Engines and Fuels: Prof. David Kittelson, Department of Mechanical ...

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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0.04

0.06

0.08

0.1

0.12

0.14

Fle

et

Avera

ge N

Ox +

NM

OG

(g

/mi)

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

Outline







• 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







• 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







• 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

Outline







• 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





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





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





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

Engines and Fuels: Prof. David Kittelson, Department of Mechanical ...

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