3-1 boehman, andre presentations... · 2019. 8. 21. · 11/14/2016 3 experimental methodology for...

11/14/2016

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Ignition Behavior of Gasolines and Surrogate Fuels under LTC and

Dilute ConditionsVickey Kalaskar

Department of Energy & Mineral EngineeringPenn State University

Dongil KangDepartment of Chemical Engineering

University of Michigan

Kwang Hee Yoo and André L. Boehman*Department of Mechanical Engineering

University of Michigan

*Professor of Mechanical EngineeringDirector, Walter E. Lay Automotive Laboratory

Associate Director, Automotive Research Center

Kalghatgi (PROCI 2015 and other papers)

• In HCCI engines the global ϕ <1 and fuel and air are fully premixed so that soot formation can be avoided

• There is no in-cycle control of combustion phasing in HCCI engines

• A fuel in the gasoline autoignition range (RON>60) can be used instead of a diesel fuel in a CI engine

• The higher ignition delay of such fuels allows more time for mixing of the fuel and oxygen before combustion starts GCI

• GCI engines offer at least diesel-like efficiency at lower cost compared to running diesel engines on conventional diesel fuels and could use fuels that are “less processed” compared to current gasoline and diesel

What should GCI fuels look like?

• Lack of fuel quality metrics – RON, OI, etc. may not adequately describe ignition behavior of the optimal fuel (Goldsborough et al., DOE AMR 2016) – ANL RCM measuring fundamental autoignition

data at relevant conditions– Understand effects of fuel composition on LTC

trends (e.g.,τID, LTHR)– Similar motivation in the work in our group with a

combination of our motored CFR Octane Rating engine and optically instrumented cetane rating instrument (CID 510)

What should GCI fuels look like?

Goldsborough et al., DOE AMR 2016

Relevance of Surrogates

Example: DOE – Volvo SuperTruck program

Davis, DOE AMR 2010

Target 55% Thermal Efficiency

• Volvo: Aero and Engine Efficiency

Volvo SuperTruck 1

Gibble, DOE AMR 2016

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Volvo SuperTruck 1

Gibble, DOE AMR 2016

Vickey Kalaskar doctoral thesis gasoline surrogate autoignition to

match a PPC gasoline

New Collaboration with Aramco Services

Validation of Surrogate Fuels Representing some FACE Gasolines

• Support the development of fuels and engines for GCI applications,

• Work with model fuels and surrogate fuels explore the sensitivities of these combustion processes to specific fuel properties

• Compare the combustion behavior of a set of FACE gasolines and surrogate mixtures that have been proposed to represent those FACE gasolines (specifically FACE A, C, I and J) (e.g., Sarathy and co-workers, PROCI 2016, and other studies)

Autoignition characteristic of neo‐pentane at of 0.25

CO emission

In-cylinder gas Tmax

3 4 5 6 7 8 9 10 11

0

20

40

Compression Ratio

CO

(F

uel

Car

bon

%)

(II)(I) (III) (IV) (V)

HTONTCLTO

600

800

1000

1200

In

-Cyl

ind

er G

as T

max

(K

)

LTHR firstly appeared

-60 -40 -20 0 20 40 60

0

1

2

3

4

5

Ap

pa

ren

t H

ea

t R

ele

as

e R

ate

(J

/de

g)

Crank Angle (deg)

CR5.8

-60 -40 -20 0 20 40 60

0

1

2

3

4

5

Ap

pa

ren

t H

ea

t R

ele

as

e R

ate

(J

/de

g)

Crank Angle (deg)

CR7

-60 -40 -20 0 20 40 60

0

1

2

3

4

5

Ap

pa

ren

t H

ea

t R

ele

as

e R

ate

(J

/de

g)

Crank Angle (deg)

CR9.5

2nd stage HR firstly appeared

-60 -40 -20 0 20 40 60

0

1

2

3

4

5

Ap

pa

ren

t H

ea

t R

ele

as

e R

ate

(J

/de

g)

Crank Angle (deg)

CR10.1CCR (HTHR)

(I) No CO formation due to low in‐cylinder temperature (<700K)

(II) Onset of CO formation where evident LTHR first appears

(III) Level CO concentration over a wide range of CR due to the NTC behavior (800‐900K)

