Operation on Ammonia and Hydrogen at theOperation on Ammonia and Hydrogen at theRough LimitRough Limit

Shawn Grannell, Casey Stack and Donald GillespieShawn Grannell, Casey Stack and Donald Gillespie

NH3Car

OutlineOutline Combustion EquationCombustion Equation Engine and Operating ParametersEngine and Operating Parameters Predictions Based on Open Flame ExperimentsPredictions Based on Open Flame Experiments HH22/NH/NH33 Rough Limit Rough Limit Thermal Efficiency Max and Rough Limit MinThermal Efficiency Max and Rough Limit Min ConclusionsConclusions

(0.79 N(0.79 N22 + 0.21 O + 0.21 O22) + 0.42b H) + 0.42b H22 + 0.28(1-b) NH + 0.28(1-b) NH33 ⇒⇒(0.93 (0.93 –– 0.14b) N 0.14b) N22 + 0.42 H + 0.42 H22O.O.

Hydrogen is the combustion promoter.Hydrogen is the combustion promoter. b = Chemical Equivalence basis hydrogen fraction.b = Chemical Equivalence basis hydrogen fraction.

0 0 ≤≤ b b ≤≤ 1. Also fraction of hydrogen not as ammonia. 1. Also fraction of hydrogen not as ammonia.Approximates case of side stream cracking.Approximates case of side stream cracking.

Exact for case of auxiliary high pressure hydrogen tankExact for case of auxiliary high pressure hydrogen tankinstead of cracker.instead of cracker.

Combustion EquationCombustion Equation

Experimental Engine and EquipmentExperimental Engine and Equipment

CFR EngineCFR Engine Variable compression ratio 8:1 to 16:1.Variable compression ratio 8:1 to 16:1. Operation up to normally aspirated, WOTOperation up to normally aspirated, WOT Restricted speed to 1600 RPM.Restricted speed to 1600 RPM. Cylinder pressure monitored with sensorCylinder pressure monitored with sensor Single cylinder = 0.625 litersSingle cylinder = 0.625 liters

Ammonia/Propane Open FlameAmmonia/Propane Open Flame Open Flame ExperimentsOpen Flame Experiments -> One Condition, One Fuel Mix -> One Condition, One Fuel Mix

Propane Only Ammonia and Propane Inadequate Propane

Minimum HC energy fraction = 40-50% at P = 1 atm,Minimum HC energy fraction = 40-50% at P = 1 atm,TToo = room temperature = room temperature

Gasoline Input at Rough Limit for Engine ~ 600 J/LGasoline Input at Rough Limit for Engine ~ 600 J/L Cooked a turkey with Ammonia and PropaneCooked a turkey with Ammonia and Propane

Ammonia/Hydrogen Open FlameAmmonia/Hydrogen Open Flame Make a Prediction about HMake a Prediction about H22 Rough Limit Behavior Rough Limit Behavior

28% H2/72% NH3 by volume. 18% H2/82% NH3 by volume.

Minimum Hydrogen Fraction as Hydrogen ~ 20%Minimum Hydrogen Fraction as Hydrogen ~ 20%at P = 1 atm, Tat P = 1 atm, Too = room temperature = room temperature

Estimated Rough Limit Rescaling Factor ~ 1/2Estimated Rough Limit Rescaling Factor ~ 1/2 Estimated Rough Limit Hydrogen Input ~ 300 J/LEstimated Rough Limit Hydrogen Input ~ 300 J/L

0

200

400

600

800

1000

0 600 1200 1800 2400 3000

Total Spec. Fuel Input J/L

Sp

ec

. G

as

oli

ne

In

pu

t J

/L

100% Gasoline

8:1

10:1

12:1

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)

Ap

pare

nt

Mass F

racti

on

Bu

rned

Cycle 1

Cycle 2

Cycle 3

Cycle 4

Cycle 5

Rough Limit at 1600 RPM for GasolineRough Limit at 1600 RPM for Gasoline

Increasingcombustionpromoterinput percycle

IncreasingLoad

RoughLimitBehavior

Idle

NormallyAspiratedWOT

100% Gasoline Rough Limitoccurs near Idle

Could use Gasoline at Idle forall loads > Idle

0

200

400

600

800

1000

0 600 1200 1800 2400 3000

Total Spec. Fuel Input J/L

Sp

ec

. H

yd

rog

en

In

pu

t J

/L 100% Hydrogen

8:1

10:1

12:1

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)

