Whither Diesel? An Overview of Combustion …...Combustion Concepts and Research Directions for Compression Ignition Engines Martin H. Davy University of Oxford, UK FPC2015 Future

Outline Background Combustion mode LTC New Technologies Conclusions

Whither Diesel? An Overview ofCombustion Concepts and Research

Directions for Compression Ignition Engines

Martin H. Davy

University of Oxford, UK

FPC2015 Future Powertrain ConferenceNational Motorcycle Museum, Solihull

25th–26th February 2015

Whither Diesel? Davy


JLR Centre of Excellence for Combustion inCompression Ignition Engines

JLR/Oxford University partnership providing targeted research onnear and medium-term technologies

• ‘Lab within a lab’

• Secure experimental facilities

• Dedicated research staff

• Core programme extended bystudentships

Flexible research framework to meet industry needs



Table of Contents

1 Background

2 Combustion mode

3 LTC

4 New Technologies

5 Conclusions



In the News

Demonising the Diesel

• Significant high-profiledebate

• Global climate concerns vslocal air quality

• Real world vs drive cycleemissions

High NOx levels in urban areas are particular focus of concern



Diesel Emissions

Historical Development of European Regulations

Black = CI, Red = PI



Diesel Emissions

Emissions Control for Conventional Diesel Operation

Aftertreatment is highly effective but complex and costly



Diesel Emissions

The Cost of Compliance

Estimated system costs of meeting selected emissions standards for a 2L engine, Data: ICCT 2012



Φ-T Space

Diesel Combustion Characteristics

The ‘Φ-T’ Map

• Due to Kamimoto andBae, 1988

• Computer generatedcontour map describingsoot and NOxproduction inequivalence ratio –temperature space

adapted from Dec [2009]



Φ-T Space


Conventional Operation

• Multiple ignition sites

• Ignition in fuel-rich lowtemperature zones

• Stoichiometrichigh-temperaturediffusion flame

• PM-NOx trade-off




Φ-T Space


Low temperature region

• Near-zero NOx

• Near-zero PM

• No PM-NOx trade-off

Q. How might LTC bestbe achieved in practice?




Strategies for Low Temperature Combustion

Some of the Many ‘Flavours’ of LTC

See also PCI, PPCI, RCCI,...



PM-NOx Emissions

High EGR ’Mixing-Controlled” LTC

OperatingConditions

• 1500 rpm

• 1.2 bar MAP

• Single injection

• 900 bar Pinj

• 16 mg mfuel



PM-HC Emissions


OperatingConditions

• 1500 rpm

• 1.2 bar MAP

• Single injection

• 900 bar Pinj

• 16 mg mfuel



Advancing diesel LTC


Reducing the amount of fuel that escapes combustion (or ispartially oxidized) in MC-LTC is the key issue for the technology.

Improvements in this area would:

• Increase efficiency

• Reduce emissions and fuel consumption

• Extend load range

Advances in fundamental understanding of HC and COemissions sources in diesel LTC are urgently required



Advancing diesel LTC

Enabling Technologies for ”Mixing-Controlled” LTC

• LTC specific combustion systems

• LTC specific FIE and fuel injection strategies

• Advanced T/C technologies

• Low-temperature light-off oxycats

Potential benefits

• Substantially reduced aftertreatment burden



The Automotive Council Roadmap

The Internal Combustion Engine in 2040?



Pushing the boundaries

Ultra Efficient Engines and Fuels



Pushing the boundaries

Split-Cycle Engines

Concept under investigation by Brighton University and Ricardo aspart of ”Ultra” Project

Recuperated Split Cycle. Fig: courtesy of Dr. R. Morgan (Brighton University)



The need for fundamental science

Reinventing the CI Combustion Process (1)

Common theme of new CI combustion concepts: substantiallydifferent in-cylinder conditions c.f. conventional diesel operation

These may include:

• Very high levels of EGR (poor availability of oxygen)

• Greatly increased peak pressures and temperatures

• Supercritical conditions at start of fuel injection

• Greatly increased levels of turbulence

Further:

• Greatly increased fuel pressures and levels of boost




Reinventing the CI Combustion Process (2)

Fuel spray, ignition and combustion events are being placed intonew pressure and temperature regimes

As a result, existing numerical models either

• Do not incorporate the required physics (the physics may not bewell known or understood), or

• Have not been validated under the conditions of interest

Significant fundamental research is required to further theadvancement of new combustion technologiesKey areas: Spray and combustion modelling, fuel design (tailored fuels),instrumentation (optical diagnostics)




Laser Induced Thermal Grating Spectroscopy(LITGS)

Novel temperature diagnostic developed in Oxford Physics (led byProf. Paul Ewart)

Portable device under developmentFibre delivered beams possible



Conclusions

• Future emissions standards can be met by combination ofin-cylinder control and aftertreatment – cost challenge

• The relative complexity of diesel engine combustion is both achallenge and an opportunity

• New combustion regimes under development offer thepotential of reducing the aftertreatment burden

• Realising this potential will require new investment infundamental combustion research


Documents

Whither Diesel? An Overview of Combustion …...Combustion Concepts and Research Directions for Compression Ignition Engines Martin H. Davy University of Oxford, UK FPC2015 Future