DIESEL PARTICULATES AND NOx EMISSIONS
Monday 18 – Friday 22 May 2015
PROVISIONAL PROGRAMME
All presentations will be delivered by Professor Gordon Andrews unless stated otherwise.
MONDAY 18 MAY 2015
DIESEL COMBUSTION AND EMISSIONS
08.00
Registration and coffee
08.30
Diesel emissions – introduction to the environmental problems including greenhouse gas
emissions reduction
Overview of environmental concerns from diesel emissions: NOx and ozone, particulates, greenhouse
gases. Review and comparison of HDD and passenger car emissions legislation and test cycles. Turbo
10.00
Coffee
10.15
Diesel engine thermodynamic conditions and turbocharging
11.00
Ignition delay
Ignition delay and its influence on peak pressure and NOx
11.45
The Nissan MK concept with long ignition delays to achieve premixed combustion
12.30
Lunch
13.15
CO emissions and control in diesel engines
NOx formation and control in diesel engines
A review of diesel engine NOx formation and reduction techniques. Diffusion combustion and the two
zone model of NOx formation in near stoichiometric zones in a thin region around the fuel jet. Discussion
of the link between reducing NOx and increasing particulates. The influence of fuel injection parameters
on air/fuel mixing and NOx.
15.00
Tea
15.15
Use of EGR and water for NOx control
Reduction in peak flame temperature and NOx using EGR, reduced influence of EGR for lower powers
and better mixed fuel and air. Problems of achieving EGR in diesels, short and long rout. Long route EGR
with particle trap. Increase in soot emissions with EGR. Influence of EGR on wear and lube oil
contamination. Use of on-line oil cleaning (centrifugal or fine bypass filtration) to control these adverse oil
effects.
16.15
Engine exhaust particles in the atmosphere
Professor David Kittelson, Dept of Mechanical Engineering, University of Minnesota, USA
This is a description of measurements of the character of engine exhaust particles as we actually breathe
them, on and near roadways. A series of measurements using a mobile emission laboratory conducted
for a variety of sponsors over the last ten years will be described.
17.45
End of day one
18.00
Welcome reception in Stables Bar
TUESDAY 19 MAY 2015
ENGINE DESIGN AND LUBE OIL INFLUENCES ON NOx AND PARTICULATE EMISSIONS
08.15
Registration and coffee
08.30
Diesel engine processes that influence particulate formation
The nature of diesel particulates: carbon, unburnt fuel, unburnt lube oil, ash, sulphates plus water. The
particulate composition variation with engine power and emissions test cycle. Combustion processes
and engine design factors that influence particulate carbon emissions: lower overall equivalence ratios
and hence lower carbon for the same power with TCIC engines. Fuel injector operational parameters
that influence mixing and carbon.
09.30
Instruments for particle size measurements
Professor David Kittelson, Dept of Mechanical Engineering, University of Minnesota, USA
An overview of the operating principles and performance of instruments used for measuring particle size
distributions, number concentrations, and surface concentrations, with emphasis on instruments suitable
for engine exhaust particle measurements including instruments for transient particle size analysis.
11.15
Coffee
11.30
Factors influencing carbon formation in diesel engines
Fuel effects using radio-tracers. The importance of equivalence ratio. Cold start and exhaust pipe
particulate deposition influences on particle storage and blow out from catalysts and exhaust systems.
The influence of temperature, pressure and equivalence ratio on soot pyrolysis and oxidation, global
modelling equations for soot formation and oxidation. The route to no soot engine using mixing and
temperature control. The Toyota high EGR rich burn low temperature low soot process.
12.30
13.15
14.00
15.00
15.15
16.30
17.45
TUESDAY 19 MAY 2015 CONT…
UHC, particulate fuel fraction and PAH emissions
Sources of UHC and PAH emissions in diesel engines. The importance of unburnt fuel PAH in the
particulate composition. Reduction of nozzle sac volume for reduced UHC, SOF and PAH. The impact of
nozzle sac volume on spray quality and penetration. Lubrication oil layers as fuel absorption locations
that releases HC late in the combustion process. Combustion chamber carbonaceous deposits as
sources of unburnt fuel and PAH storage.
