Effect of Air- Fuel Ratio on Engine- Out Exhaust Hydrocarbon Species from a Direct Injected Gasoline Engine. April 6, 2016

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Effect of Air- Fuel Ratio on Engine- Out Exhaust Hydrocarbon Species from a Direct Injected Gasoline Engine April 6, 2016 Stani Bohac, Jason Gaudet, John

1 Effect of Air- Fuel Ratio on Engine- Out Exhaust Hydrocarbon Species from a Direct Injected Gasoline Engine April 6, 2016 Stani Bohac, Jason Gaudet, John Hoard University of Michigan 2016 DOE- Crosscut Lean/Low- Temperature Exhaust Emissions Reduction Simulation (CLEERS) Workshop April 6-8, 2016 Ann Arbor, Michigan 1

2 Why Bother with Hydrocarbon Speciation? Low volatility HC and particulates nucleate to form ultra-fine particles (<100 nm) condense (dew point) or adsorb (van der Walls forces) onto existing particles Particulate properties EGR cooler fouling filtration efficiency and regeneration of a GPF performance of exhaust particle sensors (conductivity, collection efficiency, etc.) Olefins and acetylenes high concentrations relative to oxygen displace oxygen and can temporarily deactivate a Pt-based catalyst at low temperatures C 3 H 6 can reduce NO x conversion on an Fe-zeolite SCR catalyst cycled between reducing and oxidizing (LNT-SCR or TWC-SCR) Paraffins slightly higher oxidation catalyst light-off temperature Methane not included in NMOG but is a greenhouse gas 2

3 Methane Properties of Hydrocarbon Classes Very stable and difficult to oxidize in a catalyst or atmosphere (10 yr in atm) Extremely low SMOG impact (0.01 go 3 /ghc) and not included in NMOG Significant greenhouse gas (methane GWP 25X CO 2 ) Paraffins (e.g., 2,3,3-trimethylpentane) Relatively stable & not the easiest to oxidize in a catalyst or atm (4 days in atm) Low SMOG impact (1.2 go 3 /ghc for 2,3,3-trimethylpentane) Olefins and acetylenes (e.g., propene) Easy to oxidize in a catalyst or atmosphere (15 hr in atm) Can deactivate a catalyst High SMOG impact (12 go 3 /ghc) Aromatics (e.g., m-xylene) Most are easy to oxidize in a catalyst or atmosphere (15 hr in atm) High SMOG impact (11 go 3 /ghc) Oxygenates (e.g., formaldehyde) Easy to oxidize in catalyst and atmosphere (3 hr in atm) Moderate/High SMOG impact (9 go 3 /ghc) 3

4 Prior Investigations PFI engines Papa (SAE ) Pioneering work Kaiser et al. (J of High Res Chomatography, v17, p264, 1994) effect of engine operating condition HCCI engines Kaiser et al. (SAE ) effect of A/F ratio Lean stratified GDI engines Cole et al. (SAE ) Asian market Mitsubishi Legnum Kaiser et al. (SAE ) effect of start of injection timing (i.e., mixing) Stoichiometric GDI engines May et al. (Atm Env, v88, p247, 2014) median of 64 vehicles but only 2 are GDI Hasan et al. (Atm Env, v129, p210, 2016) 8 hydrocarbon species from wall-guided GDI Ø only 8 species Ø Didn t vary λ 4

5 Objective Speciate engine-out gaseous hydrocarbons from a GDI engine operated rich, stoichiometric, and lean to provide information for other studies on the effects HC species on particulates, EGR cooler fouling, aftertreatment, and sensors. 5

6 Experimental Setup Engine Test engine GM Ecotec LNF 2.0L DISI turbocharged I4 engine (MY2010) Bore x Stroke x Con Rod x Wrist Pin Offset: 86 mm x 86 mm x mm x 0.8 mm CR: 9.2:1 Performance: rpm rpm (22 bar BMEP) Fuel injection: side mounted injector wall guided spray Bosch HDEV5 injectors, 22.5 cc/s 100 bar bar Boosting: Borg Warner twin scroll K04 turbocharger maximum turbine-in T= 980 C maximum boost = 20 psig Valve timing: dual VVT with 50 CA phasing authority 10.3 mm intake and exhaust valve lift Fuel/oil: 93 octane E10 premium unleaded 5W-30 Mobile 1 synthetic lubricating oil 6

