Potential of Modern Internal Combustion Engines Review of Recent trends

Potential of Modern Internal Combustion Engines Review of Recent trends David Kittelson Department of Mechanical Engineering University of Minnesota February 15, 2011

Outline Background Current engine types Fuel economy standards Emission standards New combustion modes Trends in new engine design Projected engine and vehicle performance trends Fundamental research programs Conclusions

Thermal efficiency of modern engines Thermal efficiency is defined as: ThermalEff iciency = WorkOuput FuelEnergyInput It ranges from zero at idle to a maximum value at high load and moderate speed Spark ignition gasoline engine with 3-way catalyst ~ up to mid 30% range Passenger car Diesel ~ up low 40% range Heavy-duty truck Diesel ~ up to high 40% range Large (very) marine Diesel like that shown on right ~ 50% DOE target heavy-duty SuperTruck goal 55% Stringent emission standards must be met

Transportation constitutes 28% of U.S. energy consumption 94% of it comes from petroleum 74% of petroleum use 2009 More than 50% of this is imported Source: Annual Energy Outlook 2011, U.S. Energy Information Administration

Most transport fuel growth is in light and heavy duty vehicles U.S. transportation energy consumption million barrels per day oil equivalent History 2009 16 Projections 12 8 67% Light-duty vehicles 64% 4 0 16% 10% 4% 2% Heavy-duty vehicles Air Marine 1995 2000 2005 2010 2015 2020 2025 2030 2035 Rail 20% 9% 4% 2% Source: Annual Energy Outlook 2011, U.S. Energy Information Administration

Historical fleet fuel economy performance and current or proposed standards Source: Global Comparison of Light-Duty Vehicle Fuel Economy/GHG Emissions Standards - http://www.theicct.org/passenger-vehicles/global-pv-standards-update/

Historical fleet CO 2 emissions performance and current or proposed standards Source: Global Comparison of Light-Duty Vehicle Fuel Economy/GHG Emissions Standards - http://www.theicct.org/passenger-vehicles/global-pv-standards-update/

We need to meet the challenge of increased efficiency while meeting ever tighter emission standards 0.14 Fleet Average NOx + NMOG (g/mi) 0.12 0.1 0.08 0.06 0.04 0.02 Proposed CA light-duty vehicle emission standards 0 2014 2015 2016 2017 2018 Model Year 2019 2020 2021 2022 S1 Heavy-Duty Light-Duty Source: Heavy Duty Diesels The Road Ahead, Elmar Boeckenhoff, US DOE DEER conference 2010 Source:http://www.arb.ca.gov/msprog/levprog/leviii/meetings/111610 /draft_sftp2_regs_nov2010.pdf

Quick review of current engine types Source: Diesel Power: Clean Vehicles for the Future - https://www1.eere.energy.gov/informationcenter/

A new direction in engines Low temperature combustion Diesel Diffusion burning of fuel jet High efficiency High compression ratio Lean combustion Very high combustion efficiency > 99% No throttle Low hydrocarbon and CO emissions Soot and NOx must be controlled by expensive exhaust aftertreament Diesel particle filter NOx control by SCR or lean NOx trap Fuel economy penalty Spark ignition Usually premixed Moderate efficiency Moderate compression ratio to avoid knock Chemically correct combustion Poor light load efficiency due to throttling Moderate combustion efficiency ~ 90% High hydrocarbon, CO, and NOx emissions, low soot emissions Hydrocarbon, CO, and NOx emissions easily controlled by relatively inexpensive 3-way catalyst How do we get the high efficiency of a Diesel engine without high NOx and soot emissions that require expensive exhaust aftertreament? A new combustion mode low temperature combustion (LTC) There are many flavors of LTC including, for example, homogeneous charge compression ignition (HCCI), partially premixed combustion (PPC), reaction controlled compression ignition (RCCI) and alphabet soup.

From: Numerical and Experimental Studies of HCCI combustion, Salvador Aceves, et al., Sixth Diesel Engine Emissions Reduction Workshop August, 2000.

