Rakesh Leeladhar Shawn GrannellRakesh Leeladhar Shawn Grannell

Stanislav Bohac Dennis AssanisStanislav Bohac Dennis Assanis

Mechanical Engineering Dept.Mechanical Engineering Dept.University Of MichiganUniversity Of Michigan

COMPARISON OFCOMPARISON OFAMMONIA / GASOLINE ANDAMMONIA / GASOLINE AND

AMMONIA / ETHANOL MIXTURESAMMONIA / ETHANOL MIXTURES

Background and MotivationBackground and Motivation

We wish to use ammonia as a primary transportation We wish to use ammonia as a primary transportation fuel.fuel.Ammonia works well at high engine loads but a Ammonia works well at high engine loads but a combustion promoter is needed at lower loads.combustion promoter is needed at lower loads.Gasoline has previously been shown to be a good Gasoline has previously been shown to be a good combustion promoter.combustion promoter.What about ethanol? Ethanol can be grown locally, can What about ethanol? Ethanol can be grown locally, can be carbon neutral, etcbe carbon neutral, etc……It would be very difficult or impossible to produce enough It would be very difficult or impossible to produce enough ethanol to displace all of the gasoline that we use. But ethanol to displace all of the gasoline that we use. But we could produce enough to use it as a combustion we could produce enough to use it as a combustion promoter.promoter.But is ethanol a good ammonia combustion promoter?But is ethanol a good ammonia combustion promoter?

OverviewOverview

Experimental EngineExperimental EngineComparison of Ethanol and Gasoline Comparison of Ethanol and Gasoline CharacteristicsCharacteristicsEthanol/Ammonia Fuel MixEthanol/Ammonia Fuel MixComparison of Gasoline/Ammonia and Comparison of Gasoline/Ammonia and Ethanol/Ammonia Fuel Mix MapsEthanol/Ammonia Fuel Mix MapsComparison of Rough and Knock LimitsComparison of Rough and Knock LimitsComparison of Thermal Efficiency Comparison of Thermal Efficiency ConclusionsConclusions

Comparison of Ethanol Gasoline PropertiesComparison of Ethanol Gasoline Properties

PropertiesProperties GasolineGasoline E85E85

RONRON 92 92 101101

Density (g/cmDensity (g/cm33)) 0.740.74 0.790.79Heat of combustion (MJ/kg)Heat of combustion (MJ/kg) 42.442.4 32.632.6Latent heat of vaporization (KJ/kg)Latent heat of vaporization (KJ/kg) 420420 845845Stoichiometric Air Fuel RatioStoichiometric Air Fuel Ratio 14.314.3 9.09.0

Characteristics of EthanolCharacteristics of Ethanol

Ethanol has a high antiknock quality due to Ethanol has a high antiknock quality due to its high octane number.its high octane number.Ethanol has a high latent heat of Ethanol has a high latent heat of vaporization.vaporization.

Advantage: Decreases the compressed gas Advantage: Decreases the compressed gas temperature during the compression stroke.temperature during the compression stroke.Disadvantage: Property influencing cold start Disadvantage: Property influencing cold start ability.ability.

Experimental InvestigationsExperimental InvestigationsRoughness LimitRoughness Limit

There are various methods to determine the cycle to There are various methods to determine the cycle to cycle variability which determines the vehicle drivability.cycle variability which determines the vehicle drivability.Pressure related parameters, burn rate related Pressure related parameters, burn rate related parameters, flame front position parameters.parameters, flame front position parameters.Pressure related quantities are the easiest and the Pressure related quantities are the easiest and the efficient way to determine the cycle to cycle variability.efficient way to determine the cycle to cycle variability.The IMEPn derived from the pressure data is expressed The IMEPn derived from the pressure data is expressed as Rough Limit= COV(IMEPas Rough Limit= COV(IMEPnn) =) = σσimepimep/IMEP/IMEPnn××100100

Knock LimitKnock LimitThe maximum gasoline fraction used to avoid knockThe maximum gasoline fraction used to avoid knock

EfficiencyEfficiencyIt is the ratio maximum work output to input.It is the ratio maximum work output to input.

