Engines and Fuels - nfpahub.com · • Thermal efficiency is defined as: • It ranges from zero at...
Transcript of Engines and Fuels - nfpahub.com · • Thermal efficiency is defined as: • It ranges from zero at...
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
while meeting ever tighter emission standards
20142015
20162017
20182019
20202021
2022
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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
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
Review of current engine types
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
ignition delay, mixing time• Early LTC• Late LTC
Conventional Combustion Diesel LTC
High Oxygen Content Charge AirLow Oxygen/High EGR Charge AirLiquid FuelFirst-Stage IgnitionSoot & Soot Precursors
NOx Soot Hydrocarbons
From: Numerical and Experimental Studies of HCCI combustion, Salvador Aceves,
et al., Sixth Diesel Engine Emissions Reduction Workshop August, 2000.
Spark ignition compared to homogeneous
charge compression ignition (HCCI)
• Homogeneous charge, like SI
• Compression ignition, like diesel
• Ignition controlled by chemical kinetics– No propagating flame
– Multiple ignition sites
– Very fast combustion and high rate of pressure rise
Partially premixed Diesel LTC
LTC lowers soot and NOx but increases HC and CO
Lucachick, Glenn, Aaron Avenido, David Kittelson, and William Northrop, 2014. Exploration of Semi-Volatile Particulate Matter
Emissions from Low Temperature Combustion in a Light-Duty Diesel Engine, SAE paper number 2014-01-1306.
Reaction controlled compression
ignition, RCCI, using hydrous ethanol• Ethanol in US currently
anhydrous (>99% EtOH)
• Can save production energy up
to 30% with 150 proof EtOH
• Goal: Expand the market for
ethanol into diesel engines
• Hydrous ethanol has
advantages for diesel engines
when in dual fuel modes
– No PM and NOx aftertreatment
– Reduced need for EGR
– Increase fuel renewability
Fang, Wei, David B. Kittelson, William F. Northrop, and Junhua Fang, 2013.
An Experimental Investigation of Reactivity-Controlled Compression Ignition
Combustion in a Single-Cylinder Diesel Engine Using Hydrous Ethanol,
Proceedings of the ASME Internal Combustion Engine Division 2013 Fall
Technical Conference, ICEF2013.
Emissions benefits of dual-fuel RCCI• Data taken: single cylinder
research engine
– Isuzu medium duty
– Engine parameters controlled
• 80% fumigant energy fraction
• 150 proof hydrous EtOH
• Results:
– Meets Tier 4 NOx/soot, engine out
– Same power range as diesel-only
– Complete control of engine required (OEM solution)
• RSM analysis underway to minimize emissions and fuel consumption
• Aftermarket development underway
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
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
One projection by CARB of what will be
necessary to reduce passenger car CO2
emissions in California by 80% in 2050
In 2035 we will still as many vehicles
relying on engines as today
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
Heavy-duty engine efficiency targets and
achievements, DOE Supertruck
Oscar Delgado and Nic Lutsey, The U.S. Supertruck Program, ICCT White Paper June 2014
The long term goal is BTE > 55%
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
Future fuels will be judged on
carbon intensity
Source: California's Low Carbon Fuel Standard Final Regulation Order, April
15, 2010 www.arb.ca.gov/regact/2009/lcfs09/lcfscombofinal.pdf
Future fuels will be judged on
carbon intensity
Source: California's Low Carbon Fuel Standard Final Regulation Order, April
15, 2010 www.arb.ca.gov/regact/2009/lcfs09/lcfscombofinal.pdf
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
Conclusions
• Transportation engines are the main user of liquid petroleum fuels
• Both gasoline and diesel engines / vehicles are making large gains in efficiency– Projected substantial reduction in gasoline consumption
– Diesel consumption flat due to increasing worldwide use of diesel engines, especially heavy-duty
• Sharp decreases in emissions have been achieved but challenges remain– NOx
– Cold start
– Old vehicles
• Future fuels should be judged on their carbon footprints
Thank you, questions?
Additional materials
NOx emissions from buses in
real-world operation• The work reported here is part of a wider program on performance,
emissions, and fuel economy of modern transit buses
• Real world NOx emissions– Many current reports of real drive emissions exceeding certification standards
• Due to large differences between certification test cycles and real-world driving
• Sadly, in some cases, due to cheating, cycle beating by the manufacturer – not the case in this work!
