Investigation on PM Emissions of a Light Duty Diesel Engine with 10% RME and GTL Blends Hongming Xu Jun Zhang University of Birmingham Philipp Price Ford Motor Company International Particle Meeting, Cambridge University 21 May 2010
Presentation Outline 1. Introduction 2. Experimental System 3. Results and Discussion Effect of 10% RME and GTL blends Effect of Injection strategy 4. Conclusions
1. Introduction
Background Diesel Engine Emissions NO x HC & CO Others Particles Human Health & Environment size Number SN/Mass
Development of legislations g/km *#/km Tier Date CO NO x HC+NO x PM PN* Euro 4 Euro 5 Euro 6 Jan 2005 Sept 2009 Jan 2014 0.50 0.25 0.30 0.025-0.50 0.18 0.23 0.005 6.0 x 10 11 0.50 0.08 0.17 0.0045 6.0 x 10 11 Regulations (EC) No 715/2007 of the European Parliament and the Council, "Emissions-Light Duty Vehicles", Jul, 2009. Compared with Euro 4, Euro 5 confines the emissions further for carbon monoxide (CO), hydrocarbons (HC), oxides of nitrogen (NOx) and Particulates Matter (PM) and the latter two had a 28% and 80% reduction respectively. Particle number
Objective of the present study Emission Reduction A Alternative Fuels (Biodiesel, GTL Diesel, and etc) B NOx control Injection Strategy Pilot Injection 2020 target 10% Fuel Blends with Diesel Particle characteristics
2. Experimental System
Test cell and the Ford Puma engine Bore Stroke Compression Ratio 16.6 Engine Capacity Max Power Max Torque Injector type 86mm, 4 cylinders 94.6mm 2198cc 96KW (±5%)@3500rpm 310.0NM(±5%)@1600-2500rpm Common Rail, Direct Injection
Engine test rig layout Inter-cooler Heat Exchanger
Exhaust Measurement TSI SMPS 3936 Horiba MEXA 7100 DEGR AVL Smoke meter 415SG002
Fuel properties PROPERTY UNIT Diesel RME GTL Diesel Ester content % (m/m) / 99.44 / Density @ 15 C kg/m 3 834.9 883.3 781 Viscosity @ 40 C mm2/s 2.87 4.441 3.1 Flash point C 68.5 171.5 91 Sulphur content mg/kg 8.6 <3.0 <3.0 Carbon residue % (m/m) 0.13 <0.1 <0.3 Cetane number 51.1 51 77 Total contamination mg/kg 6.0 (particulate) 1.6 1.6 Lubricity μm 402 / 612 Distillation (Initial Boiling C 181.3 Point) / 204 Aromatics %,m / / <0.1
Engine Test Modes (A) Mode Engine Speed (rpm) Torque (Nm) Load (%) EGR Valve Opening (%) 1 800 2.1 0.68 0 2 1800 30 9.68 30.91 3 1800 30 9.68 15.45 4 1800 30 9.68 0 5 1800 134 43.23 0 6 3100 35 11.29 18.18 7 3100 138 44.52 0 8 3100 230 74.19 0
Engine Test Modes (B) Mode Engine Speed (rpm) Main SOI (BTDC) BMEP (bar) EGR Idle 800-1 0.68 NO Middle Speed/Load 1800-2.69 5.2 YES High Speed/Load 2500-2.69 7.0 NO Pilot Injection +5º CA 0 (mm 3 /stroke) 1.5mm (mm 3 /stroke ) (b) 3(mm 3 /stroke) Base (c) (f) (a) -5º CA (d) (g) (e)
3. Test Results
A. With 10% RME and GTL blends
Particulate number and mean diameter 10 5 800rpm 1800rpm 3100rpm Diesel RME10 GTL10 70 Diesel RME10 GTL10 Total Concentration(Part/cm 3 ) Mean Diameter (nm) 60 1800rpm 3100rpm Mode 1Mode 2Mode 3Mode 4Mode 5Mode 6Mode 7Mode 8 Engine Mode 50 Mode 2 Mode 3 Mode 4 Mode 5 Mode 6 Mode 7 Mode 8 Engine Mode RME10/ GTL10 Increase of engine load Increase of speed Less EGR Fewer particles Fewer particles, larger size More particles, larger size Fewer particles, smaller size
Smoke 0.7 Diesel RME10 GTL10 0.6 800rpm 1800rpm 3100rpm 0.5 FSN 0.4 0.3 The trend of variation of smoke is not quite the same as the particle numbers 0.2 0.1 0.0 Mode 1 Mode 2 Mode 3 Mode 4 Mode 5 Mode 6 Mode 7 Mode 8 Engine Mode