Cooperative Fuel Research Engine (CFR)Cooperative Fuel Research Engine (CFR)83.4 mm bore diameter, 114.3 mm stroke, 625 cc swept volume dis83.4 mm bore diameter, 114.3 mm stroke, 625 cc swept volume displacementplacement

Effect of Compression Ratio & Load on Effect of Compression Ratio & Load on Combustion Promoter Input at Roughness LimitCombustion Promoter Input at Roughness Limit

Rough Limit Map(Gasoline)

020406080

100

0 500 1000 1500 2000Total Specific Fuel Input (J/l)

LHV

Gas

oine

In

put(%

)

8:1 COV~3%

10:1 COV~3%

12:1 COV~3%

Rough Limit Map(E85)

020406080

100

0 500 1000 1500 2000

Total Specific Fuel Input (J/l)LH

V ba

sis

E85

Inpu

t (%

)

8:1 COV~3%

10:1 COV~3%

12:1 COV~3%

14:1 COV~4%

The fraction of required promoter input decreases drastically asThe fraction of required promoter input decreases drastically as load is load is increased.increased.

The required promoter input (%) is the same for both gasoline anThe required promoter input (%) is the same for both gasoline and d ethanol mixtures at the roughness limit.ethanol mixtures at the roughness limit.

Promoter Density at Spark at Rough LimitPromoter Density at Spark at Rough Limit

00.5

11.5

22.5

33.5

44.5

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5Compressed NH3 Density @ Spark (kJ/l)

Com

pres

sed

Prom

oter

Den

sity

@ S

park

(kJ/

l)

8:1, Gasoline/NH3

10:1, Gasoline/NH3

8:1, E85/NH3

10:1, E85/NH3

Promoter Density at Spark at Rough LimitPromoter Density at Spark at Rough Limit

Gasoline

0.00.51.01.52.02.53.03.54.04.5

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

Com

pres

sed

Gas

olin

e D

ensi

ty @

Sp

ark

(kJ/

l)

8:1, COV ~3%

10:1, COV ~3%

12:1, COV ~3%

The promoter input (%) decreases as The promoter input (%) decreases as compressed NHcompressed NH33 density at spark increases.density at spark increases.

E85

0.00.51.01.52.02.53.03.54.04.5

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

Com

pres

sed

E85

Den

sity

@ S

park

(k

J/l)

8:1, COV ~3%10:1, COV ~3%12:1, COV ~3%14:1, COV ~4%

Promoter Density at Spark at Rough LimitPromoter Density at Spark at Rough Limit

8:1 and 10:1, Gasoline/NH3

y = -0.113x + 1.363

0

0.5

1

1.5

2

2.5

0 1 2 3 4 5 6 7 8

NH3 Density @ Spark (kJ/l)

Gas

olin

e D

ensi

ty @

S p

ark

(kJ/

l)

1000 RP M

1300 RP M

1600 RP M

8:1 and 10:1, E85/NH3

y = -0.2258x + 1.5712

0

0.5

1

1.5

2

2.5

0 1 2 3 4 5 6 7 8

NH3 Density @ Spark (kJ/l)Pr

omot

er D

ensi

ty @

S p

ark

(kJ/

l)

1000 RP M

1300 RP M

1600 RP M

Minimum gasoline requirement at spark= 1.36Minimum gasoline requirement at spark= 1.36

Minimum E85 requirement at spark=1.57Minimum E85 requirement at spark=1.57

Both the fuels require almost the same energy/volume at the sparBoth the fuels require almost the same energy/volume at the spark!!k!!

Promoter Density at Spark at Rough LimitPromoter Density at Spark at Rough Limit

8:1 and 10:1, Gasoline/NH3 and E85/NH3

y = -0.1512x + 1.4252

0

0.5

1

1.5

2

2.5

0 1 2 3 4 5 6 7 8NH3 Density @ Spark (kJ/l)

Prom

oter

Den

sity

@ S

park

(kJ/

l)

1000 RPM

1300 RPM

1600 RPM

Is Ammonia a Good Fuel ?Is Ammonia a Good Fuel ?

0

100

200

300

400

500

600

700

800

0 1000 2000 3000 4000

Total Specific Fuel Input (J/l)

Spec

ific

Prom

oter

Inpu

t (J/

l)

E85/NH3 8:1 1000 RPM

E85/NH3 8:1 1300 RPM

E85/NH3 8:1 1600 RPM

Gas/NH3 8:1 1000 RPM

Gas/NH3 8:1 1300 RPM

Gas/NH3 8:1 1600 RPM

The required promoter input decreases slightly as load is The required promoter input decreases slightly as load is increased., showing that ammonia as a fuel having a slighter increased., showing that ammonia as a fuel having a slighter positive or neutral effect when used with both gasoline and ethapositive or neutral effect when used with both gasoline and ethanol nol at the rough limit.at the rough limit.

