Influence of Fuel Ethanol Content on PN and PM …Influence of Fuel Ethanol Content on PN and PM from Direct Injection Gasoline Engines Dr. Piotr Bielaczyc, Joseph Woodburn, Dr. Andrzej

Influence of Fuel Ethanol Content on PN and PM from Direct Injection Gasoline Engines

Dr. Piotr Bielaczyc, Joseph Woodburn, Dr. Andrzej Szczotka

BOSMAL Automotive Research and Development Institute Ltd

Concern over particulate matter emissions from automotive engines has been expressed for decades [1]. This has lead to the introduction of both mass and number-based emissions limits for Diesel vehicles in the European Union; direct-injection petrol engines have now also had a particle number limit set, and it is likely that all automotive internal combustion engines will be subject to particle mass and number limits in the future. These limits have necessitated (or will necessitate) the implementation of measures aimed at reducing particle emissions, through changes to the calibration, fuel injectors, etc; and by implementing filtration devices (Diesel particulate filters, Gasoline particulate filters). The direct injection concept exhibits better fuel consumption and this engine type will eventually come to dominate park-ignited automotive engines. Ambitious targets for the implementation of biofuels in the European Union are slowly changing the composition of both petrol and Diesel fuels used in the EU, with impacts on particle emissions. Thus, investigations into the effect of ethanol blends on direct injection engines are of great importance for the future. A series of experiments was performed to determine the impact of fuel ethanol content and ambient temperature on particle number and mass emissions from a European gasoline vehicle featuring a direct injection engine. Testing was performed according to the EU legislative test procedure, over the New European Driving Cycle, using a chassis dynamometer, foil-backed TX40 filters for quantification of particle mass and a PMP-compliant particle counting system for quantification of particle number emissions. Tests were performed using ethanol blends E5 (i.e. 5% ethanol by volume), E10, E25 and E50 at both temperatures currently specified for SI vehicles in EU legislation: +24 °C and -7 °C. Figures 1a and 1b present particle mean number and mass emissions results obtained for the various petrol-ethanol blends.

0.0

2.5

5.0

7.5

10.0

E5 E10 E25 E50

PM

em

issi

on

[mg

/km

]

Fuel blend

PM, 24 deg C

PM, -7 deg C

Nodata

1E+10

1E+11

1E+12

1E+13

E5 E10 E25 E50

PN

em

issi

on

[#/k

m]

Fuel blend

PN, 24 deg C

PN, -7 deg C

Nodata

Figure 1 – a) particle mass (PM) emissions obtained over the NEDC at +24 °C and -7 °C for various ethanol blends

Figure 1 –b) particle number (PN) emissions obtained over the NEDC at +24 °C and -7 °C for various ethanol blends

Usage of an oxygenated fuel is generally thought to improve the combustion process and reduce particulate emissions. However, despite the increased oxygen content of the fuel, higher ethanol blends showed decreases in particle number and mass emissions which ranged from small to non-existent. The E10 and E50 blends performed well at the lower test temperature regarding their mass emissions, but showed no real advantage in terms of number emissions. Regarding comparison to the legislative limits, which are mandated for a 20-30 °C ambient temperature, the mass limit was fulfilled for all fuel blends; the phase-in particle number

limit was just met for all blends, but the long-term limit of 6.00E11 #/km was exceeded for every fuel blend.

