NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Advanced Combustion 

and Fuels

P.I.: Bradley T. Zigler

National Renewable Energy Laboratory

2014 Annual Merit Review

Washington, D.C.

June 19, 2014

NREL/PR-5400-61893 Project ID # FT002

This presentation does not contain any proprietary, confidential, or otherwise restricted information.
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Overview

Project Start Date: October 2013

Project End Date: September 2014

Percent Complete: 66%

Program funded one year at a time

From DOE/VTO 2011 – 2015 MultiYear Program Plan

• Inadequate data and predictive 

tools for fuel property effects on 

combustion and engine 

efficiency optimization (Fuels & 

Lubricants Technologies)

• Lack of modeling capability for 

combustion and emission 

control (Advanced Combustion Engine 

R&D)

• Inadequate data on long-term 

impact of fuel and lubricants on 

engines and emission control 

systems (Fuels & Lubricants Technologies)

Funding Received in FY13: $822K

Funding for FY14: $697K

Timeline

Budget

Barriers

• Colorado School of Mines (CSM)

• 15 industry, 6 univ., and 6 nat’l lab 

partners via Advanced Engine 

Combustion (AEC) – Memorandum of 

Understanding (MOU) 

• Project Lead: National Renewable

Energy Laboratory (NREL)

Partners
3

Relevance

• Develop experimental techniques to address data voids for ignition 

performance where other methods are challenged:

o Low volatility fuels

o Surrogate fuel blends

o Prototype compounds where only small quantities (<30 mL) are available 

o Lubricating oil / fuel mixtures (to address low speed pre-ignition [LSPI])

• Provide feedback and validation of kinetic mechanisms through coupled 

simulation of experiments 

• Conduct complementary engine-based studies focusing on quantifying fuel 

physicochemical effects not fully captured by other means (octane number)

Objective: Address technical barriers of inadequate data and 

 predictive tools for fuel and lubricant effects on

 advanced combustion engines.

NREL 23595

Credit: Dennis Schroeder / NREL 
4

Milestones

Month / 

Year

Milestone or 

Go/No-Go Decision

Description Status

Aug 2013 Milestone Submit draft journal article 

documenting expanded results of 

validating ignition kinetic models 

with ignition quality tester (IQT) 

simulation and experimental data.

Completed

Dec 2013 Milestone Deliverable – Project status 

summary to DOE Prog. Mgr.

Completed

Mar 2014 Milestone Deliverable – Project status 

summary to DOE Prog. Mgr.

Completed

Jun 2014 Milestone Deliverable – Project status 

summary to DOE Prog. Mgr.

On schedule

Sep 2014 Milestone Deliverable – Project status 

summary to DOE Prog. Mgr.

On schedule
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Approach/Strategy

• Address technical barriers of inadequate data and predictive tools for fuel 

effects, including biofuels, on advanced combustion engines.

• Collaborate with other laboratories, universities, and industry to develop 

accurate, computationally efficient kinetic mechanisms and models necessary 

for coupled computational fluid dynamics (CFD) simulation.

• Develop unique capability to experimentally test and validate simulations for 

ignition performance of compounds, blends, and surrogates at engine-relevant 

conditions, addressing data voids and complementing other methods.

• Adapt tools to study novel problems, like lubricant impacts on LSPI.

• Share information through publication, direct collaboration, and forums like 

the AEC – MOU.

• Contribute to the “portfolio” of tools and technologies necessary to diversify 

fuels and increase engine efficiency, reducing petroleum use.

Through collaboration, develop techniques, tools, and data to 

quantify critical fuel chemistry effects to enable development 

of advanced combustion engines that use alternative fuels.
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Past Technical Accomplishments and Progress

DCN

IQT has been developed as a research tool to:

• Determine derived cetane number (DCN) given very limited volumes (~25 mL) of 

new fuel components or complex blends for early-stage fuel screening feedback.
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Past Technical Accomplishments and Progress

DCN 8-point parametric studies

IQT has been developed as a research tool to:

• Determine derived cetane number (DCN) given very limited volumes (~25 mL) of 

new fuel components or complex blends for early-stage fuel screening feedback.

• Determine Arrhenius parameters given small volumes for initial simulation work.
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Past Technical Accomplishments and Progress

DCN 8-point parametric studies

Temperature sweeps

IQT has been developed as a research tool to:

• Determine derived cetane number (DCN) given very limited volumes (~25 mL) of 

new fuel components or complex blends for early-stage fuel screening feedback.

• Determine Arrhenius parameters given small volumes for initial simulation work.

• Complement rapid compression machine (RCM) and shock tube data voids.
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Past Technical Accomplishments and Progress

DCN 8-point parametric studies

Temperature sweeps

Simulation

IQT has been developed as a research tool to:

• Determine derived cetane number (DCN) given very limited volumes (~25 mL) of 

new fuel components or complex blends for early-stage fuel screening feedback.

• Determine Arrhenius parameters given small volumes for initial simulation work.

• Complement rapid compression machine (RCM) and shock tube data voids.