(IV) Rapid growth of CO formation in hot ignition (thermal‐runaway) temperature range (900‐1100K), where evident two stage heat release is first observed

(V) A sudden drop of net CO formation mostly due to conversion to CO2 (>1200K), defined as the critical compression ratio (CCR) and HTHR

-60 -40 -20 0 20 40 60

0

1

2

3

4

5

Ap

pa

ren

t H

ea

t R

ele

as

e R

ate

(J

/de

g)

Crank Angle (deg)

CR4

No LTHR

Classification of Global Oxidation

10

Modified CFR Engine – Fuel Autoignition

1

• Modified octane rating engine

• Intake air controlled for temperature to ensure mixture homogeneity

• Fuel flow controlled using a GDI injector

• Variable compression ratio (4 – 15)

• Intake pressure (atmospheric to 3 bar, abs)

• Provisions for condensing the exhaust for reaction pathway analysis

PPC Fuels Matrix

• Base fuels are iso-Octane (RON 100) and PRF 80 (RON 80)• Blends are determined to match the RON of base fuels• Fuels investigated are binary and ternary blends of n-

Heptane, iso-Octane and a fuel of interest (Toluene, Ethanol, or iso-Butanol)

1

FUEL n-Heptane iso-Octane Toluene Ethanol iso-Butanol

Density [g/cm3] 0.6795 0.692 0.8719 0.789 0.802

RON, ASTM D2699 [-] 0 100 118 109 113

MON, ASTM D2700 [-] 0 100 103.5 90 94

Lower Heating Value (LHV) [MJ/kg]

44.55 44.34 40.52 26.82 33.1

Reid vapor pressure, ASTM D5191 [psi]

1.6 1.7 1.3 16.0 3.3

Toluene fuel matrixIso-Butanol fuel matrixEthanol fuel matrixExpressed as a volume fraction Predicted values

S(RON-MON)

Measured RON

ASTM (D2699)n-Heptane iso-Octane Toluene RON MON

T1 0.28 0.52 0.20 80 79.10 0.895 77.7

T2 0.35 0.30 0.35 80 74.73 5.263 76.7

T3 0.41 0.09 0.50 80 70.36 9.638 74.4

T4 0.06 0.74 0.20 100 96.50 3.496 98.1

T5 0.10 0.55 0.35 100 93.91 6.089 97.1

T6 0.15 0.35 0.50 100 91.34 8.656 97.0

* Model from Ghosh et al. used to predict RON and MON

Expressed as a volume fraction Predicted valuesS(RON-MON)

n-Heptane Iso-Octane Ethanol RON MON

E1 0.35 0.45 0.20 77.44 69.81 7.63

E2 0.45 0.2 0.35 76.48 65.38 11.10

E3 0.50 0.00 0.50 78.08 64.47 13.61

E4 0.10 0.70 0.20 96.32 88.58 7.80

E5 0.2 0.45 0.35 92.88 81.58 11.30

E6 0.25 0.25 0.50 92.91 79.09 13.81

* Linear blending rule by Anderson et al. used to predict RON and MON

Expressed as a volume fraction Predicted valuesS(RON-MON)

n-Heptane Iso-Octane iso-Butanol RON MON

I1 0.30 0.50 0.20 77.62 71.93 5.68

I2 0.35 0.30 0.35 77.88 68.86 9.01

I3 0.40 0.10 0.50 77.64 65.86 11.77

I4 0.05 0.75 0.20 99.66 93.82 5.83

I5 0.15 0.50 0.35 94.36 85.17 9.18

I6 0.15 0.35 0.50 97.21 85.19 12.02

RON 80

RON 100

Fuels matrix selected to study the interaction between reactive n‐ and iso‐paraffins, and less reactive, high octane components

PPC Fuels Matrix

• Ethanol blends have higher vol % of n-Heptane compared to Toluene and iso-Butanol blends

• RON estimation for Ethanol blends resulted in some error

• Predicted values used to discuss the results

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EXPERIMENTAL METHODOLOGY FOR CFRENGINE STUDIES

13

• Engine speed constant at 600 RPM

• Intake temperature and Φ maintained constant ( 155 °C, 0.25), intake pressure swept in steps up to 3 bar

• At each intake pressure, CR is gradually increased (from 4) until significant HTHR (auto-ignition) is observed