7 Experimental Setup Fuel Premium Unleaded E10 Pump Gas supplied by Corrigan Oil, analysis by Paragon Laboratories (Livonia, MI) Octane: 99.4 RON, 91.3 MON, 95.4 AKI, 8.1 sensitivity LHV: Density: HC type (FIA): Elemental analysis: Oxygenates by GC: Vapor pressure: Distillation: MJ/kg g/ml 83.0% saturates, 0.9% olefins, 6.0% aromatics (% v/v) 80.89% carbon, 15.05% hydrogen, 4.06% oxygen (% m/m) ethanol (% v/v) psi DVPE (ASTM) 10% at 47.9 C, 50% at 96.7 C, 90% at C (Class E winter fuel) 7

8 Experimental Setup Emissions Horiba Mexa-One THC by FID Shimadzu GC-17A HC speciation by capillary column and FID MKS 2030HS FTIR Oxygenated and low molecular weight HC speciation by FTIR 8

9 130 Species Library, C 1 C 10 methane t-2-pentene c-2-hexene 3-ethyl-c-2-pentene c-2-octene ethene 3,3-dimethyl-1-butene 2-methyl-c-2-pentene 2,4,4-trimethyl-1-pentene 2,3,5-trimethylhexane acetylene c-2-pentene 2,2-dimethylpentane 2,3-dimethyl-2-pentene 2,4-dimethylheptane ethane 2-methyl-2-butene methylcyclopentane c-2-heptene c-1,2-dimethylcyclohexane propene cyclopentadiene 2,4-dimethylpentane methylcyclohexane ethylcyclohexane propane 2,2-dimethylbutane 2,2,3-trimethylbutane 2,2-dimethylhexane 3,5-dimethylheptane propadiene cyclopentene 3,4-dimethyl-1-pentene 2,4,4-trimethyl-2-pentene ethylbenzene 2,5-dimethylhexane & propyne 4-methyl-1-pentene benzene ethylcyclopentane 2,3-dimethylheptane 2-methylpropane 3-methyl-1-pentene 3-methyl-1-hexene 2,4-dimethylhexane m&p-xylene 2-methylpropene cyclopentane 3,3-dimethylpentane 3,3-dimethylhexane 2-methyloctane & 4- methyloctane 1-butene 2,3-dimethylbutane cyclohexane 2,3,4-trimethylpentane 3-methyloctane 1,3-butadiene MTBE (C5H12O) 2-methylhexane toluene styrene n-butane 4-methyl-c-2-pentene 2,3-dimethylpentane 2,3,3-trimethylpentane o-xylene methanol 2-methylpentane cyclohexene 2,3-dimethylhexane 1-nonene t-2-butene 4-methyl-t-2-pentene 3-methylhexane 2-methylheptane n-nonane 2,2-dimethylpropane biacetyl 3-pentanone 4-methylheptane i-propylbenzene 1-butyne 3-methylpentane c-1,3- dimethylcyclopentane 3-methylheptane 2,2-dimethyloctane c-2-butene 2-methyl-1-pentene 3-ethylpentane 1-c,2-t,3- trimethylcyclopentane benzaldehyde 3-methyl-1-butene 1-hexene t-1,2-dimethylcyclopentanec-1,3-dimethylcyclohexane2,4-dimethyloctane 2-methylbutane n-hexane 1-heptene t-1,4-dimethylcyclohexane n-propylbenzene ethanol t-3-hexene 2,2,4-trimethylpentane 2,2,5-trimethylhexane 1-methyl-3-ethylbenzene 2-butyne c-3-hexene t-3-heptene 1-octene 1-methyl-4-ethylbenzene 1-pentene t-2-hexene n-heptane t-4-octene 1,3,5-trimethylbenzene 2-methyl-1-butene 3-methyl-t-2-pentene 2-methyl-2-hexene n-octane 1-methyl-2-ethylbenzene n-pentane 2-methyl-2-pentene 3-methly-t-3-hexene t-2-octene 1,2,4-trimethylbenzene 2-methyl-1,3-butadiene 3-methylcyclopentene t-2-heptene t-1,3-dimethylcyclohexane n-decane Methane in gray;; Paraffins in black;; Olefins in red;; Aromatics in blue;; Oxygenates in green 9

10 Test Conditions λ (-) Speed (rpm) BMEP (bar) Spark ( BTDC) CA of P max ( ATDC) SOI ( BTDC firing) P rail (bar) EVC * ( ATDC) IVO * ( BTDC) BSFC (g/kwh) T cyl.1-exh ( C) T turb-out ( C) * at 0.25 mm lift 10