In line with previous examinations (e.g. [2,3]), the semi-log space created by co-plotting particle mass emissions (linear scale) and particle number emissions (log10 scale) was employed. While the two metrics are not directly comparable, as they measure somewhat different aspects, graphical and numerical explorations of the relationship between particle mass and number can be informative for a variety of reasons, both theoretical and practical [1]. Figure 2 presents particle number emissions plotted as a function of particle mass emissions, alongside the future legislative limits.

y = 9E+11x + 4E+11R² = 0.9204

1.00E+11

1.00E+12

1.00E+13

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0

PN

em

issi

on

[mg

/km

]

PM emission [mg/km]

SIDI limit SIDI limit - phase-in Data Trend (ethanol blends)

Figure 2 – a semi-log plot of particle number and mass results from one direct injection vehicle tested over the NEDC, with ethanol blends E5 to E50. Raw results (from both phases of the cycle) are presented in comparison to

the EU legislative limits

The trendline’s y intercept value was found to of a similar order of magnitude to the gradient, and thus the trendline was not forced through the origin. The observed PN/PM gradient is reasonably close to previously reported correlations for Diesel vehicles (with DPFs) [e.g. 2], but the large y-intercept value implies the presence of large numbers of particles of almost zero mass, in contrast to correlations observed for Diesel engines (with a DPF). Possible reasons include the physicochemical parameters of the two fuels – and the impact this has on the relative sizes of the volatile and non-volatile particle fractions, the presence or absence of a particulate filter, injection pressure, combustion temperature, etc. Fuel ethanol content was observed to correlate only weakly with PN/PM ratio (Figure 3), as previously reported in another study [3]. Further testing would be necessary to definitely determine the existence of a correlation between fuel ethanol content and this metric. In order to determine the nature of the response of PM and PN emissions to the ethanol content of the fuel blend, it would be necessary to conduct further testing with a greater number of ethanol blends of low and moderate ethanol content. Additionally, in order to further understand the effect of ambient temperature, tests could be conducted at temperatures between the two mandated EU test temperatures.

1.00E+11

1.00E+12

1.00E+13

0 10 20 30 40 50

PN

/PM

ra

tio

[#/m

g]

Blend ethanol content [Vol. %]

UDC EUDC

Figure 3 – The ratio of PN to PM results obtained at 24°C for various ethanol blends

Considering the concurrent trends of increasing interest in direct injection petrol engines and increasing concern over particle number and surface area, research in this area remains an intriguing necessity. Since usage of both ethanol and direct injection engines will increase in the future, the subject addressed in this research is of considerable interest regarding future emissions scenarios. Likewise, further investigations into the relative merits of each particulate matter metric (mass, number, size distribution, effective surface area) and their reliability and relevance to real world emissions are paramount.

References:

[1] Kittlelson, D.B. Engines and nanoparticles: a review. Journal of Aerosol Science, 29, 5-6, 575-588, 1998. DOI: 10.1016/S0021-8502(97)10037-4.

[2] Bielaczyc, P., et al. Correlation between particle mass and number for Euro 5 compression ignition vehicles, Book of Abstracts, The 15th ETH-Conference on Combustion Generated Nanoparticles, Zurich, Switzerland, 26-29 June 2011.

[3] Maricq, M.M., et al. The Impact of Ethanol Fuel Blends on PM Emissions from a Light-Duty GDI Vehicle, Aerosol Science and Technology, 46, 5, 2012. DOI: 10.1080/02786826.2011.648780.

16th ETH Conference on Combustion Generated Nanoparticles24th – 27th June 2012, Zurich, Switzerland

Investigations on fuel ethanol content and bi t t t ti l b ambient temperature on particle number

and mass emissions from vehicles featuring direct injection gasoline engines

Piotr Bielaczyc, Andrzej Szczotka, Joseph WoodburnBOSMAL Automotive R&D Institute Ltd, Poland

P. Bielaczyc 25th June 2012 16th ETH-Conference 1

,

Presentation contentsPresentation contents

Research context & Experimental aims

Introduction

Experimental Details

Results & Discussion

Conclusions


Research context & Experimental aimsResearch context & Experimental aims The physicochemical characteristics of standard petrol and ethanol

differ widely. The addition of even small quanitities of ethanol to

petrol has been shown to affect gaseous exhaust emissions. Other

studies have reported effects on PM and PN emissions.

This study seeks to obtain further information on PM (mass) and

PN (number) emissions with fuels of varying ethanol content.

