COMPARISONCOMPARISON OFOF AMMONIAAMMONIA // GASOLINEGASOLINE ANDAND AMMONIAAMMONIA // ETHANOLETHANOL MIXTURESMIXTURES RakeshRakesh LeeladharLeeladhar ShawnShawn GrannellGrannell StanislavStanislav BohacBohac DennisDennis AssanisAssanis MechanicalMechanical EngineeringEngineering Dept.Dept. UniversityUniversity OfOf MichiganMichigan BackgroundBackground andand MotivationMotivation z We wish to use ammonia as a primary transportation fuel. z Ammonia works well at high engine loads but a combustion promoter is needed at lower loads. z Gasoline has previously been shown to be a good combustion promoter. z What about ethanol? Ethanol can be grown locally, can be carbon neutral, etc… z It would be very difficult or impossible to produce enough ethanol to displace all of the gasoline that we use. But we could produce enough to use it as a combustion promoter. z But is ethanol a good ammonia combustion promoter? OverviewOverview z ExperimentalExperimental EngineEngine z ComparisonComparison ofof EthanolEthanol andand GasolineGasoline CharacteristicsCharacteristics z Ethanol/AmmoniaEthanol/Ammonia FuelFuel MixMix z ComparisonComparison ofof Gasoline/AmmoniaGasoline/Ammonia andand Ethanol/AmmoniaEthanol/Ammonia FuelFuel MixMix MapsMaps z ComparisonComparison ofof RoughRough andand KnockKnock LimitsLimits z ComparisonComparison ofof ThermalThermal EfficiencyEfficiency z ConclusionsConclusions ComparisonComparison ofof EthanolEthanol GasolineGasoline PropertiesProperties PropertiesProperties GasolineGasoline E85E85 RONRON 9292 101101 DensityDensity (g/cm(g/cm3)) 0.740.74 0.790.79 HeatHeat ofof combustioncombustion (MJ/kg)(MJ/kg) 42.442.4 32.632.6 LatentLatent heatheat ofof vaporizationvaporization (KJ/kg)(KJ/kg) 420420 845845 StoichiometricStoichiometric AirAir FuelFuel RatioRatio 14.314.3 9.09.0 CharacteristicsCharacteristics ofof EthanolEthanol z EthanolEthanol hashas aa highhigh antiknockantiknock qualityquality duedue toto itsits highhigh octaneoctane number.number. z EthanolEthanol hashas aa highhigh latentlatent heatheat ofof vaporization.vaporization. z Advantage:Advantage: DecreasesDecreases thethe compressedcompressed gasgas temperaturetemperature duringduring thethe compressioncompression stroke.stroke. z Disadvantage:Disadvantage: PropertyProperty influencinginfluencing coldcold startstart ability.ability. ExperimentalExperimental InvestigationsInvestigations ¾ RoughnessRoughness LimitLimit ¾ There are various methods to determine the cycle to cycle variability which determines the vehicle drivability. ¾ Pressure related parameters, burn rate related parameters, flame front position parameters. ¾ Pressure related quantities are the easiest and the efficient way to determine the cycle to cycle variability. ¾ The IMEPn derived from the pressure data is expressed as Rough Limit= COV(IMEPn) = σimep/IMEPn×100 ¾ KnockKnock LimitLimit ¾ The maximum gasoline fraction used to avoid knock ¾ EfficiencyEfficiency ¾ It is the ratio maximum work output to input. Cooperative Fuel Research Engine (CFR) 83.4 mm bore diameter, 114.3 mm stroke, 625 cc swept volume displacement EffectEffect ofof CompressionCompression RatioRatio && LoadLoad onon CombustionCombustion PromoterPromoter InputInput