11 Energy Balance and Standard Exhaust Species 11

12 Energy Balance Combustion Efficiency (%) Comb. Eff. (%) % fuel energy in CO % fuel energy in HC (from GC) Fuel Energy in CO and HC (%) Lambda (- ) Combustion efficiency best with λ=1.10 For λ=0.90 more energy in CO than HC. For λ=1.10 more energy in HC than CO. 12

13 Temperature and Standard Exhaust Species Turbine- Out T ( C) NOx and THC (ppm, ppmc1) NOx (ppm) GC THC (ppmc1) CO (%) 13 turbine- out T ( C) O2 (%) Lambda (- ) O2 (%) CO (%)

14 Speciation Results (GC+FTIR) 14

15 Hydrocarbon Speciation for λ = 0.90 Peak Result ppmc1 mghc/s mghc/gfuel Confidence 60unidentified unidentified 1methane High Probability 2ethene High Probability 3acetylene High Probability 322,3,3- trimethylpentane High Probability 5propene High Probability 282,2,4- trimethylpentane High Probability 92- methylpropene High Probability 44m&p- xylene High Probability 312,3,4- trimethylpentane High Probability 56unidentified unidentified 39unidentified unidentified FTIRethanol (C2H6O) n- butane High Probability 362,2,5- trimethylhexane High Probability FTIRacetaldehyde (C2H4O) FTIRMTBE (C5H12O) ,2,4- trimethylbenzene Low Probability 531- methyl- 4- ethylbenzene Low Probability 57unidentified unidentified 142- methylbutane High Probability 151- pentene High Probability 46unidentified unidentified 61n- decane High Probability 272,3- dimethylpentane High Probability 4ethane High Probability 54unidentified unidentified 42unidentified unidentified 58unidentified unidentified 332,3- dimethylhexane High Probability 302,4- dimethylhexane High Probability 263- methyl- 1- hexene Low Probability 15

16 Hydrocarbon Speciation for λ = 0.90 continued Peak Result ppmc1 mghc/s mghc/gfuel Confidence 55 unidentified unidentified 29 2,5- dimethylhexane & ethylcyclopentane High Probability 25 2,4- dimethylpentane High Probability 45 unidentified unidentified FTIRformaldehyde (CH2O) ,3- butadiene High Probability methyl- 2- butene High Probability 12 t- 2- butene High Probability 52 n- propylbenzene High Probability 21 2,3- dimethylbutane High Probability methylpentane High Probability 8 propyne High Probability 40 2,4- dimethylheptane High Probability 34 unidentified unidentified 38 2,3,5- trimethylhexane Low Probability nonene High Probability 51 unidentified unidentified 37 n- octane High Probability methyl- 1,3- butadiene Low Probability 49 2,2- dimethyloctane High Probability 13 c- 2- butene High Probability 7 propadiene High Probability methyl- 1- butene Low Probability methylpentane High Probability 48 unidentified unidentified methylheptane High Probability 41 unidentified unidentified 17 n- pentane Low Probability 24 methylcyclopentane High Probability 43 2,3- dimethylheptane High Probability FTIRmethanol (CH4O) unidentified unidentified 20 cyclopentadiene Low Probability 6 propane High Probability

17 Hydrocarbon Speciation for λ = 1.00 Peak Result ppmc1 mghc/s mghc/gfuel Confidence 53 unidentified unidentified 5 propene High Probability 2 ethene High Probability 9 2- methylpropene High Probability 31 2,3,3- trimethylpentane High Probability 1 methane High Probability 26 2,2,4- trimethylpentane High Probability 35 unidentified unidentified 54 n- decane High Probability 37 m&p- xylene High Probability FTIRMTBE (C5H12O) FTIRacetaldehyde (C2H4O) ,3,4- trimethylpentane High Probability FTIRformaldehyde (CH2O) acetylene High Probability 49 unidentified unidentified 11 n- butane High Probability FTIRethanol (C2H6O) methyl- 4- ethylbenzene High Probability 4 ethane High Probability pentene Low Probability methylbutane Low Probability 33 2,2,5- trimethylhexane High Probability 39 unidentified unidentified 10 1,3- butadiene High Probability 47 unidentified unidentified 25 2,3- dimethylpentane High Probability 36 unidentified unidentified 50 unidentified unidentified 53 unidentified unidentified 5 propene High Probability 2 ethene High Probability 17