Interest in direct injection engines is increasing and this engine type Interest in direct injection engines is increasing and this engine type

will be used much more widely in the future. Interest is using

greater quantities of ethanol in gasoline is also increasing The greater quantities of ethanol in gasoline is also increasing. The

research presented here is therefore of great importance for future

t ti i i


automotive emissions.

Introduction:

Concern over particulate matter emissions from

Introduction:

Concern over particulate matter emissions from automotive engines has been expressed for decades

This has lead to the introduction of both mass and number-based emissions limits for Diesel vehicles in the European Union; direct-injection petrol engines have now also had a particle number limit set: 6.00x1012

#/km (for the year 2014); 6 00x1011 #/km for the year#/km (for the year 2014); 6.00x1011 #/km for the year2017

Interest is gowing in using increased quantities of ethanol in petrol fuel blends for automotive applications


p pp

Background: ethanol as an automotive fuel:

Using ethanol as a vehicular fuel is not a new ideag

Primary alcohol, formula C2H5OH Suitable for use in SI engines, usually blendedg y

h l0% ethanol 100 % gasoline

100% ethanol0% gasoline

E85E5 E10 …etc…


Background: petrol-ethanol blends worldwide

Sweden: E85E85

EU:

USA: E E

E5…E10 India: E5, E10

Brazil: E18-25,

E10, E15Australia:

E105,E85, E100


Background: ethanol as an automotive fuel:

Interest has been growing in ethanol Interest has been growing in ethanol

Potentially sustainable, renewable biofuel, depending on feedstock

The EU’s Fuel Quality Directive (2009/30/EC) enabled more

widespread use of ethanol in petrol in the EU (blends up to E10)

Currently the most widely-used biofuel

All ‘standard’ gasoline sold in the EU is currently E5g y 5

US EPA approved E15 for use in recent model year cars


Direct Injection Spark Ignition (DISI) engineect ject o Spa g t o ( S ) e g e

The major advantages of a j gDISI engine are increased fuel efficiency and high power outputp p

Emissions levels can also be more accurately be more accurately controlled with the DISI system

No throttling losses in some DISI engines, when compared to a compared to a conventional fuel-injected engine


Direct Injection Gasoline engineDirect Injection Gasoline engine Engine speed is controlled by the

engine control unit/engine engine control unit/engine management system (EMS), which regulates fuel injection function and ignition timing

High fuel efficiency is an advantage; emissions of particulate matter are a disadvantagedisadvantage

The literature suggests that DISI PM emissions are higher than SI MPI PM emissions are higher than SI MPI PM emissions and DISI PN emissions are much much higher than SI MPI PN emissions

DISI engines will come to have the largest market share for SI engines in the future


the future

0,20Vehicle type A - CI - IDI

Background: Example emissions

0,16

ypVehicle type B - CI - IDIVehicle type C - CI - IDIVehicle type D - CI - DIVehicle type E - CI - DI

C

D0,12

n [

g/k

m]

ypVehicle type F - SI - DIVehicle type G - SI - MPIVehicle type H - SI - MPI

A

AA

B

B

B

CC

C

DDD

EE

F

0,08

M e

mis

sio

n

AA

BB

C DD

EE

E

FF

0,04

PM

FF

F

GGGGGHHHHH

0,00

195 s 195 s 390 s 400 s UDC+EUDC195 s 195 s 390 s 400 s UDC+EUDC

PM emissions for different vehicles with SI and CI engineSource: Bielaczyc P., Szczotka A., Pajdowski P. EAEC Conference 2001


Pajdowski P. EAEC Conference 2001

Background: Filter overviewCI - IDI SI - DI

SI - MPICI - DI

Filters with particulate matters from NEDC cycle for different types of vehicles

CI - IDI SI - DI SI - MPI SI - CNG

Filters with particulate matters from first 195 s of NEDC cycle for different types of vehiclesSource: Bielaczyc P., Szczotka A., P jd ki P EAEC C f


Pajdowski P. EAEC Conference 2001

Experimental Details


Experimental Details : test facility Schematic diagram of BOSMAL’s emissions measurement setup, as used to

measure emissions from the test vehicles

Experimental Details : test facility


Experimental Details : test facility BOSMAL’s climate-controlled test chamber

(-35 °C to +60 °C) housing a chassisdynamometer and windspeed fan Emissions analysers

Dilution tunnel and particle countery p

Testing carried out in accordance with EU & PMP test requirements.