• CO emission is used as indicator for HTHR and autoignition

• For few blends, exhaust condensed in DCM for GC analysis

IntroductionMotivationLiteraturereviewHypothesesExperimentalsetup(study3)

SIGNIFICANT DIFFERENCES OBSERVED FOR PRFS

14

IntroductionMotivationLiteraturereviewHypothesesResults(Study3)

• Base fuel RON 100: iso-Octane (ITN), Base fuel RON 80: PRF 80 are shown

• CCR for PRF 80 much lower than iso-octane

• Also, CO emission during low temperature regime is higher for PRF 80 blend suggesting higher reactivity

PRF 100

PRF 80

COMPARISON OF AHRRPROFILES FOR PRFS REVEAL SIGNIFICANT DIFFERENCESIN LOW TEMPERATURE REACTIVITY

• PRF 80 exhibited significantly higher low temperature reactivity compared to iso-Octane

• PRF 80 ignited at much earlier CRs compared to iso-Octane

• Iso-Octane exhibited two-stage behavior at higher intake pressure indicating improved reactivity

15


CR 7.4

CR 8.43

CR 9.8

CR 11.6

CR 14.1

CR 5.9

CR 6.5

CR 7.3

CR 8.35

CR 10.7

MAXIMUM BULK TEMPERATURES AND PRESSURES FOR ISO‐OCTANE AND PRF80INDICATE DIFFERENCES IN LOW TEMPERATURE REACTIVITY

• The HTHR occurs at similar “thermal runaway” temperatures at a given intake pressure― Suggesting that the onset of HTHR governed by iso-Octane

• HTHR initiated at lower maximum bulk temperature at higher intake pressure

16


1 BAR3 BAR

CCRTRENDS FOR BLENDS DIFFER FROM BASE PRFFUELS SUGGESTINGDIFFERENCES IN REACTION PATHWAYS

• RON 100 blends, toluene blends fairly match with iso-Octane

• Significant differences observed for alcohol blends compared to iso-Octane

17


Toluene blends Ethanol blends iso-Butanol blends

RON 100

Differences in Toluene and Alcohol CCR trends suggest distinctly different reaction mechanism

CCRTRENDS FOR BLENDS DIFFER FROM BASE PRFFUELS SUGGESTINGDIFFERENCES IN REACTION PATHWAYS

• RON 80 blends exhibited similar CCRs compared to PRF 80

• For RON 80 blends, CCR delay attributed to increasing % of less reactive, fuels of interest

18


Toluene blends Ethanol blends iso-Butanol blends

RON 80

The delay in CCR happens despite the presence of higher n-Heptane content for blends with higher % of fuel of interest

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• At higher intake pressure, Toluene blends and iso-Octane exhibited LTHR

• However HTHR is delayed for blends containing higher % of Toluene

• As a result Toluene blends ignite later compared to iso-octane

• Iso-Octane does not show any heat release at CR 13 while iso-Butanol blends with higher % of iso-Butanol and n-Heptane show significant heat release at CR 12.7

• As a result, iso-Octane ignited much later compared to iso-Butanol blends

• Similar results observed for Toluene and Ethanol blends

• Toluene blends show two-stage heat release similar to iso-Octane at higher intake pressure

• Ethanol suppresses the two-stage heat release at the highest intake pressure1 BAR3 BAR

AHRRPROFILES INDICATE DISTINCT DIFFERENCES IN TOLUENE AND ALCOHOLBLENDS COMPARED TO THE PRFFUELS

19


iso-Butanol blends

CR 13.0

CR 12.7

CR 12.8

CR 13.25

CR 12.75

CR 14.1

RON 100

Toluene blends

CR 7.0 CR 7.2

Toluene blends Ethanol blends

CR 7.4

CR 7.38

CR 7.6

CR 7.73

CR 7.4

CR 8.05

CR 7.8

CR 7.9

AHRRPROFILES INDICATE DISTINCT DIFFERENCES IN TOLUENE AND ALCOHOLBLENDS COMPARED TO THE PRFFUELS

20


1 BAR

RON 80• Toluene blends showed similar LTHR compared to PRF 80 and ignited earlier

• Ethanol in the blends suppressed the LTHR and hence the blends ignited later compared to PRF 80

Ethanol blends

CR 10.7

CR 10.58

CR 10.3

CR 10.55

CR 10.7

CR 11.0

CR 11.0

CR 11.2

• At higher intake pressure iso-Butanol delays the LTHR resulting in delayed CCRs

