the future of the internal combustion...

ORNL is managed by UT-Battelle, LLC for the US Department of Energy

The Future of the Internal Combustion EngineRoles & Responsibilities

Robert M. Wagner

Scott Curran

National Transportation Research Center

Oak Ridge National Laboratory

https://www.ornl.gov/ntrc

2ISEF 2018 Tianjin | International Summit of Breakout Technology of Engines and Fuels

Acknowledgements

Mr. Gurpreet Singh, Mr. Kevin Stork, and Dr. Mike Weismiller

of the United States Department of Energy Vehicle

Technologies Office

The United States Department of Energy Co-Optima

Initiative which is led by the Vehicle Technologies Office

and the Bioenergy Technologies Office(https://www.energy.gov/eere/bioenergy/co-optimization-fuels-engines)

Dr. Scott Curran and my colleagues at the National Transportation

Research Center at Oak Ridge National Laboratory(https://www.ornl.gov/ntrc)

https://www.energy.gov/eere/bioenergy/co-optimization-fuels-engines

https://www.ornl.gov/ntrc


Two decades of fuel-economy performance Faster, cleaner, safer, and more efficient

Source: “The Race to Improve Fuel Economy”, Consumer Reports, February 22, 2018 (Link)

https://www.consumerreports.org/fuel-economy-efficiency/the-race-to-improve-fuel-economy/#performance


Improvements due to breakthroughs spanning fundamentals and systems

Fundamentals Engine System Vehicle System

Fuel economy, drive-cycle emissions, and cost

Breakthroughs in transient

control, transmissions, hybridization, onboard

computing, etc.

Vehicle Power Demand

Time

Source | Ricardo

Brake (shaft) efficiency and emissions

Breakthroughs in air-handling, thermal management, emissions

controls, materials, etc.

Indicated efficiency and emissions

Breakthroughs in sprays, combustion, cyclic dispersion,

catalysis, simulation, etc.


Advances in engine technologies are enabling the transition from fundamentals to vehicle system

• Fast manipulation of

engine conditions

• Precision fuel delivery

• Flexible valve timing

• ….

Advanced controls

More Flexible Components

• In-cylinder pressure

• Fast emissions

• In-line torque

Fast measurements

Improved Sensors

Powertrain Electrification

• Reduced speed-load

requirements

• Reduced transients

• Stored electrical energy

• ….

Hybrid Propulsion

• Artificial intelligence

• Data interpretation

• Simulation

• Pattern recognition

• Prediction

Rapid analysis

Increased Onboard Computing Power


Peak engine efficiency continues to improve

“The maximum BTE expected for slider-crank engines is about 60%, assuming that cost is not a constraint.”

Source: https://info.ornl.gov/sites/publications/Files/Pub26829.pdfSource: Toshihiro Hirai, Nissan, “Strategic Future: Powertrain Vision for Tomorrow”,

Internationales Wiener Motorensymposium 2017


Opportunity is more than peak brake thermal efficiency

Source: Adapted from presentation by Mr. Tom

McCarthy, Ford Motor Company, 2017 SAE

International Range Extender Symposium


Solutions needed across entire range – strong opportunity for part-load

Source: Graphic Adapted from Tom McCarthy, 2017 SAE REx Symposium

Current

Peak BTE Island

Expanded

high BTE

island

How far can

we go?

Engine Speed

Load

Load

Load


Challenges with the transients and edge cases


Fundamental and system improvements driving overall higher vehicle

tractive efficiency

Source: Pannone, Novation Analytics, Thomas ORNL, “Decomposing Fuel Economy

and Greenhouse Gas Regulatory Standards…”, SAE 2017-01-0897


New vehicle architectures are changing the role of the internal combustion engine

Leads to different application and design requirements for internal combustion engines


Directly coupledConventional Transmission

Partially decoupledParallel Hybrid

Partially decoupledPowersplit Hybrid

Completely decoupledSeries Hybrid

Increased flexibility in decoupling engine operation from vehicle power demands


Source: Adapted from presentation by Mr. Tom

McCarthy, Ford Motor Company, 2017 SAE

International Range Extender Symposium


Engine combustion opportunities


Advanced Compression IgnitionSpark Ignition

New opportunities with potential to blend the best of conventional

Low Reactivity Fuel High Reactivity FuelRange of Fuel Properties TBD(depends on combustion mode)