Test temperatures: +24 °C and -7 °C Driving cycle: NEDC

Three tests performed on each fuel (meanvalues plotted in graphs)

Blends E5, E10 and E50 tested at -7 °C (twot t bl d l l tt d h )


Driving cycle: NEDC tests blend; mean values plotted on graphs)

Experimental Details: VehicleExperimental Details: VehicleVehicle type Passenger car

E i i S d d E Emission Standard Euro 5Engine capacity [dm3] Approx. 1.4

Max. Power [kw] 67Max. Torque [Nm] 200

Aftertreatment system Close Coupled TWC

λ λ = 1

(stoichiometric)


Results & Discussion


Results: PM & PN during the NEDCResults: PM & PN during the NEDC

NEDC

1,00E+13PN

3

3,5PM

2

2,5

3

1,00E+12

1

1,5

2

PN

1,00E+11

E 5 E 10 E 25 E 50 E 5 EOT

0

0,5PM

/k /kE 5 E 10 E 25 E 50 E 5 EOT

• Limited effect for PN (considering test-to-test variability); stronger effect for PM

#/km mg/km


• Mass and number emissions lowest from the E50 blend and highest from the E10 blend

Results: PM & PN during the UDCResults: PM & PN during the UDC

UDCPN PM

1,00E+13

PN

5

6

PM

1 00E+12 3

4

1,00E 12

1

2

3

PN

1,00E+11

E 5 E 10 E 25 E 50 E 5 EOT

0

1PM

/k5 0 5 50 5 O

• Limited effect for PN (considering test-to-test variability); stronger effect for PM

#/km mg/km


• Mass and number emissions lowest from the E50 blend and highest from the E10 blend

Results: PM & PN during the EUDCResults: PM & PN during the EUDCEUDCPN PM

1,00E+13

1,61,82

1,00E+12

11,21,4,

1,00E+11

0 20,40,60,8

PN

1,00E+10

E 5 E 10 E 25 E 50 E 5 EOT

00,2PM

#/km mg/km

• Wide variation between blends for PM; relatively little for PN (considering test-to-test variability)• Mass and number emissions highest from the E10 blend• Low emissions from the E50 blend despite a substantially increased fuel flow rate

#/km mg/km


• Low emissions from the E50 blend, despite a substantially increased fuel flow rate

Results: PN/PM ratios for the UDC and EUDC3,00E+12

UDC EUDC

2,50E+12

mg]

1 50E 12

2,00E+12

M ra

tio [#

/

1,00E+12

1,50E+12

PN/PM

5,00E+11

,

0 10 20 30 40 50Blend ethanol content [Vol. %]

• No obvious correlation observed between ethanol content and the PN/PM ratio• Very low repeatability


• Very low repeatability

Results: PM & PN during the NEDC at 7 CResults: PM & PN during the NEDC at -7 CNEDC

1,00E+13PN

12,00PM

8,00

10,00

1,00E+12

4,00

6,00

PN

1,00E+11 0,00

2,00PM

E 5 E 10 E 50

• Wide variation between blends for PM; very low emissions for the E50 blend

mg/km#/km


y

Results: PM & PN during the UDC at 7 CResults: PM & PN during the UDC at -7 C

UDC

1 00E 13PN

25 00PM

1,00E+13

20,00

25,00

1,00E+1210 00

15,00

5,00

10,00PN

PM

1,00E+11

E 5 E 10 E 50

0,00

mg/km#/km


Results: PM & PN during the EUDC at 7 CResults: PM & PN during the EUDC at -7 C

EUDC

1 00E 13PN

25 00PM

1,00E+13

20,00

25,00

1,00E+1210 00

15,00

5,00

10,00UDC PN

UDC PM

1,00E+11

E 5 E 10 E 50

0,00

mg/km#/km


Results: Temperature influence for E51401.00E+12

E5 (24 d C)