Lunch
The role of lubricating oil in diesel particulate emissions
A review of the recent literature. Carbon from lube oil, unburnt lube oil, use of gas engine to determine
the overall impact of lube oil on particulate emissions; lube oil consumption, methods to reduce lube oil
consumption, required lube oil consumption in low emission vehicles, lube oil emissions during hot
motoring, soot accumulation in used oil and impact on emissions.
Tea
The lubricant contribution to future low emission engine design
Peter Brett, Consultant, formerly Castrol International
Key areas addressed are fuel economy, exhaust gas recirculation, piston cleanliness and soot, in
conjunction with the requirement to extend oil drain intervals and use exhaust after treatment devices.
Ultrafine and nanoparticle formation by engines
Professor David Kittelson, Dept of Mechanical Engineering, University of Minnesota, USA
A description of current concerns about tiny particles generated by engines, sampling problems, and
representative measurements.
End of day two
WEDNESDAY 20 MAY 2015
INFLUENCE OF DIESEL FUELS AND ADDITIVES ON EMISSIONS
08.15
Registration and coffee
08.30
Sources of variability in exhaust particle emission measurements
Professor David Kittelson, Dept of Mechanical Engineering, University of Minnesota, USA
The reduction of HDD particulate emissions legislation by a factor of 10 in 2007 and equivalent
reductions in passenger car particulate emissions makes the issue to their mass measurement using
conventional dilution tunnel systems very difficult. The problem is made even more difficult by the fact
that most engines that use exhaust filters certify with emissions 5 to 10 times below the already tight
standards. Measurements of mass based particle emissions from engines are subject to a variety of
errors, many associated with sampling artefacts that are not predicted by traditional methods of error
analysis. The new solid number emission measurements required by the EU are much more accurate at
these emission levels and will be described.
10.15
Coffee
10.30
Fuel property influences on diesel emissions
A review of engine test data on fuel effects on particulate, SOF, UHC and NOx emissions. Diesel fuel
sulphur and the sulphate emissions issue. Other reasons for ultra low sulphur fuels. The importance of
the physical fuel properties of density, viscosity and volatility on spray formation, mixing and emissions.
The European EPEFE fuel program and the emission predictors that result from this. Reformulated
diesels – fuels with extreme fuel properties can have significant emissions reductions. GTL fuels and
emissions.
12.15
Lunch
13.00
Fuel borne catalysts for DPF regeneration
Dr Steve Cook, Innospec Limited
The effect of a DPF on regulated and unregulated emissions (PAH and NPAH). Dioxin production and
metal emissions, additive performance criteria, light-off temperature, regeneration rate, exotherm
produced and additive treat rate.
14.00
Oxygenated fuels and biodiesels
The use of 5-20% levels of oxygenates (e.g. DME, diglyme etc.) in diesel fuels. Biodiesels using
diesel/vegetable oil blends are also oxygenated fuels as the vegetable oils contain oxygen carrying
compounds. Ethanol is also an bio-diesel fuel as this can be manufactured from farm crops. The bio
fuels are being encouraged as they are considered to be greenhouse gas neutral. The main impact of
oxygenates is a strong reduction in soot emissions, with little influence on NOx. Their use generally
depends on the taxation status of the diesel and the oxygenates as most oxygenates cost more to
produce that diesel. However, they have strong fiscal incentives for their use in many USA states and
in various countries around the world.
15.00
Tea
15.15
Alternative Diesel Fuels - Production, Properties & Practice
Dr Juhani Laurikko, VTT
WEDNESDAY 20 MAY 2015 CONT…
16.00
Fuel injector deposits control
Dr Steve Cook, Innospec Limited
In 1892 Rudolf Diesel patented a means of producing work from the combustion of fuel which involved
the controlled metering of fuel into the combustion chamber; fuel injection. Ever tightening legislation
to reduce unwanted emissions and improve fuel economy has made the precision of this injection
equipment increasingly important. This presentation reviews aspects of fuel injection equipment, how
its performance is affected by deposit formation and what measures can be taken to minimise deposit
formation.