• Similar behavior exhibited by Toluene and Ethanol blends 3 BAR

iso-Butanol blends

CR 5.8

CR 5.8

CR 5.98

CR 6.1

CR 6.25CR 5.8

CR 6.13

CR 6.1

CR 6.18

CR 5.8

CR 5.88

CR 5.85

CR 6.0

Toluene blends

Conclusions for PPC Fuels study

• Reactivity of iso-Octane increased with increasing intake pressure more in comparison with the blend matrix under study

• Blends under study exhibit different CCR trends as a function of increasing intake pressure indicating different reaction pathways which were based on fuel composition

• Two distinct mechanisms are observed as compared with the PRF blends

– Alcohol in the blends is associated with consuming the radical pool generated by the more reactive components (n-Heptane and iso-Octane) in the blends thus inhibiting/delaying LTHR

– Toluene did not affect the LTHR significantly but the stable resonant cyclic structure delays the onset of HTHR at most of the test conditions indicated by higher “thermal runaway” temperatures

2 Aramco Services Company 22

Aramco GCI and FACE fuels

Property RON 60 RON 70 RON 80 FACE A FACE C FACE I FACE J

H/C 2.136 2.044 1.967 2.271 2.172 2.246 1.901

Distillation(°C)

IBP 26.8 38.2 36.6 33.9 35.1 37.8 38.3

EP 138.4 170 188 131.7 164.5 126.1 181.1

RVP (psi) 6.38 6.5 7.2 8.1 7.4 7.5 7.5

Composition(vol %)

Aromatics 6.8 13.7 19.7 0 2.1 0.9 27.8

Olefins <0.3 3 5.6 0.4 0.4 6.2 1

Saturates 93 83.4 74.7 99.6 97.5 92.9 71.2

RON 61 70 80 83.5 84.7 70.3 71.8

DCN (CID 510) 32.7 27.8 23.3 26.2 25.6 29.9 26.5

Aramco Services Study: Fuel Properties

CRC report (2014)

Aramco Services Company 23

CFR engine test conditions

Condition Value

Engine speed (rpm) 600

Intake temperature (°C) 190

Intake pressure (bar) 1, 2, 3*

Fuel injection temperature (°C) 90

Cooling jacket temperature (°C) 90

Equivalence ratio 0.25, 0.50

* Under the high intake pressure conditions, the partial pressures of the gasolines at the selected equivalence ratios are lower than their saturated vapor pressure. This ensured that the injected fuel was fully vaporized as it entered the engine.

Aramco Services Study: Test Conditions Critical Compression Ratio


3 4 5 6 7 8 9 10 11 12 13600

700

800

900

1000

1100

1200

1300

1400

1500

FACE A FACE C FACE I FACE J

Max

In-

cylin

der

Tem

per

atu

re (

K)

Compression Ratio

3 4 5 6 7 8 9 10 11 12 13600

700

800

900

1000

1100

1200

1300

1400

1500

RON 60 RON 70 RON 80

Max

In-

cylin

der

Tem

per

atu

re (

K)

Compression Ratio

3 4 5 6 7 8 9 10 11 12 13

0

2000

4000

6000

8000

10000

12000

14000

16000


CO

Em

issi

ons

(pp

m)

Compression Ratio

3 4 5 6 7 8 9 10 11 12 13

0

2000

4000

6000

8000

10000

12000

14000

16000


CO

Em

issi

ons

(p

pm)

Compression Ratio

at equivalence ratio of 0.25

Overall ignition reactivity:RON 60 > FACE J (RON 71.8) > RON 70 > FACE I (RON 70.3) > RON 80 > FACE C (RON 84.7) > FACE A (RON 83.5)

11/14/2016

5

3 4 5 6 7 8 9 10600

700

800

900

1000

1100

1200

1300

1400

1500


Max

In-

cylin

der

Tem

per

atu

re (

K)

Compression Ratio

3 4 5 6 7 8 9 10600

700

800

900

1000

1100

1200

1300

1400

1500


Max

In-

cylin

der

Tem

per

atu

re (

K)

Compression Ratio

3 4 5 6 7 8 9 10

0

1000

2000

3000

4000

5000

6000

7000


CO

Em

issi

ons

(pp

m)

