Particle emissions from vehicles : Feedback of road transport

Transcription

1 Renewable energies Eco-friendly production Innovative transport Eco-efficient processes Sustainable resources Particle emissions from vehicles : Feedback of road transport Ludovic Noël Research engineer, Fuel, Emissions & Lubricants department Olivier Colin Research engineer, Engine CFD & Simulation department Christian Angelberger Project Leader, Engine CFD & Simulation department

2 Outline Context Evolution of EU emission regulations for road transport Description of particles emitted by vehicles Detailed characterization of particles Solutions to reduce particle emissions CFD modeling at IFPEN Conclusions 2

3 Context Historically, particle emissions have been related to Diesel vehicles and to road transport Due to their demonstrated relationship with health effects, a lot of research studies have been performed to reduce emissions from Diesel engines Comprehension of formation mechanisms Development of technical solutions Useful experience to reduce other sources of particles Other vehicle technologies Air transport 3

4 Context Air quality standards in Europe aims to reduce population exposure to air pollutants PM10, PM2.5, NO2, CO, O3... The Member States should propose an air quality plan to ensure compliance with the limit values Role of transports Emissions from transport have been declining since 1990, but Transport remains an important source for NOx and PM emissions In 2010, the daily limit value for PM10 was exceeded at 33 % of traffic sites across the EU source : European Environment Agency 4

5 PM (g/km) Road transport Evolution of PM emission regulations in Europe Strong reduction of PM emissions from Diesel engines during the last 20 years Euro5&6 PM limit = 4,5 mg/km on NEDC On Board Diagnostics (OBD) limit for Euro6 : 12 mg/km Evolution of EU emission regulations for Light Duty vehicles 0,15 0,1 0,05-96% 1 Euro1 new Diesel vehicle ~ 30 Euro5 Diesel vehicles for PM emissions probably more by taking into account the ageing of vehicles (drifting of nominal emissions) 0 Euro Euro Euro Euro Euro Euro S1 5

6 PM (g/kwh) PM (g/kwh) 6 Road transport Evolution of PM emission regulations in Europe Simultaneously, PM emissions from new types of heavy duty engines have been also strongly decreased Emission durability period extended ( VI : km or 7 years for the last class of vehicles) From Euro IV, OBD required Euro VI regulation introduced off-cycle emissions (OCE) testing requirements Off-Road Diesel engines Drilling rigs, Compressors, Bulldozers, Non-road trucks, Mobile cranes... Emission standards are following the same trend as for HD engines 0,4 0,35 0,3 0,25 0,2 0,15 0,1 0,05 0 Evolution of EU emission regulations for Heavy Duty engines 1 0,8 0,6 0,4 0,2 EuroI StageI 1999 EuroII 1998 StageII 2002 EuroIII 2000 StageIIIA % EuroIV 2005 StageIIIB 2011 EuroV 2008 StageIV 2014 Euro VI 2013 Evolution of EU emission regulations for Non Road engines -95% Transient Testing Steady state testing 19-37kW 37-75kW kW kW

7 Road transport Evolution of PM emission regulations in Europe Health effects related to ultrafine particles have led to further evolution of particle emission regulations Ultrafine particles have a low contribution to the total particle mass, but mainly affect the total particle number Additionally to the regulation of particle mass, a regulation of particle number has been introduced (particle size >23nm) Since 2011 for LD Diesel engines ( #/km, PMP measurement procedure) From 2013 for HD Diesel engines Off-road engines in 2017? 7

8 Road transport Evolution of PM emission regulations in Europe What about spark ignition (SI) engines? Spark Ignition Direct Injection (or GDI) engines can emit a high number of fine particles, sometimes higher than Diesel equipped with DPF Euro6 PN limit A PN emission limit for GDI vehicles has been defined in 2 steps #/km from #/km (= Diesel limit) from 2017 Towards a fuel neutral regulation for particle emissions source : J.Anderson et al.,

9 Particle number (#/km) Particle mass (mg/km) Comparison of LD vehicle technologies NEDC cycle Using a particle filter on Diesel engine leads to a strong reduction of both particle mass and particle number (PMP procedure) Typical values for particle concentration are around 1E5 #/cm3 The GDI vehicle does not comply with future Euro6b standards for particle number New European Driving Cycle (NEDC) Euro 6 limit : 4.5mg/km Diesel Euro3 Diesel + DPF Euro4 GDI Euro5 1.00E+14 NEDC froid 1.00E+13 Euro 6a limit (2014) : 6E12 #/km 1.00E+12 Euro 6b limit (2017) : 6E11 #/km 1.00E E E+09 Diesel Euro3 Diesel + DPF Euro4 GDI Euro5 9 source : IFP Energies nouvelles, 2010