Non-volatile particles Total Concentration(Part/cm 3 ) 10 6 10 5 800 RPM 1800 RPM -28% -39%-32% -43% -32% -42% -34% -53% 3100 RPM Diesel RME10 GTL10-28% -33% -29% -34% Mean Diameter (nm) 70 60 1800 RPM 3100 RPM Diesel RME10 GTL10 Mode 1 Mode 2 Mode 5 Mode 6 Engine Test Mode 50 Mode 2 Mode 5 Mode 6 Engine Test Mode The non-volatiles number reduction by the alternative fuel blends were all higher than the rates when thermo-dilution was not used
Particulate Size Distribution at 800 rpm, Idle Bimodal mode A general reduction of particles in different sizes Small peak at 20nm when RME10 was used DN/DLogDp(Part./cm 3 ) Diesel RME10 GTL10 10 2 10 100 Diameter (nm)
Particulate Size Distribution at 1800 rpm DN/DLogDp(Part./cm 3 ) 30NM, No EGR 134NM, No EGR DieselMode4 DieselMode5 RME10Mode4 RME10Mode5 GTL10Mode4 GTL10Mode5 Mono-modal feature A general reduction of particles in different sizes The increase of load leads to less nucleation mode particles 10 2 10 100 Diameter (nm)
Particulate Size Distribution at 3100rpm 10 5 DieselMode6 RME10Mode6 GTL10Mode6 10 5 DieselMode7 RME10Mode7 GTL10Mode7 DN/DLogDp(Part./cm 3 ) 35NM, With EGR DN/DLogDp(Part./cm 3 ) 138NM, No EGR 10 2 10 5 10 100 Diameter (nm) DieselMode8 RME10Mode8 GTL10Mode8 10 2 10 100 Diameter (nm) DN/DLogDp(Part./cm 3 ) 230NM, No EGR Particles numbers reduced by RME10 or GTL10 Larger particles with the increase of the load 10 2 10 100 Diameter (nm)
Particulate Size Distribution with different EGR 10 5 DieselMode2 DieselMode3 DieselMode4 10 5 RME10Mode2 RME10Mode3 RME10Mode4 DN/DLogDp(Part./cm 3 ) DN/DLogDp(Part./cm 3 ) 10 2 10 5 10 100 Diameter (nm) GTL10Mode2 GTL10Mode3 GTL10Mode4 10 2 10 100 Diameter (nm) DN/DLogDp(Part./cm 3 ) 1800 RPM More EGR, more nucleation particles some nucleation particles around 10 nm might be reduced 10 2 10 100 Diameter (nm)
Non-volatiles during Warming-up (1) large amount of soot from incomplete combustion. (2) The mutated hydrocarbons during the combustion were likely to quench. Concentration DN/DLogDp(Part./cm 3 ) RME10 1 2 3 4 5 6 10 2 10 100 Diameter (nm)
Particle morphology (1800rpm, 30Nm) (a) Diesel magnification of 10000(b) Diesel magnification of 65000 (c) RME 10 magnification of 10000 (d) RME magnification of 65000 (e) GTL10 magnification of 10000 (f) GTL10 magnification of 65000
Summary and conclusions (A) RME10 and GTL10 can lead to a similar reduction in total particle numbers under various engine conditions but their influences to the particle mean diameters are not clear RME10 and GTL10 reduce the accumulation mode particles and some nucleation particles in the larger size range (>30nm); however, RME 10 could also increase those in the small size range under certain cases (<20nm). Particles from diesel combustion have more clusters than those from the RME10 or GTL10 and the primary particle size of all the three fuels is around 20-50 nm. At 1800rpm, the increase of engine load results in an increase of particle mean diameter and the reduction of particle numbers (differently at 3000rpm); the increase of either engine speed or EGR increases the particle numbers as well as the mean diameters Cold starts could result in much higher non-volatile particles in the nucleation mode.
