Contribution of Gasoline Particulate Filter (GPF) and Lubricant to the TGDi System Solution Dr Ian Bell April 2018
Outline GPFs: The need for change What is a GPF? Engine Oil: Part of the solution Lubricant impact on GPF function Summary
Gasoline Particulate Filters: The Need and the Challenge
Emission Targets Driving Fundamental Shift in Gasoline Vehicle Technology Timeline Toxic Emissions Standards Passenger Cars 1970/90s Control of priority pollutants Adoption of catalysts and engine control Reduce HC, CO, NOx Mid 2010s Fuel Efficiency Improve FE/CO2 emissions Engine downsizing and power enhancement Late 2010s More stringent emission regulations Particulates RDE References L to R: Delphi - Worldwide Emissions Standards, Passenger Cars and Light Duty Vehicles 2017-2018; IHS 2015 report, Corning, Gasoline Particulate Filter: A Overview, 2017 LD Emission Control Symposium
What is a Gasoline Particulate Filter? Alternatively Open or Plugged Passages Particle Filtration (and Catalyst Reaction if coated) Tailpipe Emissions Exhaust gas, including PM10 and PM 2.5 [Source?] Afton image
What is a Gasoline Particulate Filter? continued Gasoline engines generate particulate emission (soot) GPFs are filters, or traps, fitted within the exhaust system of vehicles to catch particulate matter GPFs are not DPFs! HC 2 CO NOx PM HC 2 CO NOx PM HC 2 CO NOx PM Inlet Inlet Inlet Outlet N 2 CO 2 H 2 O Outlet N 2 CO 2 H 2 O Outlet Rege n. N 2 CO 2 H 2 O
GPF: System Optimization for Performance Packaging Particulate Filtration Efficiency Gaseous emission Calibration OBD Requirement Successful deployment of GPF technology needs system optimization for various performance requirements Including the engine lubricant Backpressure/Regeneration Total cost
Effect of Ash on Backpressure Effect of Ash - (Cold Flow Bench) XRF Analysis of Ash in GPFs How Soot and Ash accumulate and are managed can have a marked impact on GPF performance and ultimately vehicle fuel economy Ref.: SAE 2012-01-1241 (Shimoda et al) Backpressure increases with soot and ash accumulation amount Low mileage and dyno aged filters contained far less fully oxidized ash mass than the full useful life (FUL) filter Approximately 50 wt% of the collected ash was not directly related to the oil consumption Ref.: SAE 2017-01-0930 (Lambert et al)
Initial Insights Global emission legislation is driving towards more TGDi engines fitted with GPFs Physical removal and oxidation of carbonaceous particulates Ash (and soot) loading rates / levels are one of several critical factors in GPF efficiency Lubricant formulation characteristics impact GPF filtration efficiency Additive ash contribution
Lubricants: Part of the System Solution
Roles of a Lubricant & Lubricant Additives Lubricate Cool Pressurize Protect the oil Enhance Performance Prevent Wear Reduce Friction Remove Contaminants Modify Oil Properties
Key Lubricant Additives Adding Ash ZDDP (zinc dialkyldithiophosphate) Primary, and most effective anti-wear agent (durability) Used for over 80 years Also most costeffective anti-oxidant Metal Detergents (sulfonate, phenate, salicylate) Keeps engines clean, and neutralises combustionacids. Most chemically efficient way to add base to the lube Range of surface impacts MoDTC (molybdenum dithiiocarbamate) Inorganic friction modifier Increased use since mid- 90s Particularly effective in motored-friction tests (fuel economy)