18 Hydrocarbon Speciation for λ = 1.00 continued Peak Result ppmc1 mghc/s mghc/gfuel Confidence 41n- nonane High Probability 521,2,4- trimethylbenzene Low Probability 182- methyl- 2- butene High Probability 34n- octane High Probability 172- methyl- 1,3- butadiene Low Probability 12t- 2- butene High Probability 292,4- dimethylhexane High Probability 322,3- dimethylhexane High Probability 48unidentified unidentified 38unidentified unidentified 8propyne High Probability 243- methyl- 1- hexene Low Probability 192,3- dimethylbutane High Probability 232,4- dimethylpentane Low Probability 282,5- dimethylhexane & ethylcyclopentane High Probability 44unidentified unidentified 7propadiene High Probability 212- methylpentane Low Probability 13c- 2- butene Low Probability 51unidentified unidentified 45n- propylbenzene High Probability 162- methyl- 1- butene Low Probability 20MTBE (C5H12O) High Probability FTIRmethanol (CH4O) n- heptane High Probability 401- nonene High Probability 432,2- dimethyloctane High Probability 42unidentified unidentified 223- methylpentane High Probability 6propane High Probability 18

19 Hydrocarbon Speciation for λ = 1.10 Peak Result ppmc1 mghc/s mghc/gfuel Confidence 50 unidentified unidentified 5 propene High Probability 2 ethene High Probability 9 2- methylpropene High Probability 51 n- decane High Probability FTIRformaldehyde (CH2O) unidentified unidentified 29 2,3,3- trimethylpentane High Probability FTIRMTBE (C5H12O) ,2,4- trimethylpentane High Probability FTIRacetaldehyde (C2H4O) m&p- xylene High Probability 28 2,3,4- trimethylpentane High Probability FTIRethanol (C2H6O) n- butane High Probability 39 n- nonane High Probability 15 unidentified unidentified 3 acetylene High Probability 1 methane High Probability 46 unidentified unidentified 32 n- octane High Probability methylbutane Low Probability methyl- 4- ethylbenzene Low Probability 37 unidentified unidentified 10 1,3- butadiene High Probability 31 2,2,5- trimethylhexane High Probability methyl- 2- butene High Probability 41 unidentified unidentified 19

20 Hydrocarbon Speciation for λ = 1.10 continued Peak Result ppmc1 mghc/s mghc/gfuel Confidence 44 unidentified unidentified methyl- 1,3- butadiene Low Probability 12 t- 2- butene High Probability 23 2,3- dimethylpentane High Probability 34 unidentified unidentified 47 unidentified unidentified 49 1,2,4- trimethylbenzene Low Probability 19 2,3- dimethylbutane Low Probability 25 n- heptane High Probability 30 2,3- dimethylhexane High Probability 27 2,4- dimethylhexane High Probability 4 ethane High Probability 36 unidentified unidentified 45 unidentified unidentified 21 2,4- dimethylpentane Low Probability 8 propyne High Probability methyl- 1- butene Low Probability 13 c- 2- butene Low Probability 7 propadiene High Probability 48 unidentified unidentified 26 2,5- dimethylhexane & ethylcyclopentane High Probability 42 n- propylbenzene High Probability methylpentane High Probability methyl- 1- hexene Low Probability FTIRmethanol (CH4O) nonene High Probability 40 unidentified unidentified 6 propane High Probability 20

21 Hydrocarbon Speciation: Top 5 Identified Species Methane Propene Propene 144 ppmc ppmc 1 93 ppmc 1 Ethene Ethene Ethene 115 ppm C 1 92 ppmc 1 74 ppmc 1 Acetylene 2-Methylpropene 2-Methylpropene 105 ppmc 1 76 ppmc 1 65 ppmc 1 2,3,3-trimethylpentane 2,3,3-trimethylpentane n-decane 92 ppmc 1 60 ppmc 1 61 ppmc 1 Propene Methane Formaldehyde (CH 2 O) 85 ppmc 1 50 ppmc 1 56 ppmc 1 Top identified species: Methane for λ=0.90 (oxidation process runs out of oxygen) Propene for λ=1.00 and 1.10 (temperature quenching of crevice HC reactions) 21