Mixing Controlled Cl


Incomplete Combustion

ACI / Low Temperature Combustion

Diesel Combustion

SI

Source: Combustion movies courtesy of Dr. Mark

Musculus at Sandia National Laboratories


ACI blends the best characteristics of diesel and SI combustion – high efficiency with low emissions

Figure Source: Dr. Jim Szybist, ORNL

• Success or failure of ACI will be

driven by the ability to navigate

engine operational space

• Use of ACI may require a

multimode approach due

to many challenges

– Stability and controllability

– Limited speed/load range

– High combustion noise

– High HC and CO emissions

– Lower exhaust temperatures

and emissions controls


ACI blends the best characteristics of diesel and SI combustion – high efficiency with low emissions

Low Load Bound

CO, unburned HC,

combustion stability

High Load Bound

Noise, peak pressure

rise rate, NOx emissions

ACI

Boosted SI

*Note: ACI efficiency contour is notional and does not represent real data

Figure Source: Dr. Jim Szybist, ORNL

• Success or failure of ACI will be

driven by the ability to navigate

engine operational space

• Use of ACI may require a

multimode approach due

to many challenges

– Stability and controllability

– Limited speed/load range

– High combustion noise

– High HC and CO emissions

– Lower exhaust temperatures

and emissions controls


ACI is a continuum – observation is useful for exploring load expansion

Reference: http://jer.sagepub.com/content/early/2016/01/14/1468087415621805.full.pdf+html

-360 -300 -240 -180 -120 -60 0

HCCI Partial Fuel Stratification

Moderate Fuel Stratification

Heavy Fuel Stratification

Full Fuel Stratification

Level of In-Cylinder Fuel Stratification at the Start of Combustion

http://jer.sagepub.com/content/early/2016/01/14/1468087415621805.full.pdf+html


Fuel/air stratification and fuel properties drives reactivity stratification

Source: Adapted from Klos, D., Janecek, D., and Kokjohn, S., SAE 2015-01-0841.

Gasoline

Diesel

This is for a fixed temperature. Local temperature has strong

impact on ignition delay and will shift these curves.

Equivalence Ratio(isosurface at 2.0)

Local Temperature(isosurface at 2000k)


Example fuel/air stratification control

-360 -300 -240 -180 -120 -60 0

Partial Fuel Stratification


INTAKE COMPRESSION

COMBUSTION

EXHAUST

Benefits

Low NOx and soot emissions

Challenges

Limited range, high HCs and CO,

often unstable

Benefits

High combustion efficiency, wide

operational range, controllable

Challenges

High NOx and soot emissions

Increase fuel stratification to improve stability and emissions

Increase ignition delay to improve emissions

while maintaining controllability

“Stratified enough”

to quote Gautam Kalghatgi


Moderate Fuel Stratification


Partial Fuel Stratification

CA50 CA50 CA50

CA05 CA05 CA05

Transitioning from Low Temperature Combustion to non-LTC

2323

• Emissions – Very low NOx and soot emissions

• Controllability – Predominately premixed leads to stability issues

• Takeaways – Limited operating range, fuel chemistry must be “phi-sensitive” to

provide controllability benefit with small levels of stratification

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HCCIPartial Fuel

StratificationModerate Fuel Stratification


Full Stratification

CA05 CA50

INTAKE COMPRESSIONEXHAUSTCOMBUSTION

2424

-360 -300 -240 -180 -120 -60 0

CA05 CA50


• Emissions – Very low NOx and soot emissions

• Controllability – Predominately premixed leads to stability issues

• Takeaways – Limited operating range, fuel chemistry must be “phi-sensitive” to

provide controllability benefit with small levels of stratification

HCCIPartial Fuel



Full Stratification

2525

-360 -300 -240 -180 -120 -60 0

HCCIPartial Fuel



Full Stratification

• Emissions – Higher NOx emissions, lower soot

• Controllability – Late injection serves as ignition source to control the combustion timing and

elongate the burn duration (reducing the pressure rise rate)

• Takeaways – Strategy has potential for wide LTC operating range with conventional gasoline,

but benefits from other fuel properties as well

CA05 CA50


2626

-360 -300 -240 -180 -120 -60 0

HCCIPartial Fuel



Full Stratification

• Emissions – Potential for low soot emissions, but requires high EGR for low NOx emissions

• Controllability – Excellent through use of injection timing to control ignition

• Takeaways – Very wide operating range, challenges with combustion noise and

air/dilution control required for low NOx emissions

CA05 CA50



Multi-fuel Opportunities


Multi-fuel expands reactivity stratification potential

Single-fuel approach dependent on injection strategy to drive stratification

Multi-fuel approach has added dimension of fuel properties to control reactivity stratification

Gasoline-like

Variable fuel properties between gasoline and diesel


How much reactivity ∆ is enough?