Compression Ratio

3 4 5 6 7 8 9 10

0

1000

2000

3000

4000

5000

6000

7000


CO

Em

issi

ons

(pp

m)

Compression Ratio

Critical Compression Ratio



Overall ignition reactivity:RON 60 > RON 70 > FACE J (RON 71.8) > FACE I (RON 70.3) > RON 80 > FACE C (RON 84.7) > FACE A (RON 83.5)

-60 -40 -20 0 20 40 60-2

0

2

4

6

8

10

12

14


AH

RR

(J/

deg

)

Crank Angle (deg)

-60 -40 -20 0 20 40 60-2

0

2

4

6

8

10

12

14


AH

RR

(J/

deg)

Crank Angle (deg)

% Low Temperature Heat Release


% Low temperature heat release

Equivalenceratio

RON 60 RON 70 RON 80 FACE A FACE C FACE I FACE J

0.25 9.07 0 0 0 0 0 0

0.50 10.89 0 0 0 0 0 0

at CCR

Φ = 0.25 Φ = 0.25

Intake Pressure Effect


0.5 1.0 1.5 2.0 2.5 3.0 3.53

5

7

9

11

13

Crit

ical

Co

mpr

ess

ion

Ra

tio

Intake Pressure (bar)

FACE A, 0.25 FACE C, 0.25 FACE I, 0.25 FACE J, 0.25 FACE A, 0.50 FACE C, 0.50 FACE I, 0.50 FACE J, 0.50

0.5 1.0 1.5 2.0 2.5 3.0 3.53

5

7

9

11

13

Crit

ical

Co

mpr

ess

ion

Ra

tio

Intake Pressure (bar)

RON 60, 0.25 RON 70, 0.25 RON 80, 0.25 RON 60, 0.50 RON 70, 0.50 RON 80, 0.50

3 4 5 6 7 8 9 10 11

0

2000

4000

6000

8000

10000

12000

14000

16000

3 bar 2 bar

atmospheric

FACE I FACE J

C

O E

mis

sio

ns (

ppm

)

Compression Ratio

3 4 5 6 7 8 9

0

1000

2000

3000

4000

5000

6000

7000

FACE I FACE J

CO

Em

issi

ons

(pp

m)

Compression Ratio

2 bar

atmospheric

Φ = 0.25

Φ = 0.5

Effect of Intake Pressure on CCR


Vickey Kalaskar (2015)

0.5 1.0 1.5 2.0 2.5 3.0 3.53

5

7

9

11

13

Crit

ical

Co

mpr

ess

ion

Ra

tioIntake Pressure (bar)

FACE A, 0.25 FACE C, 0.25 FACE I, 0.25 FACE J, 0.25 FACE A, 0.50 FACE C, 0.50 FACE I, 0.50 FACE J, 0.50

-60 -40 -20 0 20 40 60-2

0

2

4

6

8

10

1 bar, CR 11.7 2 bar, CR 7.45 3 bar, CR 5.6

AH

RR

(J/

deg)

Crank Angle (deg)


-60 -40 -20 0 20 40 60-2

0

2

4

6

8

10

1 bar, CR 11.4 2 bar, CR 7.3 3 bar, CR 5.5

AH

RR

(J/

deg)

Crank Angle (deg)

% Low temperature heat release

Intakepressure

RON 60 RON 70 RON 80 FACE A FACE C FACE I FACE J

1 bar 9.07 0 0 0 0 0 0

2 bar 24.78 15.17 1.10 2.77 9.29 7.25 10.83

3 bar 38.51 22.19 11.58 17.23 21.71 28.98 20.67

(1) RON 80 (2) FACE A


Intake Pressure Effect Conclusions from GCI Fuels Study – So Far

• Reactivity of even high octane fuels is substantially enhanced at high boost levels

– Two stage ignition and significant LTHR observed under boosted conditions for fuels with no LTHR at naturally aspirated conditions

– Need to identify correlation with fuel composition– Kinetic mechanisms need to capture these effects

during simulation• Continuing work will include FACE fuel surrogate

studies

• Ongoing work includes ignition delay measurements in our CID510 instrument, spray ignition with separation of τphys and τchem

3

3-1 boehman, andre presentations... · 2019. 8. 21. · 11/14/2016 3 experimental methodology for...

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