atat RoughnessRoughness LimitLimit Rough Limit Map(Gasoline) Rough Limit Map(E85) 100 100 80 ) 80 % 8:1 COV~3% ( 8:1 COV~3% (% ) 60 60 10:1 COV~3% ut 10:1 COV~3% 40 p 40 12:1 COV~3% Input Input In 20 20 12:1 COV~3% 14:1 COV~4% LHV basis E85 E85 LHV basis LHV Gasoine 0 0 0 500 1000 1500 2000 0 500 1000 1500 2000 Total Specific Fuel Input (J/l) Total Specific Fuel Input (J/l) ¾The fraction of required promoter input decreases drastically as load is increased. ¾The required promoter input (%) is the same for both gasoline and ethanol mixtures at the roughness limit. PromoterPromoter DensityDensity atat SparkSpark atat RoughRough LimitLimit 4.5 8:1, Gasoline/NH3 4 10:1, Gasoline/NH3 3.5 8:1, E85/NH3 10:1, E85/NH3 3 2.5 2 1.5 1 0.5 Compressed Promoter Density @ Spark (kJ/l) 0 00.511.522.533.544.5 Compressed NH3 Density @ Spark (kJ/l) PromoterPromoter DensityDensity atat SparkSpark atat RoughRough LimitLimit Gasoline E85 4.5 4.5 8:1, COV ~3% 4.0 8:1, COV ~3% 4.0 10:1, COV ~3% 10:1, COV ~3% 3.5 12:1, COV ~3% 3.5 12:1, COV ~3% 14:1, COV ~4% 3.0 3.0 2.5 2.5 2.0 (kJ/l) 2.0 Spark (kJ/l) 1.5 1.5 1.0 1.0 0.5 0.5 Compressed E85 Density @ Spark E85 Density Compressed Compressed Gasoline Density @ 0.0 0.0 012345678 012345678 Compressed NH3 Density @ Spark (kJ/l) Compressed NH3 Density @ Spark (kJ/l) TheThe promoterpromoter inputinput (%)(%) decreasesdecreases asas compressedcompressed NHNH3 densitydensity atat sparkspark increases.increases. PromoterPromoter DensityDensity atat SparkSpark atat RoughRough LimitLimit 8:1 and 10:1, E85/NH3 8:1 and 10:1, Gasoline/NH3 2.5 2.5 1000 RPM 2 2 1000 RPM ) 1300 RPM ) 1300 RPM 1600 RPM 1.5 1600 RPM kJ/l 1.5 kJ/l ( ( 1 1 ark ark ark ark p p S y = -0.113x + 1.363 S y = -0.2258x + 1.5712 0.5 0.5 Gasoline Density @ Density Gasoline 0 @ Density Promoter 0 012345678 012345678 NH3 Density @ Spark (kJ/l) NH3 Density @ Spark (kJ/l) Minimum gasoline requirement at spark= 1.36 Minimum E85 requirement at spark=1.57 Both the fuels require almost the same energy/volume at the spark!! PromoterPromoter DensityDensity atat SparkSpark atat RoughRough LimitLimit 8:1 and 10:1, Gasoline/NH3 and E85/NH3 2.5 2 1000 RPM 1300 RPM 1.5 1600 RPM 1 0.5 y = -0.1512x + 1.4252 0 Promoter Density @ Spark (kJ/l) Spark @ Promoter Density 012345678 NH3 Density @ Spark (kJ/l) IsIs AmmoniaAmmonia aa GoodGood FuelFuel ?? 800 700 600 500 400 300 E85/NH3 8:1 1000 RPM E85/NH3 8:1 1300 RPM 200 E85/NH3 8:1 1600 RPM Specific Promoter Input (J/l) Input Promoter Specific Gas/NH3 8:1 1000 RPM 100 Gas/NH3 8:1 1300 RPM Gas/NH3 8:1 1600 RPM 0 0 1000 2000 3000 4000 Total Specific Fuel Input (J/l) ¾ The required promoter input decreases slightly as load is increased., showing that ammonia as a fuel having a slighter positive or neutral effect when used with both gasoline and ethanol at the rough limit. PromoterPromoter Input,Input, 10:1,10:1, AllAll SpeedsSpeeds 700 600 500 400 E85/NH3 10:1 1000 RPM E85/NH3 10:1 1300 RPM 300 E85/NH3 10:1 1600 RPM 200 Gas/NH3 10:1 1000 RPM Gas/NH3 10:1 1300 RPM 100 Gas/NH3 10:1 1600 RPM Specific Promoter Input (J/l) Input Promoter Specific 0 0 500 1000 1500 2000 2500 3000 3500 Total Specific Fuel Input (J/l) HowHow DoesDoes PromoterPromoter InputInput VaryVary withwith Speed?Speed? 