• Provide valuable data / feedback loop to assist kinetic mechanism development.
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Technical Accomplishments and Progress

C16H34 – diesel blending surrogate

Other devices can work over a limited range 

with decane (volatile enough for shock tubes 

and RCMs)

... but not hexadecane yet (low volatility)

C10H22 – gasoline blending 

surrogate C12H26 – kerosene range surrogate

NREL significantly expanded temperature sweep studies beyond C7 isomers to C10

– C16 ranges, yielding unique ignition data for gasoline, jet fuel, and diesel-range 

surrogates. These data are critical to validating reduced kinetic mechanisms. 
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Technical Accomplishments and Progress

NREL data cover NTC region

G. E. Bogin, E. Osecky, M. A. Ratcliff, J. Luecke, X. He, B. T. Zigler, and A. M. Dean, “An Ignition 

Quality Tester (IQT) Investigation of the Negative Temperature Coefficient Region of Alkane 

Autoignition," Energy Fuels, 2013, 27 (3), pp 1632–1642

NREL studied 2,2,4,4,6,8,8-heptamethylnonane (iso-cetane, or HMN, C16H34) in detail:

• HMN defines the low end of the cetane scale (DCN = 15).

• It pushed our capability to span long ignition delay times, bridging to gasolinerange fuel studies.

• Few experimental data exist, all at higher temperatures, outside of critical 

negative temperature coefficient (NTC) region.

• HMN is a key surrogate and included in the CRC AVFL-18 diesel surrogate blend.

• Validation of Lawrence Livermore National Lab (LLNL) HMN mechanism needed.
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Technical Accomplishments and Progress

Initial mechanism updates have reduced 

discrepancy in NTC region down from an 

order of magnitude error

• NREL / CSM identified a discrepancy between IQT experiments and simulation in 

the critical NTC region with LLNL’s HMN mechanism.

• Based on NREL’s NTC region data and CSM / NREL’s initial modifications (of 

thermodynamic data and certain radical reactions) to the LLNL HMN mechanism, 

LLNL, CSM, and NREL are now collaborating to update the mechanism.

• LLNL and CSM are co-revising mechanism rate rules and key radical reactions, 

with NREL IQT data.

• NREL will test new mechanism with simulations against experimental data.

• This will be the first time IQT experiments and simulation data are used in a 

feedback development loop to improve a kinetic mechanism.
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Technical Accomplishments and Progress

• LSPI limits gasoline direct injection (GDI) engine efficiency; may be due to 

interaction of fuel and lube oil in crevice volume area.

• IQT-based experiments now reach GDI engine conditions and are used to study 

compounded ignition effects of gasoline range fuels + lubricants.

• Work with industry will transition from surrogates to suspected compounds.

• This research supports development of lubricants to enable increased GDI engine 

efficiency.

Gasoline surrogate, Research 

octane number (RON) = 100

Gasoline surrogate, ~ Anti-Knock 

Index (AKI) = 87

Diesel surrogate, RON = 0

Gasoline surrogates doped 

with icosane (C20H42) or 

2-ethylhexyl nitrate 

(C8H17ONO3) ignition 

accelerants

640°C 400°C
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• Study of impacts of highly knock-resistant fuel blends on GDI engines.

• GDI efficiency gain potential with high-octane biofuel blends, including separation 

of evaporative cooling effect vs. chemical octane effect (building on prior AVL / 

Ford research).

• Engine has been modified to add an upstream fuel injector along with the direct 

injector to separate chemical octane number effect from evaporative cooling 

effect, which is not fully captured in RON or motor octane number 

measurements. 

• Single-cylinder research engine is based on GM 2.0L “LNF” engine, similar to ones 

at Oak Ridge National Lab (ORNL) and Argonne National Lab (ANL).

• Various biofuels will be studied, including trimethylbenzene, ethanol, isobutanol, 

2-phenyl ethanol, and dimethyl furan.

• Experiments are underway.

NREL 23595

Credit: Dennis Schroeder / NREL 

NREL 22767

Credit: Dennis Schroeder / NREL 

Technical Accomplishments and Progress
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Responses to Previous Year Reviewers’ Comments

“The reviewer observed a strong systematic 

approach for improving the accuracy of the ignition 

delay model for biofuels.” – We continue to build 

this capability, and are investigating methods to 

provide ignition feedback at a much earlier stage in 

biofuel development using microliter samples.

“The reviewer noted interesting results, but that 

the project has not directly shown the results for 

tackling ... inadequate predictive tools for fuel 

property effects on engine efficiency optimization.” 

– We feel the recent work to update the HMN 

mechanism is an example where our work helps 

others, such as LLNL, develop improved CFD tools 

that engine OEMs use to improve efficiency.

