THE OPERATING FEATURES OF A THE OPERATING FEATURES OF A STOICHIOMETRIC, AMMONIA AND STOICHIOMETRIC, AMMONIA AND GASOLINE DUAL FUELED SPARK GASOLINE DUAL FUELED SPARK

IGNITION ENGINEIGNITION ENGINEByBy

Shawn Grannell Dennis AssanisShawn Grannell Dennis AssanisStanislav Bohac Don GillespieStanislav Bohac Don Gillespie

University of MichiganMechanical Engineering Dept. & Applied Physics Program

Supported by the Fannie and John Hertz Foundation.

OverviewOverview

Experimental EngineExperimental EngineBasic FeaturesBasic FeaturesFuel Mix MapFuel Mix MapRough and Knock LimitsRough and Knock LimitsThermal EfficiencyThermal EfficiencyEngine Out EmissionsEngine Out EmissionsPost Catalyst EmissionsPost Catalyst EmissionsConclusionsConclusions

(0.79 N(0.79 N22 + 0.21 O+ 0.21 O22) + 0.024b C) + 0.024b C66HH1111 + 0.28(1+ 0.28(1--b) NHb) NH33⇒⇒ (0.93 (0.93 –– 0.14b) N0.14b) N22 + (0.42 + (0.42 –– 0.288b) H0.288b) H22O + O + 0.144b CO0.144b CO22

Lower Heating Value (LHV) energy yield: (88.7 Lower Heating Value (LHV) energy yield: (88.7 –– 4b) kJ4b) kJb = fraction of the oxygen burned by gasoline. b = fraction of the oxygen burned by gasoline. 0 0 ≤≤ b b ≤≤ 11Stoichiometric ammonia/air mixture has 83% of energy Stoichiometric ammonia/air mixture has 83% of energy density of stoichiometric gasoline/air mixture.density of stoichiometric gasoline/air mixture.Gasoline is the combustion promoter. Other fuels Gasoline is the combustion promoter. Other fuels such as hydrogen could be used as combustion such as hydrogen could be used as combustion promoters.promoters.

Ideal Combustion EquationIdeal Combustion Equation

CFR Engine FeaturesCFR Engine Features

Variable compression ratio.Variable compression ratio.Supercharge Capability.Supercharge Capability.Cylinder pressure monitored with sensor.Cylinder pressure monitored with sensor.Rigorous, calibrated measurements during steady Rigorous, calibrated measurements during steady state operation.state operation.Single cylinder = 0.625 liters.Single cylinder = 0.625 liters.Ammonia used without decomposing any of it Ammonia used without decomposing any of it first.first.

Catalytic Converter

Engine Out Oxygen Sensor

Post Catalyst Oxygen Sensor

Spark Advance

Compression Ratio Crank

Gasoline Injector

Intake Chamber

Intake Air Heater

Supercharge Air Hose

Work Definitions:Work Definitions:

IMEPIMEPgg = (gross) Indicated Mean Effective Pressure. = (gross) Indicated Mean Effective Pressure. ((kPakPa) The effective piston driving pressure for ) The effective piston driving pressure for compression/expansion.compression/expansion.IMEPIMEPnn = (net) Indicated Mean Effective Pressure. = (net) Indicated Mean Effective Pressure. ((kPakPa) Same, but also includes intake/exhaust processes.) Same, but also includes intake/exhaust processes.BMEP = Brake Mean Effective Pressure. The effective BMEP = Brake Mean Effective Pressure. The effective driving pressure for work available at the crankshaft.driving pressure for work available at the crankshaft.FMEP = Friction Mean Effective Pressure. For most FMEP = Friction Mean Effective Pressure. For most engines, this is about 1engines, this is about 1--1.5 bar.1.5 bar.BMEP = IMEPBMEP = IMEPnn -- FMEP.FMEP.

What is IMEPWhat is IMEPnn??Throttled Throttled

0

500

1000

1500

2000

0 0.2 0.4 0.6 0.8

Cylinder Volume (Liters)

Cyl

inde

r Pre

ssur

e (k

Pa) Intake

CompressionExpansionExhaust

Exhaust & Intake Pumping Loop

Gross Indicated Work

Net Indicated Work

+

=

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

-30 -20 -10 0 10 20 30 40 50 60 70 80

Crank Angle (deg)

App

aren

t Mas

s Fr

actio

n B

urne

d fo

r 8:1

, 16

00 R

PM, I

MEP

n ~

550

kPa

87% Gas/13% NH3, COV = 0.7%35% Gas/65% NH3, COV = 2.8%24% Gas/76% NH3, COV = 16.6%

What happens at the rough limit?What happens at the rough limit?

What about Knock?What about Knock?

-20

-15

-10

-5

0

5

10

15

20

25

-5 0 5 10 15 20 25 30

Crank Angle (degrees)

Kno

ck S

igna

l (kP

a), G

asol

ine,

10:

1, p

eak

pres

sure

= 2

9 ba

r.