17.00
Cold start and diesel filter light off options
18.00
End of day three
19.00
Course dinner
THURSDAY 21 MAY 2015
PARTICULATE AND NOx AFTER TREATMENT WITH MINIMUM CO 2 PENALTY
08.15
Registration and coffee
08.30
Oxidation catalysts I – HC and sulphate issues
Claus Goersmann, Johnson Matthey plc
This lecture will give a brief overview of the principles of catalysis, then will consider the requirement to
remove, by catalytic oxidation, gaseous components in the exhaust gas from diesel engines. The effects
of the presence of sulphur components in the gas stream on the performance of the catalyst will be
discussed.
09.30
Oxidation catalysts II – particulate volatile fraction
Claus Goersmann, Johnson Matthey plc
A review of the influence of oxidation catalysts on the volatile fraction of particulates including the
separate influence on the lube oil and fuel fractions. Evidence of higher SOF oxidation efficiency than for
gaseous hydrocarbons, at low catalyst temperatures for high boiling point fuel fractions such as PAH and
for lube oil. Evidence of carbon reduction by the catalyst. Evidence for small NOx reductions by oxidation
catalysts.
10.30
Coffee
10.45
Diesel particle traps – overview
Dr Marty Murtagh, Corning Inc
Volume storage fibre type and wall flow filter type traps. Substrate materials, surface filtration, influence
on particle size, overheating and thermal shock problems, limiting storage capacity in g/litre to avoid
thermal problems during regeneration. Back pressure influences. Ash deposition and trap designs to
minimise this problem.
12.00
Continuously regenerating traps (CRT)
Claus Goersmann, Johnson Matthey plc
Diesel particulates collected onto a DPF (Diesel Particulate Filter) need to be removed by oxidation,
otherwise an unacceptable backpressure will build up. The principles, and some operating experience, of
the Johnson Matthey CRT (Continuously Regenerating Trap) and other related devices will be described.
This system allows the regeneration temperature of carbonaceous particulates to be significantly reduced
compared to direct thermal oxidation.
12.45
Lunch
13.30
SCR Principles – HC, NH3, Urea
Claus Goersmann, Johnson Matthey plc
Use of the fuel used by the engine as a reductant for NOx would be the best solution, but a major
limitation is the size of the temperature operating window of the catalysts that have been investigated for
this system. One technology for the reduction of NOx from diesel engines is by the reaction of the NOx
with ammonia. This reaction is well established in stationary power generating applications, but can also
be adapted for use for the control of NOx in lean burning engine exhaust gas. The principles of this
technology will be discussed in this lecture, and its practical application in the following lecture
14.30
Light duty diesel passenger cars PM and NOx control
Dr Piotr Bielaczyc, BOSMAL Automotive Research and Development Institute Ltd.
Engine out PM and NOx emissions are an inherent disadvantage of Diesel engines. European legislation
is moving in the direction of technology-unspecific emissions limits (i.e. the same for petrol and diesel),
and so Euro 6 (and beyond) poses multiple challenges for control of NOx and PM emissions. The
possible introduction of diesel testing at -7°C and increased focus on real-world emissions are also
important considerations. The full range of remedial options will be briefly reviewed in this presentation,
along with notes on powertrain and vehicle testing and practical considerations.
15.15
Tea
15.30
NOx storage
Claus Goersmann, Johnson Matthey plc
An alternative technology for the control of NOx requires the catalyst to store the exhaust gas NOx under
lean operating conditions, then by the introduction of a spike of fuel, making the system temporarily rich,
the NOx is released again and reduced to nitrogen. This system was originally developed for GDI
applications, where high conversions of NOx are obtained, but is more difficult to adapt to diesel due to
the need for the rich spike. Fuel-sulphur levels are also critically important in this technology.