22 Prominent Fuel HC Appear Prominently in Exhaust HC Top 6 fuel species (ppmc 1 basis) are: 2,2,4-trimethylpentane 2,3,4-trimethylpentane 2,3,3-trimethylpentane n-butane 2-methylbutane ethanol They account for 54% of the fuel by weight. These 6 HC species are among the highest concentration exhaust species (ppmc 1 ) for λ=0.90, 1.00, and

23 Hydrocarbon Classes Total Concentrations of Identified HC Concentration (ppmc 1 ) paraffins olefins aromatics oxygenates Lambda (- ) Leaner operation reduces paraffins, olefins, and aromatics Leaner operation increases oxygenates (greater abundance of O 2 ) At each lambda, paraffins and olefins dominate aromatics and oxygenates 23

24 Hydrocarbon Classes Fraction of Total Identified HC Fraction of Total Identified HC (%C1) paraffins olefins aromatics oxygenates Lambda (- ) Fractions of paraffins and aromatics decrease as mixture becomes leaner. Fraction of oxygenates increases as mixture becomes leaner (greater abundance of O 2 ). 24

25 Exhaust Gas Hydrocarbon Composition (Molar Average) λ=0.90 λ=1.00 λ=1.10 C:H:O CH 2.20 O CH 2.15 O CH 2.11 O molecular weight (g/mol) molecular composition C 2.91 H 6.41 O C 3.13 H 6.74 O C 3.13 H 6.60 O During rich combustion, many exhaust HC come from oxidation that was halted by oxygen deficiency. Ø low MW (high fraction of methane) Ø H:C ratio same as the fuel Ø O:C ratio same as the fuel Fuel C:H:O is CH 2.22 O Very close to rich exhaust C:H:O During lean combustion, many exhaust HC come from crevice HC oxidation that was halted by low temperature during expansion. Ø higher MW (low fraction of methane;; larger partial oxidation products) Ø H:C ratio slightly lower than the fuel (lower fraction of paraffins) Ø O:C ratio significantly higher than the fuel (higher fraction of oxygenates) 25

26 Low Volatility Hydrocarbons 26

27 Effect of Lambda on High, Medium, and Low Volatility HC* Concentration (ppm HC) high volatility HC (C1- C4) medium volatility HC (C5- C8) low volatility HC (C9- C10) Lambda (- ) Leaner operation reduces concentrations of high, medium, and low volatility HC The majority of exhaust HC molecules are high volatility HC * HC only (no oxygenates) 27

28 Effect of Lambda on Exhaust Hydrocarbon Vapor Pressure* 0.6 THC Vapor Pressure (mbar) C9- C Lambda (- ) Leaner operation reduces vapor pressure of THC and low volatility HC (C 9 -C 10 ) * HC only (no oxygenates) 28

29 HC Condensation and Adsorption* 0.6 Psat of n- decane (mbar) λ=1.10 λ=1.00 λ= Temperature ( C) Even if all HC were n-decane, HC condensation/nucleation will not occur above 4 C for λ=0.90. HC adsorption onto existing particulates is possible (van der Waals forces). Recommend quantifying C 9 -C 10 HC found on particulates. * HC only (no oxygenates) 29

30 Summary and Conclusions Energy balance and standard exhaust gases Combustion efficiency reached 99.0% at λ=1.10 At λ=0.90, more energy in CO than in HC. At λ=1.00 and 1.10, more energy in HC than in CO. Hydrocarbon Speciation Highest concentration species: λ=0.90: methane (oxidation runs out of oxygen) λ=1.00 and 1.10: propene (quenching of crevice HC oxidation reactions) Exhaust hydrocarbon composition: At λ=0.90: CH 2.20 O MW=43.2 g/mol At λ=1.00: CH 2.15 O MW=47.8 g/mol At λ=1.10: CH 2.11 O MW=50.0 g/mol Paraffins, olefins and aromatics decrease with leaner mixture Oxygenates increase with leaner mixture Low volatility hydrocarbons At the conditions tested, HC condensation/nucleation will not occur above 4 C HC adsorption is possible 30

ANALYSIS OF GASOLINE RANGE HYDROCARBONS ON BP1-PONA

PET 01 - PETROLEUM ANALYSIS OF GASOLINE RANGE HYDROCARBONS ON BP1-PONA GASOLINE RANGE HYDROCARBONS Column Part No.: 054950 BP1, PONA 50 m x 0.15 mm ID Initial Temp.: 30 C, 5 min hold Rate 1: 2 C/min Temp.