Diesel, spark ignition, and LTC follow different paths during combustion Diesel Fuel rich region initially surrounds each droplet as fuel evaporates At roughly φ = 3-4 diffusion burning starts Mixing path passes through soot formation and NOx formation regions Spark ignition Premixed combustion take place at near φ = 1 Very high NOx, CO and HC HCCI Premixed conditions avoid both soot and NOx islands However bulk and wall quenching lead to high CO and HC emissions Φ 6 5 4 3 2 1 Typical Diesel Droplet Combustion Path LTC Region 1000 1400 1800 2200 2600 3000 Temperature (K) Kitamura et al (2002) SI Region

GM gasoline engine improvement plans Source: Advanced Propulsion Technology Strategy, Tom Stephens, 2010 DOE DEER Conference

GM Diesel engine improvement plans Source: Advanced Propulsion Technology Strategy, Tom Stephens, 2010 DOE DEER Conference

VW engine improvement plans Source: Future Directions in Engines and Fuels, Stuart Johnson, 2010 DOE DEER Conference

Cummins heavy-duty Diesel engine improvement plans Source: High Efficient Clean Combustion for SuperTruck, Donald Stanton, USDOE DEER 2009 conference

Cummins is exploring organic Rankine bottoming cycles Source: Exhaust Energy Recovery, Chris Nelson, USDOE DEER 2009 conference

Diesel and spark ignition engines are on converging paths toward LTC Spark Ignition Direct injection Turbo-supercharging Downsizing Variable valve lift and timing Displacement management Adaptive control with advanced sensors Reduced friction LTC modes, HCCI, PCCI, etc. Diesel Higher levels of turbosupercharging two stage Even higher injection pressure, multiple injections Variable valve timing Adaptive control with advanced sensors Reduced friction Advanced aftertreatment Downsizing Waste heat recovery Turbocompound Organic Rankine Thermoelectric LTC modes, HCCI, PCCI, etc.

Predicted trends in U.S. passenger car consumption By 2030 hybrid gasoline electric vehicles will consume roughly 1/3 the fuel of a current conventional vehicle Source: L. Cheah,J.Heywood/EnergyPolicy39(2011)454 466

One projection by CARB of what will be necessary to reduce passenger car CO 2 emissions in California by 80% in 2050 In 2040 we will still as many vehicles relying on engines as today Source: The Path to Low Carbon Passenger Vehicles, Tom Cackette, USDOE DEER 2010 conference

Cummins projected heavy-duty engine efficiencies Source: High Efficient Clean Combustion for SuperTruck, Donald Stanton, USDOE DEER 2010 conference

Engine combustion direction Lund University, Sweden Source: Path to High Efficiency Gasoline Engine, Bengt Johansson, 2010 DOE DEER Conference

Scania D13 running on diesel and gasoline Operating a Diesel engine with very early injection timing and low octane gasoline allows it to operate in a LTC mode Source: Path to High Efficiency Gasoline Engine, Bengt Johansson, 2010 DOE DEER Conference

Conclusions Engines promise to be around for many years The need to reduce consumption while producing near zero emissions has spurred innovation Diesel and spark ignition engines are on a converging path, low temperature combustion modes are likely for both engine types By 2030 gasoline electric hybrid vehicles are projected to deliver roughly three times the fuel economy of today s conventional gasoline vehicles Thermal efficiencies will continue to increase Approaching 50% for light-duty engines Approaching 60% for heavy-duty engines

Is there a quicker path to high mileage? Today s engine and driveline in a vehicle with 1985 acceleration and size would get 39 MPG, a 56% improvement! PSFI = P.S.F.I = (hp/lb). ft 3. MPG Source: L. Cheah,J.Heywood/EnergyPolicy39(2011)454 466

Ongoing research Low temperature combustion of producer gas (DOE, IREE, DOD) From a biomass gasifier From a catalytic reformer Dimethyl ether, a second generation renewable diesel fuel (IREE, GM) Life cycle GHG and economic analysis Performance and emission measurement Fuel handling and injection system development Development of an integrated powertrain research facility (NSF) Development of combined diesel particle filter and lean NOx trap (Dow Chemical) Solid particle measurement systems (AVL) Miniature free piston HCCI engine compressor (CCEFP-NSF)

Questions?