10 Particle emissions from vehicles From primary particles to PM 1, 2.5, 10 Primary particle (1nm-30nm) : Black Carbon or Soot, +metals, ash... Aggregates of primary particles and soluble species (50nm-1µm) Soluble Organic Fraction : condensed HC (PAH, Oxygenated...), Sulfates and Water source : Johnson et al.,

11 Particle emissions from vehicles From primary particles to PM 1, 2.5, 10 The size distribution of particles emitted by internal combustion engine is bimodal Nucleation mode (10-30nm) : poor contribution to the total mass, but up to 90% of the total number Accumulation mode (50nm-1µm) : High contribution to the total mass Soot aggregates emitted by engines and vehicles undergo chemical and physical transformations into the atmosphere and contribute to PM1, PM2,5 or PM10 global concentrations source : D.B.Kittelson.,

12 Detailed characterization The strong evolution of emission regulations requires a detailed characterization of physical and chemical properties of particles The morphology can be analyzed using electronic microscopy (SEM and TEM) Chemical analysis of the soluble organic fraction can be performed using High Performance Liquid Chromatography (HPLC) : Identification of 15 polycyclic aromatic hydrocarbons (PAH) specified by the Environment Protection Agency (EPA) GC-MS, Raman Spectroscopy Diesel engine NEDC GDI engine source : IFP Energies nouvelles, source : IFP Energies nouvelles, 2013

13 Soot Formation in Diesel engines Combustion in Diesel engines is fully heterogeneous Fuel and air are non premixed before combustion Strong heterogeneities of temperature and local equivalence ratio (~fuel/air ratio) Soot is formed into the flame between 1500 and 2000 K for rich conditions Advanced combustion concepts allow reducing both soot and NOx formation High injection pressure (> 2000 bars) Low Temperature Combustion (LTC) Homogeneous Combustion (HCCI) source : J.E.Dec., 2009

14 Identification of reduction solutions Engine technology Fuel injection system Direct injection High injection pressure Multiple injections Injector design (nozzle, holes...) Air management Intake manifolds in-cylinder aerodynamics Combustion chamber Piston geometry Variable Valve Actuation Compression Ratio Low Temperature Combustion Electronic control... source : auto-innovations 14

15 Normalized Concentration dn/dloddp (#/cm 3 ) Identification of reduction solutions After treatment Since Euro5, the low levels of PM limit requires the use of after treatment devices, i.e. Diesel Particle Filter (DPF) for LD vehicles Reduction of % for BC, 70-95% for total PM Reduction of PN by 2 orders of magnitude source : Andersson et al., ,0E+09 1,0E+08 Without DPF With DPF 1,0E ,0E+06 1,0E+05 1,0E+04 1,0E Dp (nm) source : IFP Energies nouvelles, 2013

16 Identification of reduction solutions Alternative fuels Additionally to engine technology and after treatment devices, properties of alternative fuels can be used to enhance PM reduction (mass and/or number) Volatility Evaporation process and mixture formation Aromatic compounds PAH = soot precursors Sulfur level Effect on nucleation process Oxygenated alternative fuels Fatty Acid Methyl Esters (FAME) for Diesel engines or Ethanol for SI engines Paraffinic alternative fuels High cetane number, near zero aromatic content, sulfur free Hydrotreated vegetable Oils (HVO) Synthetic fuels obtained by Fisher Tropsch Process (i.e. XtL fuels : Gas to Liquid (GtL), Coal to Liquid (CtL), Biomass to Liquid (BtL)) Natural Gas 16

17 Normalized concentration dn/dlogdp (#/cm3) Effects of fuel properties (GDI engine) A reference ethanol-free gasoline has been compared to an E10 fuel (containing 10 % ethanol) and to an alkylate synthetic fuel mainly blended from paraffinic compounds The results show that the alkylate fuel leads to a strong reduction of particle concentrations and to the diminution of the particle mean diameter compared to E0 and E10 Pinj=80bar, nominal SOI 7E+06 6E+06 5E+06 4E+06 3E+06 2E+06 1E+06 E0 E10 Alkylate 0E Dp (nm) 17 source : IFP Energies nouvelles, 2012

18 Modeling : A major issue to reduce particle emissions Soot formation models for Diesel applications have been developed for many years New chalenges for industrial applications require an evolution of CFD modeling Model for particle size and number => sectional soot model (SSM) Wide range of thermodynamic conditions Effect of fuel composition (biofuels) => need for detailled chemistry in the model => tabulated chemistry Modelling strategy employed SSM based on [1,2] Coupling of SSM with the tabulated Diesel combustion model VPTHC [3] [1] Netzell K. et al., P. Comb. Inst., 2007 [2] Vervisch-Kljakic P., PhD thesis, IFPEN, 2012 [3] Michel J-B, Colin O., Int. Journal of Eng. Research,

