxygenate blends
• Emissions: CO2, NOX, PM reduction
– Meeting future emission standards without or
with minimum after-treatment
• Simultaneous high efficiency and high
specific power output
Fuels
• Reference: typical EN590
requirements fulfilling
diesel fuel
• NExBTL, a representative
of very high cetane number
paraffinic fuel
• NExBTL+oxygenate blends Trad. diesel and synthetic diesel
(ASFE 2006)
Emission reduction techniques• EGR: exhaust gas recirculation
• Miller cycle
Implementation• Literature review (TKK, VTT)
• Reaction scheme evaluations (ÅA)
• Emission mapping calculations (ÅA, TKK)
• Optimum combustion design with CFD (TKK)
• Fuel spray studies (TKK)
• Engine tests (TKK) – high-speed research engine, LEO
– medium-speed research engine, EVE
• Extensive emission measurements (VTT)
• Particulate emission analysis (TTY)
Literature study• Previous studies on high CN fuels: as such and
with parameter optimization
• Oxygenate candidate studyOxygen Flash point Distillation Density Cetane
wt-% °C °C kg/dm3
number
Reference fuels
Diesel fuel*** 0 >56 170-340°C ~0.84 >51
Ethanol*** 34.8 13 78 0.794 8
FAME*** 10 >100 300-340 0.88 >50
Oxygenate candidates
n-Pentyl ether, DNPE C10H22O10*** 57*** 187*** 0.783*** 111-130***
2-Ethoxyethyl ether (Diethyl diglycol, Diethyl carbitol) C8H18O330*** 71*** 189*** 0.91*** 113-136***
Diethylene glycol dimethyl ether (Diglyme) 35.8 67 162** 0.945 112**
Triethylene glycol dimethyl ether (Triglyme) C8H18O435.9 111 220** 0.986 144**
Tripropylene glycol methyl ether (TPGME) CH3(OC3H6)3OH31* 242* 0.96* 65*
Glycerol-t-butyl ether (GTBE) 0.88* 35.2*
Cyclohexanone C6H10O16.3* 155* 0.95* 10*
Dibutylmaleate (DBM) C12H20O426* >110 281* 0.99* 28*
Diethoxy butane 22 45*** 97***
Dibutoxy methane (Butylal) 20 62 180*** 0.8354 >74***
2-Methoxyethyl acetate 40.7 145 1.01
Sources: Natarajan et al. 2001 *) Boot et al. 2007, 2009 **) Kozak et al. 2007 ***) Nylund et al. 2005
Literature study• EGR: many previous high CN fuel studies
– With parameter changes and without aftertreatment, max. ~70% PM and NOx reductions have been achieved, separately
• Miller cycle: no studies found with high CN fuels
Literature study: NExBTL benefits• Physical properties => wide spray, small SMD, quick
evaporation => short liquid spray penetration, good mixing => PM reduction
• High CN => extreme Miller and higher EGR rate possible => NOx reduction potential
– however, short premixing phase may lead to higher PM
• No aromatics, paraffinic => clean, complete combustion (=> less PM) at lower temperatures => NOx -reduction
• Pilot injection => more stable combustion
• Injection timing control? Early injection: more NOx, less PM
• Low effective compression ratio (Miller): lower T => NOx reduced
• Oxygenates => even more complete combustion, especially in rich zones => PM reduction. Combustion T lower => less NOx.
Reaction scheme evaluations:
Phi-T maps
Example of calculated soot and NO maps• to study influence of exhaust gas composition, temperature, in-
cylinder conditions and fuel composition
•C1-C2 mechanism (incl.
linear hydrocarbon formation
up to C6)
•N-heptane mechanism
•Toluene mechanism
•PAH mechanism
•Polyyne mechanism (CxH2)
•Soot mechanism
(particulate phase, non-
elementary reactions)
•NO mechanism
CFD and Phi-T Maps • Fuel injection, combustion, and emission simulations in a
single-cylinder heavy-duty size
research engine
• Using Phi-T maps and CFD
to analyze current
combustion system
• Locate areas where the
strongest emission
formation is taking place
• The target is to optimize the
combustion system to avoid
strongly sooting and NOx producing
areas in the Phi-T mapTemperature iso-surface (2500K) in a diesel
engine sector model during combustion
10 crank angle degrees after the start of fuel
injection. Ossi Kaario
CFD and Phi-T Maps
CFD fuel spray studies
Experimental fuel spray studies• Measurements are
carried out to figure
out fundamental spray
properties and to support the computational studies.
• The spray penetration, opening angle and droplet
diameter of different nozzles and fuels are measured with
laser based backlight imaging.
• Studies are made using a pressurized test chamber
imitating real engine conditions at the end of the
compression stroke.
Backlight Image of fuel spray
1,6 mm / 0,02 ms
11,1 mm / 0,07 ms
15,6 mm / 0,12 ms
17,1 mm / 0,17 ms
19,0 mm / 0,22 ms
21,0 mm / 0,27 ms
24,5 mm / 0,37 ms
27,8 mm / 0,47 ms
29,9 mm / 0,57 ms
38,1 mm / 0,97 ms
Fuel Spray Studies• So far,
– experimental arrangements
are completed
– preliminary test sets are
performed and analysed
• In the near future,
– high speed engine
measurements will be
completed and analysed in
February 2010.
Figure. The pressurized test chamber for fuel spray
studies.
Engines: LEO
• High-speed
single-cylinder
research diesel
engine
• Based on
SisuDiesel 84
CTA
Engines: LEODone:
• electrohydraulic valve mechanism installed
• reference runs
• reference emission levels– regulated emissions
– particle size measurements (VTT)
– unregulated emissions (VTT)
Engines: LEO
What next..?
• during 2010 EGR-
and Miller runs
• at the end of 2010:
optimized process
runs
• 2011 oxygenate runs0
0.8
1.6
2.4
3.2
4
4.8
5.6
6.4
7.2
8
8.8
9.6
10.4
11.2
12
12.8
-360 -180 0 180 360
Pako
Imu
Imu_Miller_1
Imu_Miller_2
Engines: EVE
• Medium-speed
single-cylinder
research diesel
engine
• Based on
Wärtsilä engines
(W20 injector)
0
2.5
5
7.5
10
12.5
15
17.5
120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640
CAD
va
lve
lift
(mm
)
EVE Miller REF intake
EVE Miller REFexhaust
A-reference intake
A-reference exhaust
B intake
C intake
D intake
Engines: EVE
• ReFuel strategy:
– Use of NexBTL
– Advanced Miller cycle
– Exhaust Gas Quantity
• Project phases
1. Reference Runs with Diesel (STD valve timing)
2. Reference Runs with NExBTL (STD valve timing)
3. Runs with Advanced Miller cycle, with Early IVC
4. Runs with Advanced Miller Cycle and Negative
Scavenging
Thank you!