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Center for Diesel Research
Potential of Modern Internal Combustion Engines – Review of
Recent trendsDavid Kittelson
Center for Diesel Research Department of Mechanical Engineering
University of Minnesota
February 15, 2011
Center for Diesel Research
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
Center for Diesel Research
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
Center for Diesel Research
Thermal efficiency of modern engines
• Thermal efficiency is defined as:
• 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
InputFuelEnergyWorkOuputiciencyThermalEff =
Center for Diesel Research
2009
Source: Annual Energy Outlook 2011, U.S. Energy Information Administration
Transportation constitutes 28% of U.S. energy consumption 94% of it comes from petroleum – 74% of petroleum use
More than 50% of this is imported
Center for Diesel Research
0
4
8
12
16
1995 2000 2005 2010 2015 2020 2025 2030 2035
Most transport fuel growth is in light and heavy duty vehicles
U.S. transportation energy consumptionmillion barrels per day oil equivalent
Rail
Air
ProjectionsHistory
Heavy-duty vehicles
Light-duty vehicles
Marine
2009
4%
67%
2%
10%
16%
64%
20%
9%4%2%
Source: Annual Energy Outlook 2011, U.S. Energy Information Administration
Center for Diesel Research
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/
Center for Diesel Research
Historical fleet CO2 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/
Center for Diesel Research
We need to meet the challenge of increased efficiency while meeting ever tighter emission standards
2014 2015 2016 2017 2018 2019 2020 2021 2022
S1
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
Flee
t Ave
rage
NO
x +
NM
OG
(g/m
i)Model Year
Proposed CA light-duty vehicle emission standards
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
Center for Diesel Research
Quick review of current engine types
Source: Diesel Power: Clean Vehicles for the Future - https://www1.eere.energy.gov/informationcenter/
Center for Diesel Research
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.
Center for Diesel ResearchFrom: Numerical and Experimental Studies of HCCI combustion, Salvador Aceves, et al., Sixth Diesel Engine Emissions Reduction Workshop August, 2000.
Center for Diesel Research
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
1000 1400 1800 2200 2600 3000Temperature (K)
SI Region
LTC Region
6
5
4
3
2
1
Typical Diesel Droplet Combustion Path
Kitamura et al (2002)
Φ
Center for Diesel Research
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
Center for Diesel Research
GM gasoline engine improvement plans
Source: Advanced Propulsion Technology Strategy, Tom Stephens, 2010 DOE DEER Conference
Center for Diesel Research
GM Diesel engine improvement plans
Source: Advanced Propulsion Technology Strategy, Tom Stephens, 2010 DOE DEER Conference
Center for Diesel Research
VW engine improvement plans
Source: Future Directions in Engines and Fuels, Stuart Johnson, 2010 DOE DEER Conference
Center for Diesel Research
Cummins heavy-duty Diesel engine improvement plans
Source: High Efficient Clean Combustion for SuperTruck, Donald Stanton, USDOE DEER 2009 conference
Center for Diesel Research
Cummins is exploring organic Rankine bottoming cycles
Source: Exhaust Energy Recovery, Chris Nelson, USDOE DEER 2009 conference
Center for Diesel Research
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 turbo-
supercharging – 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.
Center for Diesel Research
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
Center for Diesel Research
Predicted trends in U.S. passenger car consumption
Source: L. Cheah,J.Heywood/EnergyPolicy39(2011)454–466
By 2030 hybrid gasoline electric vehicles will consume roughly 1/3 the fuel of a current conventional vehicle
Center for Diesel Research
One projection by CARB of what will be necessary to reduce passenger car CO2 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
Center for Diesel Research
Cummins projected heavy-duty engine efficiencies
Source: High Efficient Clean Combustion for SuperTruck, Donald Stanton, USDOE DEER 2010 conference
Center for Diesel Research
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
Center for Diesel Research
Engine combustion – direction – Lund University, Sweden
Source: Path to High Efficiency Gasoline Engine, Bengt Johansson, 2010 DOE DEER Conference
Center for Diesel Research
Scania D13 running on diesel and gasoline
Source: Path to High Efficiency Gasoline Engine, Bengt Johansson, 2010 DOE DEER Conference
Operating a Diesel engine with very early injection timing and low octane gasoline allows it to operate in a LTC mode
Center for Diesel Research
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
Center for Diesel Research
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
Center for Diesel Research
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).ft3.MPG
Source: L. Cheah,J.Heywood/EnergyPolicy39(2011)454–466
Center for Diesel Research
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)
Center for Diesel Research
Questions?
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