800 700 600 (J/L) 8:1 E85 10:1 E85 500 12:1 E85 14:1 E85 8:1 gas 10:1 gas 12:1 gas Specific Promoter Input @ NH3 cut-in point point cut-in @ Input NH3 Promoter Specific 400 900 1000 1100 1200 1300 1400 1500 1600 1700 Speed KnockKnock LimitLimit 100 90 80 8:1 E85/NH35 70 10:1 E85/NH3 60 12:1 E85/NH3 50 14:1 E85/NH3 40 8:1 Gasoline/NH3 30 10:1 Gasoline/NH3 20 12:1 Gasoline/NH3 10 14:1 Gasoline/NH3 0 Knock Limit LHV Basis (% Promoter) Promoter) (% Basis LHV Limit Knock 0 500 1000 1500 2000 2500 Total Specific Fuel Input (Joules/Liter) KnockKnock andand RoughRough LimitLimit CrossoverCrossover –– GasolineGasoline 100 8:1 90 10:1 80 12:1 e) 70 14:1 16:1 60 50 40 30 LHV Basis (% Gasolin (% Basis LHV 20 10 0 0 500 1000 1500 2000 2500 3000 3500 4000 Total Specific Fuel Input (Joules/Liter) ¾ %Gasoline decreases as total fuel input increases. ¾ At some point there is a crossover between roughness limited minimum gasoline fraction and knock limited maximum gasoline fraction. The crossover occurs at 12:1 CompressionCompression Ratio. KnockKnock andand RoughRough LimitLimit CrossoverCrossover –– E85E85 100 90 Rough Limit E85 80 70 8:1 Knock Limit 60 E85 10:1 Knock 50 Lim it E85 40 12:1 Knock 30 Limit E85 20 14:1 Knock LHV basis % E85 10 Limit E85 0 0 500 1000 1500 2000 2500 3000 3500 4000 Total Specific Fuel Input (J/l) The Crossover occurs at 13.5:1 Compression Ratio. ThermalThermal EfficiencyEfficiency AtAt RoughRough LimitLimit Gasoline E85 40 40 35 35 30 8:1 30 8:1 25 25 10:1 20 20 15 eeds 10:1 p 15 s 10 12:1 Net Indicated Indicated Net 10 5 12:1 5 Thermal%,All speeds Thermal%,All 0 0 Net Indicated Thermal%,All Thermal%,All Indicated Net 0 200 400 600 800 0 100 200 300 400 500 600 700 IMEPn IMEPn SummarySummary ofof Ethanol/NH3Ethanol/NH3 CombustionCombustion putput intointo figurefigure……FuelFuel MixMix SweepSweep atat 16001600 RPM,RPM, 10:110:1 andand IMEPIMEPn ~~ 550550 kPa.kPa. 100 90 80 Spark Advance(deg) 70 Ignition Delay(deg) 60 50 Burn Duration(degrees) 40 Net Indicated 30 Thermal% COV(IMEPn)% 20 10 0 0 20 40 60 80 100 120 ConclusionsConclusions ¾ TheThe knockknock andand roughrough limitlimit crossovercrossover occursoccurs atat ~13.5:1~13.5:1 forfor E85E85 andand ~12:1~12:1 forfor gasoline.gasoline. ¾ E85/NH3E85/NH3 hashas higherhigher knockknock limitlimit andand allowsallows forfor aa higherhigher maximummaximum compressioncompression ratioratio andand thermalthermal efficiency.efficiency. ¾ Gasoline/NH3Gasoline/NH3 hashas aa lowerlower roughnessroughness limitlimit andand allowsallows forfor aa slightlyslightly moremore fuelfuel mixturemixture flexibility.flexibility. ¾ TheThe roughnessroughness limitedlimited promoterpromoter fractionfraction isis foundfound toto bebe almostalmost thethe samesame forfor bothboth (Ethanol(Ethanol &Gasoline)&Gasoline) whenwhen usedused withwith AmmoniaAmmonia asas thethe primaryprimary fuel.fuel. ¾ TheThe fuelfuel blendblend doesdoes notnot changechange muchmuch withwith speed.speed. ¾ E85E85 isis anan attractiveattractive combustioncombustion promoter,promoter, likelike gasoline,gasoline, whenwhen usedused withwith ammoniaammonia asas thethe primaryprimary 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.