Engines and Fuels Prof. David Kittelson TE Murphy Engine Research Laboratory Department of Mechanical Engineering University of Minnesota 2016 Fluid Power Innovation and Research Conference October 10-12, 2016 Hyatt Regency Hotel Minneapolis, Minnesota
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Engines and Fuels
Prof. David Kittelson
TE Murphy Engine Research Laboratory
Department of Mechanical Engineering
University of Minnesota
2016 Fluid Power Innovation and Research Conference
October 10-12, 2016
Hyatt Regency Hotel
Minneapolis, Minnesota
Outline
• Background– Energy use patterns
– Fuel economy and GHG standards
– Emission standards
• Trends in new engine design
• Projected engine and vehicle performance trends
• Carbon footprint of some alternative fuels
• Conclusions
Thermal efficiency of modern
engines• Thermal efficiency is defined as:
• It ranges from zero at idle to a maximum value at high load an 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
InputFuelEnergy
WorkOuputiciencyThermalEff
• Thermal efficiency should not be confused with combustion efficiency, the fraction of fuel burned to CO2, water. Often
– Typically greater than 90% spark ignition engines
– Often greater than 99% diesel engines
Transportation constitutes 28% of U.S. energy use 92%
from petroleum which is 72% of petroleum use
U.S. Energy Information Administration, Monthly Energy Review (April 2016),
Worldwide trends in fuel
economy standards
CO2 emissions fall as fuel
economy increases
Gasoline consumption is expected to fall while
diesel use is flat, sharp decrease in imports
We need to meet the challenge of increased efficiency
Source: Diesel Power: Clean Vehicles for the Future - https://www1.eere.energy.gov/informationcenter/
Review of current engine types
Source: Diesel Power: Clean Vehicles for the Future - https://www1.eere.energy.gov/informationcenter/
High efficiency, long life
High cost, complex aftertreament
lower efficiency, shorter life
lower cost, simple aftertreament
Diesel and spark ignition engines, nearly
parallel paths – advanced combustion
• Spark Ignition– Direct injection
– Turbo-supercharging
– Downsizing
– Variable valve lift and timing
– Displacement management
– Adaptive control with advanced sensors
– Reduced friction
– Advanced cycles, Atkinson, Miller
– LTC modes, HCCI, PCCI, etc.
• Diesel– Higher levels of turbo-
supercharging – two stage
– High 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.
A new direction in engines – Low
Temperature Combustion (LTC)• 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.
Low Temperature Combustion
• Alternative modes of engine
combustion
• LTC, HCCI, PCCI…etc
• Advantages:
• Low soot and NOx emissions
• Reduced heat loss = higher
efficiency
• Offers opportunity to reduce
need for emissions
aftertreatment
Diesel LTC
• High Cooled EGR Rates• Increased Fuel Injection Pressure• Modified Injection Timing to increase