Ap

pare

nt

Mass F

racti

on

Bu

rned

Cycle 1

Cycle 2

Cycle 3

Cycle 4

Cycle 5

Rough Limit at 1600 RPM for HydrogenRough Limit at 1600 RPM for Hydrogen

Increasingcombustionpromoterinput percycle

IncreasingLoad

RoughLimitBehavior

Idle

NormallyAspiratedWOT

7% H2 forRough Lim.7-10% forconstant H2

100% H2 Rough Limit occurssubstantially below Idle

Could use Rough Limit at Idlefor all loads > Idle

0

200

400

600

800

1000

0 600 1200 1800 2400 3000

Total Spec. Fuel Input J/L

Sp

ec

. H

yd

rog

en

In

pu

t J

/L 100% Hydrogen

8:1

10:1

12:1

Rough Limit at 1600 RPM, 12:1 forRough Limit at 1600 RPM, 12:1 forHydrogenHydrogen

IncreasingLoad

Idle

AirAmmonia

Hydrogen

Rough Limit = 3% COV(IMEPRough Limit = 3% COV(IMEPnn))Rough Limit For HydrogenRough Limit For Hydrogen

0

1

2

3

4

5

6

7

8

100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250

Specific Hydrogen Input Near (J/L)

CO

V(I

ME

Pn

) (%

)

8:1

10:1

12:1

14:1

16:1

0

1

2

3

4

5

100 120 140 160 180 200 220 240 260 280 300

Specific Hydrogen Input (J/L)

CO

V(I

ME

Pn

) (%

)

8:1

10:1

12:1

14:1

16:1

Near Idle WOTNear Idle WOT

WOT RoughLimit

12:1 RoughLimit near Idle

Rough Limit and Efficiency Trends ~ IdleRough Limit and Efficiency Trends ~ Idle

100

150

200

250

300

8 9 10 11 12 13 14 15 16

Compression Ratio

Sp

ec

. H

2 I

np

ut

Ne

ar

Idle

(J

/L)

34

34.5

35

35.5

36

36.5

8 9 10 11 12 13 14 15 16

Compression Ratio

Gro

ss In

d T

herm

al E

ff. %

Rough Limit PromoterInput Minimum andEfficiency MaximumOccur at SameCompression Ratio!

Rough Limit HydrogenInput ~ 200 J/L

For Gasoline, this was~600 J/L

Rough Limit RescalingFactor = 1/3

The ammonia fueled engine works.The ammonia fueled engine works. It can be made to work with gasoline for partialIt can be made to work with gasoline for partial

operation on ammonia, or hydrogen foroperation on ammonia, or hydrogen forammonia-only operation.ammonia-only operation.

100 Billion gallons of gasoline/year equivalent100 Billion gallons of gasoline/year equivalentfor U.S. = 374 Gigawatts = 694 million tonsfor U.S. = 374 Gigawatts = 694 million tonsNHNH33/year./year.

ConclusionsConclusions There is a compression ratio at which the combustionThere is a compression ratio at which the combustion

promoter requirement is minimized, and in this case itpromoter requirement is minimized, and in this case itis the same compression ratio for which efficiency isis the same compression ratio for which efficiency ismaximized, in this case about 12:1.maximized, in this case about 12:1.

The required ammonia decomposition fraction is notThe required ammonia decomposition fraction is notconstant. The hydrogen input/cycle ~ constant.constant. The hydrogen input/cycle ~ constant.

The specific promoter input at the rough limit near idleThe specific promoter input at the rough limit near idleis about 200 J/L for hydrogen, whereas for gasoline itis about 200 J/L for hydrogen, whereas for gasoline itwas about 600 J/L. The hydrogen partial energy inputwas about 600 J/L. The hydrogen partial energy inputat the rough limit is about 1/3 of that of gasoline.at the rough limit is about 1/3 of that of gasoline.

The required % decomposition of ammonia at WOTThe required % decomposition of ammonia at WOTshould be about 7-10%.should be about 7-10%.