An Overview of Combustion Concepts and Research Directions for Compression Ignition Engines Martin H. University of Oxford, UK FPC2015 Future Powertrain Conference National Motorcycle Museum, Solihull 25th 26th February 2015
JLR Centre of Excellence for Combustion in Compression Ignition Engines JLR/Oxford University partnership providing targeted research on near and medium-term technologies Lab within a lab Secure experimental facilities Dedicated research staff Core programme extended by studentships Flexible research framework to meet industry needs
Table of Contents 1 Background 2 Combustion mode 3 LTC 4 New Technologies 5 Conclusions
Outline Background Combustion mode LTC New Technologies Conclusions In the News Demonising the Diesel Significant high-profile debate Global climate concerns vs local air quality Real world vs drive cycle emissions 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 and Bae, 1988 Computer generated contour map describing soot and NOx production in equivalence ratio temperature space adapted from Dec [2009]
Φ-T Space Diesel Combustion Characteristics Conventional Operation Multiple ignition sites Ignition in fuel-rich low temperature zones Stoichiometric high-temperature diffusion flame PM-NOx trade-off adapted from Dec [2009]
Φ-T Space Diesel Combustion Characteristics Low temperature region Near-zero NOx Near-zero PM No PM-NOx trade-off Q. How might LTC best be achieved in practice? adapted from Dec [2009]
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 Operating Conditions 1500 rpm 1.2 bar MAP Single injection 900 bar P inj 16 mg m fuel
PM-HC Emissions High EGR Mixing-Controlled LTC Operating Conditions 1500 rpm 1.2 bar MAP Single injection 900 bar P inj 16 mg m fuel
Advancing diesel LTC High EGR Mixing-Controlled LTC Reducing the amount of fuel that escapes combustion (or is partially 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 CO emissions 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 as part 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: substantially different 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
The need for fundamental science Reinventing the CI Combustion Process (2) Fuel spray, ignition and combustion events are being placed into new pressure and temperature regimes As a result, existing numerical models either Do not incorporate the required physics (the physics may not be well known or understood), or Have not been validated under the conditions of interest Significant fundamental research is required to further the advancement of new combustion technologies Key areas: Spray and combustion modelling, fuel design (tailored fuels), instrumentation (optical diagnostics)
The need for fundamental science Laser Induced Thermal Grating Spectroscopy (LITGS) Novel temperature diagnostic developed in Oxford Physics (led by Prof. Paul Ewart) Portable device under development Fibre delivered beams possible
Conclusions Future emissions standards can be met by combination of in-cylinder control and aftertreatment cost challenge The relative complexity of diesel engine combustion is both a challenge and an opportunity New combustion regimes under development offer the potential of reducing the aftertreatment burden Realising this potential will require new investment in fundamental combustion research