Promoter Input, 10:1, All SpeedsPromoter Input, 10:1, All Speeds

0

100200

300

400

500600

700

0 500 1000 1500 2000 2500 3000 3500

Total Specific Fuel Input (J/l)

Spec

ific

Prom

oter

Inpu

t (J/

l)

E85/NH3 10:1 1000 RPME85/NH3 10:1 1300 RPME85/NH3 10:1 1600 RPMGas/NH3 10:1 1000 RPMGas/NH3 10:1 1300 RPMGas/NH3 10:1 1600 RPM

How Does Promoter Input Vary with Speed?How Does Promoter Input Vary with Speed?

400

500

600

700

800

900 1000 1100 1200 1300 1400 1500 1600 1700

Speed

Spe

cific

Pro

mot

er In

put @

NH3

cut

-in p

oint

(J

/L)

8:1 E8510:1 E8512:1 E8514:1 E858:1 gas10:1 gas12:1 gas

Knock LimitKnock Limit

0102030405060708090

100

0 500 1000 1500 2000 2500Total Specific Fuel Input (Joules /Liter)

Kno

ck L

imit

LHV

Bas

is (%

Pro

mot

er)

8:1 E85/NH35

10:1 E85/NH3

12:1 E85/NH3

14:1 E85/NH3

8:1 Gasoline/NH3

10:1 Gasoline/NH3

12:1 Gasoline/NH3

14:1 Gasoline/NH3

Knock and Rough Limit Crossover Knock and Rough Limit Crossover ––GasolineGasoline

%Gasoline decreases as total fuel input increases.%Gasoline decreases as total fuel input increases.

At some point there is a crossover between roughness At some point there is a crossover between roughness limited minimum gasoline fraction and knock limited limited minimum gasoline fraction and knock limited maximum gasoline fraction. The crossover occurs at 12:1 maximum gasoline fraction. The crossover occurs at 12:1 Compression Ratio.Compression Ratio.

0

10

20

30

40

50

60

70

80

90

100

0 500 1000 1500 2000 2500 3000 3500 4000

Total Specific Fuel Input (Joules/Liter)

LHV

Bas

is (%

Gas

olin

e)

8:110:112:114:116:1

Knock and Rough Limit Crossover Knock and Rough Limit Crossover –– E85E85

0102030405060708090

100

0 500 1000 1500 2000 2500 3000 3500 4000Total Specific Fuel Input (J/l)

LHV

basi

s %

E85

Rough Limit E85

8:1 Knock LimitE8510:1 KnockLim it E8512:1 KnockLimit E8514:1 KnockLimit E85

The Crossover occurs at 13.5:1 Compression Ratio.

Thermal Efficiency At Rough LimitThermal Efficiency At Rough Limit

E85

05

10152025303540

0 100 200 300 400 500 600 700

IMEPnN

et In

dica

ted

Ther

mal

%,A

ll s p

eeds

8:1

10:1

12:1

Gasoline

05

10152025303540

0 200 400 600 800

IMEPn

Net

Indi

cate

d

Ther

mal

%,A

ll sp

eeds

8:1

10:1

12:1

Summary of Ethanol/NH3 CombustionSummary of Ethanol/NH3 Combustionput into figureput into figure……Fuel Mix Sweep at Fuel Mix Sweep at

1600 RPM, 10:1 1600 RPM, 10:1 and IMEPand IMEPnn ~ 550 kPa.~ 550 kPa.

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120

Spark Advance(deg)

Ignition Delay(deg)

BurnDuration(degrees)

Net IndicatedThermal%

COV(IMEPn)%

ConclusionsConclusionsThe knock and rough limit crossover occurs at The knock and rough limit crossover occurs at ~13.5:1 for E85 and ~12:1 for gasoline.~13.5:1 for E85 and ~12:1 for gasoline.E85/NH3 has higher knock limit and allows for a E85/NH3 has higher knock limit and allows for a higher maximum compression ratio and thermal higher maximum compression ratio and thermal efficiency.efficiency.Gasoline/NH3 has a lower roughness limit and allows Gasoline/NH3 has a lower roughness limit and allows for a slightly more fuel mixture flexibility.for a slightly more fuel mixture flexibility.The roughness limited promoter fraction is found to The roughness limited promoter fraction is found to be almost the same for both (Ethanol &Gasoline) be almost the same for both (Ethanol &Gasoline) when used with Ammonia as the primary fuel.when used with Ammonia as the primary fuel.The fuel blend does not change much with speed.The fuel blend does not change much with speed.E85 is an attractive combustion promoter, like E85 is an attractive combustion promoter, like gasoline, when used with ammonia as the primary gasoline, when used with ammonia as the primary fuel. fuel.

Acknowledgement

Dennis Assanis , Chair, Dept. of Mechanical Engineering, University of Michigan

Stani Bohac, Research Scientist, Dept. of Mechanical Engineering, University of Michigan

Shawn Grannell, Doctoral Student, University of Michigan