1201.00E+11

E5 (24 deg C)

E5 (-7 deg C)

Vehicle speed

100

1.00E+10

/h]

#/cm

3 ]

60

80

1.00E+09

icle

sp

eed

[km

on

cen

trat

ion

[#

40

1.00E+08

Veh

Par

ticl

e c o

201.00E+07

01.00E+060 200 400 600 800 1000 1200

Time [s]

• Significantly higher emission at -7 °C for idling and transientsDiff ll b di f d 650 d


• Differences all but disappear after around 650 seconds

1401.00E+13E10 (24 deg C)

Results: Temperature influence for E10

1201.00E+12

E10 (24 deg C)

E10 (-7 deg C)

Vehicle speed

1001.00E+11

m/h

]

[#/c

m3 ]

60

80

1.00E+09

1.00E+10

hic

le s

pee

d [

km

con

cen

trat

ion

[

401.00E+08

Veh

Par

ticl

e c

201.00E+07

01.00E+060 200 400 600 800 1000 1200

Time [s]

• Significantly higher emission at -7 °C for idling and transientsDiff ll b di f d 650 d


• Differences all but disappear after around 650 seconds

1401.00E+12E50 (24 deg C)

Results: Temperature influence for E50

1201.00E+11

E50 (24 deg C)

E50 (-7 deg C)

Vehicle speed

100

1.00E+10

m/h

]

[#/c

m3 ]

60

80

1.00E+09

hic

le s

pee

d [

km

con

cen

trat

ion

[

40

1.00E+08

Veh

Par

ticl

e c

201.00E+07

01.00E+060 200 400 600 800 1000 1200

Time [s]

• Significantly higher emission at -7 °C for idling and transients up to around 400 seconds• Surprisingly emission at -7 °C in fact lower for some portions of the cycle (550-900 seconds)


• Surprisingly, emission at -7 C in fact lower for some portions of the cycle (550-900 seconds)

Conclusions


Conclusions (1/2)Conclusions (1/2)

At 24 C PN emissions were high but were (just) under At 24 C, PN emissions were high, but were (just) underthe upcoming limit of 6.00E12 #/km for all test fuels.PM emissions were all well under the DISI limit.

Emissions of PN and PM increased substantially at -7 C,but the difference varied with the ethanol content of thefuel.

Possible reasons include the physicochemicalt f th t f l d th i t thi hparameters of the two fuels – and the impact this has on

the relative sizes of the volatile and non-volatile particlefractions catalyst light-off time and the oxidation offractions, catalyst light off time and the oxidation ofparticles in the TWC.


Conclusions (2/2)Conclusions (2/2)

While considerable variation was observed, fuelethanol content was observed to correlate onlyethanol content was observed to correlate onlyweakly with the PN/PM ratio. The results suggestthat large numbers of particles of negligible massthat large numbers of particles of negligible masswere emitted.

Despite the increased oxygen content of the fuel, Despite the increased oxygen content of the fuel,higher ethanol blends showed limited to non-existent decreases in particle number and masse ste t dec eases pa t c e u be a d assemissions, although the E50 blend did appear toperform well.


p

Thank you for your attention

Any questions?

Thank you for your attention

Any questions?

Contact: [email protected]


Documents

Influence of Fuel Ethanol Content on PN and PM …Influence of Fuel Ethanol Content on PN and PM from Direct Injection Gasoline Engines Dr. Piotr Bielaczyc, Joseph Woodburn, Dr. Andrzej