“The reviewer commented that the data support simulation and predictive 

capabilities for engine design by providing validation of chemical kinetics 

mechanisms.” – We continue to expand the IQT-based capability while being 

cautious about the bounds where our data still have significant basis for ignition 

kinetics studies vs. being too influenced by spray physical processes.
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Collaboration and Coordination with Other Institutions

• Colorado School of Mines

o Sponsorship of Prof. Greg Bogin’s joint appointment at NREL

o Sponsorship of Eric Osecky’s Ph.D. thesis research

o Support of Stephanie Villano and Prof. Tony Dean’s ab initio kinetic mechanism development

• University of California–Berkeley

o Collaboration with Prof. J. Y. Chen on IQT-based simulation, experiments, and validation of 

reduced hexadecane mechanism

o Collaboration with Hunter Mack and Tim Sennott with IQT data for prototype advanced biofuels 

and data for molecular structure-based predictions

• Lawrence Livermore National Laboratory

o Collaboration with Bill Pitz, Charlie Westbrook, and Marco Mehl on C7 alkane isomers, alkenes, 

HMN, and other important surrogate compounds

• Argonne National Laboratory

o Collaboration with Sibendu Som on experiments and simulation with ANL’s three-component soy 

biodiesel surrogate

• Coordinating Research Council

o Co-development of advanced diesel surrogates with accurate compositional, ignition-quality, and 

volatility characteristics (AVFL-19 project, see Mueller, Project # FT004)

o Includes three industry partners and six U.S. and Canadian national laboratories

• Advanced Engine Combustion – MOU

o Ten engine OEMs

o Five energy companies

o Six DOE national laboratories

o Six DOE-funded universities also participate by invitation (through 2013)
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Remaining Challenges and Barriers

• Fuel and lubes ignition studies

• The IQT “ignition delay” incorporates both spray physics and ignition 

kinetics. It has been a challenge to operate in regimes where the physical 

delay fraction is only a small portion of the ignition delay time. This bounds 

experimental space where IQT data are of value. A new fuel injection 

system (or other device) may help.

• How can we provide DCN screening feedback with even smaller quantities 

so this can be part of a transformative feedback loop to biofuel process 

development?

• The initial IQT-based LSPI studies are encouraging, but establishing cause / 

effect with suspected compounds and closing the loop with engine studies 

will be difficult.

• Single-cylinder GDI engine studies on advanced biofuels

• The studies underway must complement past AVL / Ford work on ethanol as 

well as ORNL studies, but expand to other advanced biofuels.

• Can we provide enough guidance for potential efficiency gains with spark 

timing sweeps with the current production compression ratio? 
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Proposed Future Work (FY14)

• Continue fuel and lubes ignition studies

o Provide additional data and feedback for key compounds to refine kinetic 

mechanisms and mechanism reductions.

o Complete HMN mechanism development feedback loop with LLNL and 

CSM.

o Continue to provide DCN screening given small (~ 25 mL) samples of 

compounds.

o Transition lubricants LSPI (“superknock”) research from surrogates to 

suspected compounds, with industry collaboration.

• Continue single-cylinder GDI engine studies on advanced biofuels

o Build on knowledge gained for key compounds from Bob McCormick’s 

Advanced Biofuels research area.

o Coordinate research with ORNL to ensure projects are complementary. 

o Continue focus on physicochemical effects that may be leveraged to 

increase efficiency.

o Identify and quantify effects not captured with current methods, 

specifically due to heat of vaporization.
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Proposed Future Work (FY15 and beyond)

• Expand fuel and lubes ignition studies

• Provide additional data and feedback for key compounds to refine kinetic 

mechanisms and mechanism reductions, focusing on experimental data.

• Correlate data between IQT, shock tubes, and rapid compression machines to 

strengthen value for CFD / reduced mechanism development.

• Continue to provide DCN screening given small (~ 25 mL) samples of 

compounds.

• Develop capability to measure relevant ignition properties of novel 

compounds with extremely small samples (on the μL scale).

• Use IQT as a tool to provide guidance for lubricant formulations to suppress 

LSPI.

• Expand single-cylinder GDI engine studies on advanced biofuels

• Continue focus on physicochemical effects that may be leveraged to increase 

efficiency with experiments to complement ORNL research.

• Increase static compression ratio of engine based on piston design shared 

from ORNL.

• Identify and quantify effects not captured with current methods, supporting 

long-term development of new fuels / characterization to enable increased 

engine efficiency.
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Summary

• Guidance from past AMRs and other forums (AEC – MOU) has improved 

quality and guided focus for this research activity.

• IQT-based research now involves several collaborations to address data 

voids, provide feedback for mechanism development, and develop 

surrogates.

• Engine-based research coordinates with that in industry and in other DOE 

labs, with focus on fuel effects vs. engine combustion process development

Objective: Address technical barriers of inadequate data and 

 predictive tools for fuel and lubricant effects on

 advanced combustion engines.

Through collaboration, develop techniques, tools, and data to 

quantify critical fuel chemistry effects to enable development 

of advanced combustion engines that use alternative fuels.
Technical Back-Up Slides
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Methyl 9-decenoate

Methyl decanoate

n-Heptane

2 bar

0.25 mol

0.25 mol

0.5 mol

Technical Accomplishments and Progress

NREL collaborated with ANL to experimentally map ignition performance 

of a soy biodiesel blend surrogate ANL co-developed. NREL is also 

assisting with simulation to compare against experimental data.