Single fuel

Zero ∆ Fuel Reactivity

Gasoline

Variable fuel properties between gasoline and diesel

High ∆ Fuel Reactivity

GasolineDiesel

Example with PRF80 and PRF100

Low ∆ Fuel Reactivity (?)

Two fuels TBD – several options

• Octane membrane

• Onboard reformation

• Low- and premium-grade

gasoline

• Low volume additive

• Others?


Multi-mode examples


ORNL LTC/diesel multi-mode | MCCI used for speed/load demands outside of LTC range

• Objective to maximize fuel economy and minimize mode-switching

• Fuel properties (reactivity, HOV, etc.) shift or expand LTC operating range within

constraints (pressure rise rate, combustion efficiency, etc.)

Diesel / Gasoline

LTC operational space

with conventional fuels

20% Biodiesel Blend / Gasoline

Expanded low and high load

due to higher PFI to DI ratio

Diesel / 30% Ethanol Blend

Expanded high load and range shift due

to higher octane and charge cooling,

reduced low load due to stability issues

MCCI

LTC


ORNL LTC multi-mode operational range has significant impact on modeled fuel economy

0

10

20

30

40

50

60

70

UDDS HWFET US06

Fue

l Eco

no

my*

(m

pg) 1.6L GDI

gasoline

CIDI diesel

E30 RCCI

B20 RCCI

LTC Drive Cycle

Coverage

(non-idling)

B20/UTG ULSD/E30

UDDS 72% 52%

HWFET 88% 74%

* Fuel economy estimates based on experimental engine map and vehicle simulation


GM research on LTC multi-mode combustion to maximize efficiency

Source | DOE Annual Merit Review, https://www.energy.gov/eere/vehicles/downloads/vehicle-technologies-office-merit-review-2018-high-specific-output-gasoline

1/3

Torq

ue

[Nm

]

Speed [rpm]

https://www.energy.gov/eere/vehicles/downloads/vehicle-technologies-office-merit-review-2018-high-specific-output-gasoline




Torq

ue

[Nm

]

Speed [rpm]

2/3





Torq

ue

[Nm

]

Speed [rpm]

3/3



Mazda is introducing an advanced compression ignition engine

Gasoline EngineSpark-Ignition

SKYACTIV-XSpark Controlled

Compression Ignition

Source | Adapted from http://www2.mazda.com/en/next-generation/technology/

14.8% mpg increase vs Mazda 3 SKY-G - 35.1mpg vs. 29.9mpg

Source | SAE Magazine - http://articles.sae.org/15622/

http://articles.sae.org/15622/


Almost there …


Takeaways

• The role of engines is changing – our perspective and approach must

change with it

• Unprecedented improvements in engine technologies are enabling

high efficiency, improved performance, and reduced emissions

• Co-optimization of fuels and engines will further enable new

combustion modes

• Multi-mode operation has the potential for a major improvement in

vehicle fuel economy with reduced emissions

Engines are not done, there is more opportunity, and science is getting us there


Final thoughts

Fundamental breakthroughs in engines and

emissions controls, new materials, and

advanced manufacturing are enabling

cleaner and more efficient engines

Faster computers, deep learning, and unprecedented

diagnostics are accelerating knowledge discovery,

the design process, and calibration

ORNL Summit 200 PF system (left)

on path to exascale computing;

ORNL neutron diagnostics (below)

of a fuel injector and sprays

Engines must be approached as a dynamic

system in a system-of-systems to ensure

maximum fuel economy

Source | National Renewable Energy Laboratory

Thank you for your attention!

Robert Wagner | [email protected]

mailto:[email protected]

the future of the internal combustion...

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