Knock Filter Output

-20

-15

-10

-5

0

5

10

15

20

25

-5 0 5 10 15 20 25 30

Crank Angle (degrees)

Kno

ck S

igna

l (kP

a), A

mm

onia

, 12

:1, p

eak

firin

g pr

essu

re =

100

bar

.

Ammonia doesn’t knock at 100 bar

Gasoline knocks at 20-30 bar

Cylinder Pressure and Mass Fraction BurnedCylinder Pressure and Mass Fraction Burned

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

-30 -20 -10 0 10 20 30 40 50 60 70 80

Crank Angle (degrees)

App

aren

t Mas

s Fr

actio

n B

urne

d

Cycle 1

Cycle 2

Cycle 3

Cycle 4

Cycle 5

1.6

1.8

2

2.2

2.4

0.2 0.4 0.6 0.8 1

Log10(Cylinder Volume)

Log 1

0(C

ylin

der P

ress

ure) Cycle 1

Cycle 2

Cycle 3

Cycle 4

Cycle 5

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

-30 -20 -10 0 10 20 30 40 50 60 70 80

Crank Angle (degrees)

App

aren

t Mas

s Fr

actio

n B

urne

d

Cycle 1

Cycle 2

Cycle 3

Cycle 4

Cycle 5

1.6

1.8

2

2.2

2.4

0.2 0.4 0.6 0.8 1

Log10(Cylinder Volume)

Log 1

0(C

ylin

der P

ress

ure)

Cycle 1

Cycle 2

Cycle 3

Cycle 4

Cycle 5

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

-30 -20 -10 0 10 20 30 40 50 60 70 80

Crank Angle (degrees)

App

aren

t Mas

s Fr

actio

n B

urne

d

Cycle 1

Cycle 2

Cycle 3

Cycle 4

Cycle 5

1.8

2

2.2

2.4

2.6

0.2 0.4 0.6 0.8 1

Log10(Cylinder Volume)

Log 1

0(C

ylin

der P

ress

ure)

Cycle 1

Cycle 2

Cycle 3

Cycle 4

Cycle 5

Rough Limit Smooth, MBT RetRough Limit Smooth, MBT Retarded Sparkarded Spark

Increasing gasoline input per cycle

Fuel Mix Sweep for 8:1, 1600 RPM, Fuel Mix Sweep for 8:1, 1600 RPM, IMEPnIMEPn = = 550 550 kPakPa

0

10

20

30

40

50

60

70

80

90

0 20 40 60 80 100LHV Basis (% Gasoline)

(Deg

rees

) or (

%) a

s sp

ecifi

edSpark Adv. (deg)Ign. delay (deg)Burn Duration (deg)Net Ind. Th. (%)COV (IMEPn) (%)

Rough limit

Knock limit

The Rough LimitThe Rough Limit

0102030405060708090

100

0 200 400 600 800 1000 1200 1400

IMEPn (kPa)

LHV

Bas

is (%

Gas

olin

e) 8:1

10:1

12:1

Throttled SuperchargedIdle

Normally aspirated road load

Ammonia Favored Here

Charge density at spark depends on load at Charge density at spark depends on load at rough limit sparkrough limit spark..

02468

1012141618

-80 -60 -40 -20 0 20 40 60 80

Crank Angle (degrees)

Inst

anta

neou

s C

ompr

essi

on R

atio 8:1

12:116:1

Rough Limit Spark Occurs Here

Rough limit behavior depends on charge Rough limit behavior depends on charge density @ sparkdensity @ spark

0

0.5

1

1.5

2

2.5

3

3.5

0 1 2 3 4 5 6 7 8Compressed NH3 Density @ Spark (kiloJoules/Liter)

Com

pres

sed

Gas

olin

e De

nsity

@ S

park

(kJ/

L)8:110:112:1

Ammonia has nearly neutral effect on flammability

At high load and low speed, rough limit is hard to find

The Knock Limit and Knock/Rough Limit The Knock Limit and Knock/Rough Limit Crossover at 12:1Crossover at 12:1

0102030405060708090

100

0 200 400 600 800 1000 1200 1400

IMEPn (kPa)

LHV

Bas

is (%

Gas

olin

e) 8:1

10:112:114:116:1R.L.

Throttled SuperchargedIdle

Charge density depends on load and Charge density depends on load and compression ratio at incipient knockcompression ratio at incipient knock..

02468

1012141618

-80 -60 -40 -20 0 20 40 60 80

Crank Angle (degrees)

Inst

anta

neou

s C

ompr

essi

on R

atio 8:1

12:116:1

Knock Occurs Here

20

22

24

26

28

30

32

34

36

38

0 200 400 600 800 1000 1200 1400

IMEPn (kPa)

Net

Indi

cate

d Th

erm

al E

ffici

ency

%

7:18:19:110:1

Power and Efficiency for GasolinePower and Efficiency for Gasoline

Throttled Supercharged

Idle

Decreasing C.R.