THURSDAY 21 MAY 2015 CONT…
16.30
Integrated emissions control - 4-way catalysts
Claus Goersmann, Johnson Matthey plc
Review drivers for integrated systems – efficiencies and cost; Combining NOx-trapping with oxidation
and filtration – thermal conflicts; Combining ammonia SCR with oxidation and filtration; Need advanced
SCR catalyst formulations – activity, thermal durability; Chemical conflicts – solutions and production
systems; Combining ammonia from NOx-trapping with SCR – advantages; Integrated ammonia
emissions control; Future integrated directions – technical challenges; Overview/summary of catalytic
diesel emissions control strategies and historical gasoline comparisons – future predictions.
17.30
End of day four
FRIDAY 22 MAY 2015
DIESEL FUEL INJECTION AND ENGINE DESIGN TRENDS FOR LOW NOx, PM and CO 2 EMISSIONS
08.15
Registration and coffee
08.30
Technology of HD Euro VI truck engines and future trends towards improved fuel economy
European engine strategies for Euro 6 and beyond.
10.00
Coffee
10.15
Unit injection and common rail fuel injection systems
Mark Smith, Delphi Diesel Systems
Different Fuel Injection Systems as currently in use will be presented: high pressure rotary pumps, unit
injectors and pump-line-nozzle systems. Their advantages and drawbacks will be discussed with regard
to future requirements within their specific applications.
Different Common Rail Fuel Injections Systems will be explained and their specific advantages to
conventional systems highlighted. The usage of control strategies to enhance the performance of the fuel
injection equipment will be discussed. Future requirements for common rail systems will be presented
and compared to next generation common rail system specifications.
11.30
Modern turbocharger systems
Vishal Seeburrun, Cummins Turbo Technologies Ltd
A review of current turbocharger technology and the interaction of the turbocharger with heavy duty
diesel engine emissions reducing strategies.
12.45
Lunch
13.30
Transient gas and particulate emissions measurements from diesel passenger cars
James Burrell, Cambustion Ltd
Particulates and NOx are some of the most challenging emissions to be treated from modern Diesel
engines. Engine-out NOx is generally controlled via Exhaust Gas Recirculation (EGR). HC and CO can
generally be attenuated with an oxidation catalyst. Diesel Particulate Filters (DPFs) are used to trap and
store particulate matter and are then either passively or actively regenerated (emptied) . Both the engine
and afterteatment controls are very transient and the use of fast response gas or particulate analyzers
can be useful in characterising the transient emissions and the effectiveness of the aftertreatment
systems. This presentation shows some transient data recorded from diesel cold starts, DPF
regenerations and EGR control delays.
14.15
Dr Esmail Karimi, Technomot Engineering Ltd
Homogeneous charge and partially premixed diesel engines for low NOx and low soot emissions
Premixed combustion can give zero soot and NOx from diesels, demonstration that this can only occur
across the power range if maximum power is obtained with a turbocharger strategy that limits the
equivalence ratio at maximum power to around 0.5 (30/1 A/F). Otherwise HCCI is as low power
emissions control option and a different strategy needs to be used at high power outputs. This can be
achieved using common-rail fuel injection systems. Port fuel injected diesels with main fuel injection,
100% port injection, early in-cylinder injection with main injection, 100% early injection. Problems of fuel
economy, hydrocarbon and CO emissions. Problems of control of start of combustion if conventional
main injection is not used, use of EGR and water injection to retard the auto ignition problem.
15.15
Tea
15.30
Large diesel engines for railway, marine and electric power generation with low NOx,
PM and low CO2
16.30
SNCR: SCR - urea mixing and control; influence on PM
SNCR reduces NOx without a catalyst: principles and application are reviewed. Open loop and closed
loop control of urea addition in transient cycles. Use of non-optimum Urea/NOx ratios in transient cycles
to avoid ammonia slippage. Mixing uniformity of urea and exhaust. The particulate (SOF and carbon)
reduction in modern SCR systems (up to 74% demonstrated) with no trapping function.
17.30
End of day five and course