DIESEL OXIDATION CATALYST CONTROL OF PM, CO AND HC FROM REACTIVITY CONTROLLED COMPRESSION IGNITION COMBUSTION

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1 DIESEL OXIDATION CATALYST CONTROL OF PM, CO AND HC FROM REACTIVITY CONTROLLED COMPRESSION IGNITION COMBUSTION Vitaly Prikhodko, ScoC Curran, Jim Parks and Robert Wagner Fuels, Engines and Emissions Research Center Oak Ridge NaMonal Laboratory Gurpreet Singh, Ken Howden Office of Vehicle Technologies U.S. Department of Energy 2013 DOE CLEERS Workshop April 10-12, 2013

2 Precise control of the combusmon process allows for high efficiency and low emissions LTC creates reacting mixtures in-cylinder that avoid soot and NOx formation while at the same time avoid CO and UHC emissions. Charge must end up in this region after combustion is complete DOE CLEERS Workshop Slide adapted from DOE presenta<on, Gurpreet Singh et al.

3 Dual- fuel ReacMvity Controlled Compression IgniMon () allows increased engine operamng range for premixed combusmon through: Global fuel reac9vity (phasing) Fuel reac9vity gradients (pressure rise) Equivalence ra9o stra9fica9on Temperature stra9fica9on offers both benefits and challenges to implementamon of LTC Diesel- like efficiency or befer Low NOx and soot Controls and emissions challenges Low = Prevents Auto- Igni9on Fuel ReacMvity High = Promotes Auto- Igni9on Gasoline PFI Stoich GDI Lean GDI Gasoline HCCI PPC Diesel HCCI PCCI DI Diesel DOE CLEERS Workshop

4 Diesel- like (or becer) efficiency with reducmons in both NOx and PM Peak BTE within light- duty drive cycle range (becer than peak BTE of 1.9L GM diesel) Low NOx across BTE Has the potenmal to improve fuel economy by 15% over best- in- class PFI ORNL Simulated and EPA FTP Fuel (UDDS) Economy 2009 compared PFI Fuel to Economy PFI gasoline Data Fuel Economy Data Modeled Fuel Economy Near zero smoke number (not zero PM) PFI Data for small to full-size passenger cars with varying vehicle weight DOE CLEERS Workshop Data from Curran et al will be presented at 2013 SAE World Congress

5 PM with uniquely different morphology and chemistry Lack of appearance of black carbon in suggests differences in chemical composition Qualitative comparison of similar masses à particles shown to be mostly organic rather than elemental carbon Engine Condition: 2300 rpm, 4.2 bar BMEP Conventional PM Mass (mg/min)* DOE CLEERS Workshop PCCI SAE

6 Gasoline- like HC and CO emission levels but at much lower exhaust temperatures HC Exh Temp T<200⁰C CO DOE CLEERS Workshop

7 presents different emission challenges Conventional Diesel Engine Out Emissions NOx PM HC CO Catalytic Control Options SCR DPF DOC and/or LNT + + Engine Out Emissions Catalytic Control Options NOx PM HC SCR OC and/or LNT + CO DOE CLEERS Workshop

8 EffecMveness of a DOC to control PM, CO and HC from engine based on 2007 GM 1.9- L mulm- cylinder diesel engine Dual- fuel system with PFI injectors for gasoline OEM diesel fuel system OEM variable geometry turbocharger DRIVVEN control system with DCAT Full control of diesel & gasoline fuel systems Cylinder- to- cylinder balancing capability Exhaust aftertreatment Model DOC 100 g/ft 3 Pt, 1.25-liter ORNL Multi-Cylinder 1.9L GM CIDI Number of Cylinders 4 Bore, mm 82.0 Stroke, mm 90.4 Compression RaMo 17.5 Rated Power, kw 110 Modified Intake Manifold with PFI Injectors Rated Torque, Nm DOE CLEERS Workshop

9 PM mass reduced by ~50% Particle Mass Emissions (g/hp-hr) Cell 2, Condition: 6-7, 6-9, 6-10, engine Engine 2300GM rpm, 4.2 bar BMEP 0.14 Reduction by DOC Conventional Diesel: 30 ± 6% Diesel PCCI: 9 ± 18% Dual-Fuel : 47 ± 9% Engine-out PCCI and mass are similar in magnitude but % PM mass reduction in PCCI compared to 50% in DOC effective despite low exhaust temperature 0.04 Conventional: 411 C PCCI: 408 C 0.02 : 247 C Engine Post Post Out DOC DOC Conventional Diesel Diesel PCCI Engine 1 Out Engine 5 Out Post 6 DOC PCCI Dual-Fuel post-doc emissions ± g/hp-hr DOE CLEERS Workshop Conv 7 PM Mass (mg/min)*

10 PM Nuclei mode number concentration reduced 35 ± 6% by DOC dn/dlogd p (#/cm 3 ) 1e+9 1e+8 1e+7 1e+6 1e+5 Conv: Engine Out Conv: Post DOC PCCI: Engine Out PCCI: Post DOC Dual: Engine Out Dual: Post DOC 1e d p (nm) accumulamon mode (>30 nm) ~100 Mmes less than Conv and PCCI Enhanced fuel and air mixing High HC concentra9on with lack of soot surface area for adsorp9on Nuclei mode is susceptible to vaporization and oxidation at 250 C given high surface tension Engine Condition: 2300 rpm, 4.2 bar BMEP DOE CLEERS Workshop

11 HC species are quite different from Conv. CombusMon Engine Condition: 2300 rpm, 4.2 bar BMEP * * * Considerable increase in carbonyl emissions for dual- fuel DisproporMonal increase in mono- aromamc carbonyls (Gasoline=mono- aromamc rich, diesel=mono- aromamc poor) Gasoline to diesel ratio changes over the speed/load map, the chemical composition will shift from diesel-like to gasoline-like HCs and vice versa which may pose a challenge for a oxidation catalyst DOE CLEERS Workshop SAE

12 results in shil in HC and CO light- off temperature 1250 rpm engine out CO is 5x higher engine out HC is 4x at lower loads and 11 Mmes at higher loads Lower exhaust temperatures Speed/Load rpm/bar ΔT C 1250/ / / / rpm Conversion (%) HC () No catalyst acmvity in CO () below 200 C HC (CDC) CO (CDC) Shil to higher HC and CO light- off in Inlet Exhaust Temperature (C) 80% HC and 100% CO conversion at 190 C at convenmonal combusmon DOE CLEERS Workshop

13 Summary Engine Out Emissions NOx Significant reducmon in engine out NOx and PM emissions PM HC DOC Much higher CO and HC emissions CO Low exhaust temperatures (much <200 C) 50% reducmon in PM by DOC at 250 C Shil to higher HC and CO light- off in No DOC ac9vity below 200 C and near complete CO and HC removal above 300 C compared to 80% HC and 100% CO conversion at 190 C at conven9onal combus9on DOE CLEERS Workshop

14 Mapping Data is available at CLEERS website Efficiency and emissions map of gasoline and diesel hcp:// BMEP (bar) Diesel Rate (g/s) Gasoline rate (g/s) Max COV (%) Raw BSFC (g/kwhr) D_eq BSFC (g/kwhr) AirMassFlo w (g/s) Speed (RPM) Torque (ft- lb) Gas % (mass) BTE (%) BaroP (InHg) EGR Rate (%) AFR mass HC (ppm) NOx (ppm) CO (ppm) Boost MPR HC Ex T CO2 Intake (%) DOE CLEERS Workshop