B. Particles influenced by pilot injection
Effect of pilot injection 5x withoutpilot withpilot 100 withoutpilot withpilot Total Concentration(Part/cm 3 ) 4x 3x 2x 1x Mean Diameter (nm) 80 60 40 20 10 5 0 Idle Middle High Engine Mode 0 Middle Engine Mode Particle number reduction at idle and high speed/load mode, increased by EGR at medium load withoutpilot withpilot 10 5 withoutpilot withpilot High withoutpilot withpilot DN/DLogDp(Part./cm 3 ) 10 2 10 100 Diameter(nm) DN/DLogDp(Part./cm 3 ) 10 2 10 Diameter (nm) 100 10 2 10 100 Diameter(nm) Idle mode Middle mode High mode Larger particles using pilot injection in idle/middle mode DN/DLogDp(Part./cm 3 )
Effects of pilot injection timing Total Concentration(Part/cm 3 ) 5x 4x 3x 2x 1x Base+5BTDC Base Base-5BTDC Mean Diameter (nm) 100 80 60 40 20 Base+5BTDC Base Base-5BTDC 0 Idle Middle High Engine Mode 0 Idle Middle High Engine Mode The advance of the pilot injection leads to a reduction of the particle numbers and mean diameters
Effect of pilot injection quantity 5x pilot 1.5mm 3 /str pilot 3mm 3 /str 100 pilot 1.5mm 3 /str pilot 3mm 3 /str Total Concentration(Part/cm 3 ) 4x 3x 2x 1x Mean Diameter (nm) 80 60 40 20 0 Idle Middle High Engine Mode 0 Middle Engine Mode High DN/DLogDp(Part./cm 3 ) 10 5 SOI (BTDC) 12,1.5mm 3 /str 12,3mm 3 /str 17,1.5mm 3 /str 17,3mm 3 /str DN/DLogDp(Part./cm 3 ) 10 5 18,1.5mm 3 /str 18,3mm 3 /str 23,1.5mm 3 /str 23,3mm 3 /str SOI (BTDC) DN/DLogDp(Part./cm 3 ) 10 2 SOI (BTDC) 21,1.5mm 3 /str 21,3mm 3 /str 26,1.5mm 3 /str 26,3mm 3 /str 10 2 10 2 10 Diameter (nm) 100 10 100 Diameter (nm) 10 Diameter (nm) 100 Idle mode middle mode high mode
Summary and conclusions (B) In the absence of EGR, pilot injection seems to help reduce particle numbers, as in the idle and high speeds. When EGR is applied, as in medium speed/load, the introduction and increase of pilot injection quantities increases both the particle number and mean diameter. The advanced timing of a higher radio of pilot injection tends to reduce the number and diameter of particles. The strategy of pilot injection influences the PM emissions from the pilot combustion and at the same time the main combustion through ignition delay. This effect is less significant with the increase of the engine load and with the advance of the pilot injection timing. It is expected that when the strategy of pilot injection is used for NOx and NVH reduction as for biodiesel, attention will be required to minimise its impact on PM emissions.
Acknowledgement The authors gratefully acknowledge research funding from EPSRC under the grant EP/F061692/1 and TSB under the grant M0597H, industrial support from Jaguar Land Rover, Ford Motor Company and Shell Global Solutions, and contributions to the related research from the Birmingham University, Oxford University including colleagues and students who have worked with us.
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