Increasing C.R.

Efficiency for NHEfficiency for NH33/Gasoline, Rough Limit/Gasoline, Rough Limit

20

22

24

26

28

30

32

34

36

38

0 200 400 600 800 1000 1200 1400

IMEPn (kPa)

Net I

ndic

ated

The

rmal

Effi

cien

cy (%

)

8:110:112:1

Throttled Supercharged

Idle

20

22

24

26

28

30

32

34

36

38

0 200 400 600 800 1000 1200 1400IMEPn (kPa)

Net

Indi

cate

d Th

erm

al E

ffici

ency

(%)

8:110:112:114:116:1

Efficiency for NHEfficiency for NH33/Gasoline, Knock Limit/Gasoline, Knock Limit

Throttled Supercharged

Idle

0

5

10

15

20

25

30

35

0 100 200 300 400 500 600 700 800 900 1000 1100

BMEP (kPa)

Bra

ke T

herm

al E

ffici

ency

(%),

1000

RPM

Gas/NH3, 8:1Gas/NH3, 10:1Gas/NH3, 12:1Gasoline, 7:1 to 10:1

Brake Thermal EfficiencyBrake Thermal Efficiency

Throttled Supercharged

Idle

EngineEngine--Out Out Pollutant Pollutant

EmissionsEmissions

0

3000

6000

9000

12000

15000

18000

21000

24000

0 20 40 60 80 100

Ammonia ppm wet

0

2000

4000

6000

8000

10000

0 20 40 60 80 100LHV basis (% Gasoline)

Eng

ine-

Out

Pol

luta

nt E

mis

sion

s Ammonia ppm wetNitric Oxide ppm wetCarbon Monoxide ppm wetHC dry ppm (C1)

Gasoline turned OFF

0

500

1000

1500

2000

2500

-1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

Equivalence Ratio Deviation from Stoich. (%)

Post

Cat

Pol

luta

nts

(ppm

) for

Gas

olin

e

CO ppm wet

HC ppm dry C1

NH3 ppm wet

NO ppm wet

N20 ppm x10, wet

Post Catalyst Emissions, Gasoline OnlyPost Catalyst Emissions, Gasoline Only

RichLean

0

500

1000

1500

2000

2500

-1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

Equivalence Ratio Deviation from Stoich. (%)

Post

Cat

Pol

luta

nts

(ppm

) for

1/4

Gas

olin

e, 3

/4

NH 3

CO ppm wet

HC ppm dry C1

NH3 ppm wet

NO ppm wet

N20 ppm x10, wet

Post Catalyst Emissions, Post Catalyst Emissions, ¼¼ Gas., Gas., ¾¾ NHNH33

RichLean

0

1000

2000

3000

4000

5000

6000

7000

8000

-3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5

Equivalence Ratio Deviation from Stoich. (%)

Post

Cat

Em

issi

ons,

100

% N

H3

NH3 ppm wet

NO ppm wet

N20 ppm x10, wet

Post Catalyst Emissions, Ammonia OnlyPost Catalyst Emissions, Ammonia Only

RichLean

Operating ConclusionsOperating Conclusions

The effect of compression ratio on the fuel mix at the The effect of compression ratio on the fuel mix at the rough limit was weaker than expected. rough limit was weaker than expected. An efficiency improvement is obtained for a modestly An efficiency improvement is obtained for a modestly increased compression ratio of 10:1 or perhaps 12:1. increased compression ratio of 10:1 or perhaps 12:1. Knock and diminished return on efficiency make Knock and diminished return on efficiency make compression ratios above 12:1 undesirable. compression ratios above 12:1 undesirable. The improved efficiency of the ammonia fueled engine The improved efficiency of the ammonia fueled engine is due mostly to the effective removal of the knock is due mostly to the effective removal of the knock constraint at modest compression ratios, which allows constraint at modest compression ratios, which allows the engine to operate with better mechanical efficiency the engine to operate with better mechanical efficiency and reduced pumping losses at arbitrarily high loads.and reduced pumping losses at arbitrarily high loads.

Emissions ConclusionsEmissions Conclusions

Engine out emissions of hydrocarbons and carbon Engine out emissions of hydrocarbons and carbon monoxide are replaced with ammonia when ammonia is monoxide are replaced with ammonia when ammonia is substituted for gasoline.substituted for gasoline.Lean operation must be absolutely avoided with Lean operation must be absolutely avoided with ammonia, otherwise post catalyst emissions of nitrogen ammonia, otherwise post catalyst emissions of nitrogen oxides can exceed the engine out values. oxides can exceed the engine out values. Emissions clean up with a catalyst at stoichiometric, as Emissions clean up with a catalyst at stoichiometric, as they also do for gasoline.they also do for gasoline.