– This program has primarily focused on 2013 technology urban buses
– 2013 engine MY buses met lab certification but • Emitted well above certification levels under real-world driving conditions
• But complied with Not to Exceed Standards, perfectly legal!– Highly transient real-world cycle
– Never in NTE window long enough for exceedance
– Cummins has an ongoing program to improve real world emissions and has recalibrated 2015 bus engines
– Metro transit bought 120 2015 Cummins powered buses
– We evaluated NOx emission from a randomly selected 2015 MY bus from Metro Transit fleet
Test buses
2013 MY
1503 - Standard Diesel
2013 MY
7290 - Series Hybrid
2013 MY
7327 - Parallel Hybrid
2015 MY
1713 - Standard Diesel
Bus Manufacturer
LayoutGILLIG Low Floor New Flyer XcelsiorTM GILLIG Hybrid GILLIG Low Floor
Engine Cummins ISL 8.9L Cummins ISB 6.7L Cummins ISB 6.7L Cummins ISL 8.9L
Transmission ZF-EcolifeTM BAE HybriDriveTM Allison Electric DrivesTM ZF-EcolifeTM
Emissions 2013 Certified SCR and DPF2015 Certified SCR and
DPF
AC Compressor Thermoking Belt DrivenThermoking 3-Phase
ElectricThermoking Belt Driven Thermoking Belt Driven
Power SteeringMechanical Engine
Coupled
230VAC 3-Phase
Electric
Mechanical Engine
Coupled
Mechanical Engine
Coupled
Engine Fans EMP - 28VDC Electric 8 or 9 Fan
Air CompressorMechanical Engine
Coupled
230VAC 3-Phase
Electric
Mechanical Engine
Coupled
Mechanical Engine
Coupled
On-road Evaluation Of Energy Flows And Emissions From New Technology
Conventional And Hybrid Transit Buses, Andrew Kotz, William Northrop and
David Kittelson , 26th CRC REAL WORLD EMISSIONS WORKSHOP
Newport Beach, California, March 13-16, 2016
Test routes selected – normal
passenger serviceLow Speed Route
• Speed: 17mph
• KI: 2.4 s-1
Mid Speed Route
• Speed: 25mph
• KI: 1.5 s-1
High Speed Route
• Speed: 28mph
• KI: 0.6 s-1
𝐾𝐼 =𝐶ℎ𝑎𝑟𝑎𝑐𝑡𝑒𝑟𝑖𝑠𝑡𝑖𝑐 𝐴𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛
𝐴𝑒𝑟𝑜𝑑𝑦𝑛𝑎𝑚𝑖𝑐 𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦
On-road Evaluation Of Energy Flows And Emissions From New Technology
Conventional And Hybrid Transit Buses, Andrew Kotz, William Northrop and
David Kittelson , 26th CRC REAL WORLD EMISSIONS WORKSHOP
Newport Beach, California, March 13-16, 2016
Test Matrix – wide range of
conditions
Summer
13Winter 14 Spring 14
Summer
14
Summer
15Winter 16
Min. Temperature 58 ºF -17 ºF 39 ºF 42 ºF 58 ºF 6 ºF
Max.
Temperature90 ºF 38 ºF 78 ºF 91 ºF 90 ºF 46 ºF
Avg. Temperature 71 ºF 10 ºF 56 ºF 71 ºF 77 ºF 26 ºF
Good Test Days 9 19 13 16 9 9
Start Date 8/5/2013 1/13/2014 5/5/2014 7/14/2014 8/9/2015 2/8/2016
End Date 8/20/2013 2/13/2014 5/20/2014 8/14/2014 9/5/2015 2/20/2016
2015-16 test
program testing 1503
and 1713
2013-14 test program testing 1503, 7290,
7337: conventional, series hybrid , parallel
hybrid
On-road Evaluation Of Energy Flows And Emissions From New Technology
Conventional And Hybrid Transit Buses, Andrew Kotz, William Northrop and
David Kittelson , 26th CRC REAL WORLD EMISSIONS WORKSHOP
Newport Beach, California, March 13-16, 2016
Very low real-world NOX emissions
from 2013 retro and 2015 buses
• New study operation over 10 days:– 2013 MY – 258 Hours
– 2015 MY – 260 Hours
– 1.8*106 Data Entries
On-road Evaluation Of Energy Flows And Emissions From New Technology
Conventional And Hybrid Transit Buses, Andrew Kotz, William Northrop and
David Kittelson , 26th CRC REAL WORLD EMISSIONS WORKSHOP
Newport Beach, California, March 13-16, 2016
Real-world operating
conditions compared to FTP
*Kotz, A. J.; Kittelson, D. B.; Northrop, W. F. Lagrangian Hotspots of In-Use NOx Emissions
from Transit Buses. Environ. Sci. Technol. 2016 DOI: 10.1021/acs.est.6b00550.
FTP certification cycle far from bus operating conditions
Particle Emissions from Gasoline
Spark Ignition Engines (SI)
• Why do gasoline engines produce less PM that diesel? Simply stated combustion is much more premixed
• Two major classes of gasoline SI engines– Port fuel injection, PFI
• Until recently the most common design
• Stoichiometric operation, 3-way catalyst
• Low particle emissions except during cold start and high load
• Small, semi-volatile particles under cruise conditions
– Gasoline direct injection GDI, DISI• Better fuel economy than PFI
• Mainly stoichiometric operation, 3-way catalyst
• Particle emissions intermediate between PFI and Diesel
• Low semi-volatile fraction
• Lean burn, better fuel economy but higher PM and PN emissions
• Likely to need filters to meet PN
Passenger car particle standards,
mass, number, size
Trend line based on Maricq, 2010, shaded areas based on data from
Giechaskiel, et al., 2012
Passenger car particle standards,
mass, number, size
Will filters be
needed?
Trend line based on Maricq, 2010, shaded areas based on data from
Giechaskiel, et al., 2012