Lubricant Formulation Balance Emission system durability Low Speed Pre-Ignition Protection 12 Seal compatability 10 Shear stability Aeration Test TBD Wear Protection (Chain Wear) TBD 8 6 4 2 0 Fuel Efficiency Corrosion Protection E-85 Emulsion Retention ILSAC GF-55 ILSAC GF-6A Wear Protection (engine) Engine Oil Volatility Oxidative Thickening Protection Turbo Protection Piston Cleanliness Engine Sludge Control Zero ash lubes are theoretically possible, but practically prohibitive Thankfully, our research evaluations show we don t need to be so drastic We must maintain a holistic approach to lubricant formulating
Initial Insights Certain lubricant additives do add ash to the system These additives perform several roles that are critical to the effective operation of the engine The overall vehicle performance and protection is a complex system Lubricant impacts both the engine and GPF operations We need to consider the best overall solution
Lubricant Impact on GPF: Afton Testing
Lubricant Ash Impact on GPF Function 1.0E+13 WLTC 0.006 12.0 WLTC 9.0 PN(#/km) 1.0E+12 1.0E+11 1.0E+10 1.0E+09 CN 6 PN limit 0.005 0.004 0.003 0.002 0.001 PM (g/km) Max. Backpressure (kpa 10.0 8.0 6.0 4.0 2.0 8.0 7.0 6.0 Fuel consumption (L/100km) 1.0E+08 Fresh 0 Aged 100 Fresh 0 Aged 100 0.000 0.0 Fresh 0 Aged 100 Fresh 0 Aged 100 5.0 OEM High High Ash, Ash System Oil B Low Ash, Ash System Oil B PN PM OEM High Ash, Ash System Oil B Low Ash, System Oil B Max. Backpressure Fuel Consumption No significant difference in PM/PN emission, backpressure and fuel consumption between two lube ash levels in end-of-life performance Poorer particulate filtration rate for unconditioned GPF Clear impact of ashloading on GPF backpressure Note: Full Scale Engine/Vehicle Ash Loading/System Durability Studies Source: Afton data 2017
Reality Check on Green Filtration Efficiency 100% PN Filtration Efficiency (%) 95% 90% 85% 80% 75% Bed filtration Cake filtration Source: API DAP 12/12/17 (Lambert et al) 70% 0 1 2 3 4 5 Ash loading (g/l) Source: Afton data 2017 Green filtration efficiency needs improvement to meet legislation requirements Filtration efficiency improves greatly from bed filtration to cake filtration Ensuring the vehicular emissions for new vehicles with green particulate filters may be a significant challenge
Model Engine Studies on GPF Cores: Formulation Affects Oxidation Maximum soot oxidation rate (%/min) 25 20 15 10 5 Ca Mg y = 1.5637e 0.7616x R² = 0.996 y = 2.3277e 0.2307x R² = 0.7762 0 0.00 1.00 2.00 3.00 4.00 Ca/P or Mg/P (molar ratio) Source: Afton data 2017 PM (soot) oxidation is affected by its composition, temperature, catalyst etc. Increased soot burn-off rate can equate to fuel economy savings Lubricant oil formulation can change oxidation rate Lubricant oil formulation can impact GPF regeneration rate and hence benefit fuel economy
Vehicle Detergent Composition Comparison: Testing Results of PN and FE 1.6E+12 PN (#/mile) 0.004 PM (g/mile) 30.5 FE (mpg) 1.4E+12 30.0 1.2E+12 1.0E+12 8.0E+11 6.0E+11 0.003 0.002 29.5 29.0 28.5 Cold start Hot start A B (Ca) (Ca/Mg) 4.0E+11 0.001 28.0 2.0E+11 27.5 0.0E+00 0.000 27.0 Source: Afton data 2017 Test Protocol: Cold Start US06-soak (1h)-US06-soak (1h)-US06 -soak (1h)-US06-soak (1h)-US06 Driving condition (cold start vs. hot start) has significant impact on both PN and FE Source: Afton data 2017
Summary
Summary Global emission legislation is driving towards more TGDi engines fitted with GPFs Lubricant formulation characteristics impact GPF filtration efficiency The overall vehicle performance and protection is a complex system Lubricant impacts both the engine and GPF operations Generally the industry is gravitating to 0.8% Ash lubricants Balancing engine durability and GPF efficiency requirements Green filtration sees a potential challenge in attaining low PN targets
Acknowledgments Huifang Shao Paul Ransom Guillaume Carpentier Brent Calcut Joe Roos SAE 2016-01-2287 SAE 2017-24-0135 SAE 2017-01-2366 SAE 2018-01-1258
Thank you