19 CFD modeling Evaluation on an Diesel engine Database Experimental setup Single cylinder Diesel engine (500cc) Particle size distribution measured with DMS 500 Commercial Diesel fuel and surrogate fuel (70% n-decane / 30% alphamethylnaphtalene) : good match in terms of soot emissions Color Red Green Bleue Rpm PMI [bar] F ref 0,45 0,45 0,85 Variation P inj EGR Richesse (t inj ) 19

20 CFD modeling RANS Simulations RANS simulations IFP-C3D code Combustion: VPTHC Soot: SSM Surrogate chemistry from Reaction Design consortium (590 species, 3894 reactions) Quantitative agreement for a majority of points with SSM Peak position and width of SNDF is correctly recovered Mass flow rate 20 Size distribution

21 CFD modeling Space and time evolutions Reference case at 4000rpm time= 30 CAD ATDC Fuel/air ratio (up left) Temperature (up right) Soot mass fraction in sections: 1nm (down left) 20nm (down right) Soot size distribution averaged over the combustion chamber. Reference case at 4000 rpm 21

22 Conclusions The knowledge from road transport and Diesel particles can be useful to reduce particle emissions from other sources Comprehension of formation mechanisms Measurement procedures, Analysis Reduction pathways Particle emissions emitted by road transport have been strongly reduced during the last 20 years Reduction of the particle mass by a factor of ~30 Limitation of ultrafine particles (particle number) The combination of different technical solutions allowed reducing particle emissions from road transport Optimization of the combustion process Development of alternative fuels After treatment devices 22

23 Conclusions Research activities are now focusing on the characterization of ultrafine particles emitted by vehicles Comprehension of the formation mechanisms of soot particles in SI engines Impact of DPF regeneration processes on the emission of ultrafine particles Improvement of prediction models ASMAPE project : Advanced Soot Model for Aeronautics and Piston Engines (IFPEN, SNECMA, PSA, CORIA, CNRS) Requirement of an accurate characterization of the nature of nanoparticles (<50nm) from combustion processes Chemical composition Morphology Identification of sources and comprehension of evolution process Remaining questions What is the relationship between ultrafine particles emitted by vehicles (0-100nm) and PM10? Evolution of atmospheric aerosols 23

24 Renewable energies Eco-friendly production Innovative transport Eco-efficient processes Sustainable resources Renewable energies Eco-friendly production Innovative transport Eco-efficient processes Sustainable resources Photofuels 1st Meeting 11&12 /09/ Braunschweig

25 IFP Energies nouvelles IFPEN IFPEN is a public research and training player It has an international scope, covering the fields of energy, transport and the environment From research to industry, technological innovation is central to all its activities As part of the public-interest mission with which it has been tasked by the public authorities, IFPEN focuses on: - providing solutions to take up the challenges facing society in terms of energy and the climate, promoting the emergence of a sustainable energy mix - creating wealth and jobs by supporting French and European economic activity, and the competitiveness of related industrial sectors 2

26 IFP Energies nouvelles IFPEN At a glance 1,675 people*, including 1,146 researchers (engineers and technicians), based in Rueil- Malmaison and Lyon 123 doctoral and 10 post-doctoral researchers More than 50 professions represented: from geological engineers to powertrain engineers A very high-quality technical environment (testing resources, equipment, supercalculator with a power of 110 Teraflops) Status: state-owned industrial and commercial establishment (EPIC) Funding: state budget and resources provided by private French and foreign partners Budget for 2012: million, including million for R&D In 2012: 12,200 active patents More than 200 articles published in international scientific journals * mean workforce, full-time equivalent 3

27 IFP Energies nouvelles IFPEN 5 complementary strategic priorities RENEWABLE ENERGIES ECO-FRIENDLY PRODUCTION INNOVATIVE TRANSPORT ECO-EFFICIENT PROCESSES SUSTAINABLE RESOURCES ENERGY DIVERSIFICATION REDUCING THE ECOLOGICAL IMPACT ENERGY EFFICIENCY SECURING SUPPLIES DECARBONATION CLIMATE CHANGE: CUTTING CO 2 EMISSIONS SUSTAINABLE DEVELOPMENT Producing fuels, chemical intermediates and energy from renewable sources Producing energy while mitigating the environmental footprint Developing fuel-efficient, environmentallyfriendly transport Producing environmentallyfriendly fuels and chemical intermediates from fossil resources Providing environmentallyfriendly technologies and pushing back the current boundaries of oil and gas reserves 5