“refuel” - ffrc · 2010-01-25 · • refuel strategy: – use of nexbtl – advanced miller...

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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!

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