A Strong Energy Portfolio for a Strong America 

Energy efficiency and clean, renewable energy will mean a stronger economy, a cleaner environment, 

and greater energy independence for America. Working with a wide array of state, community, industry, and 

university partners, the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy 

invests in a diverse portfolio of energy technologies.

For more information contact:

EERE Information Center

1-877-EERE-INF (1-877-337-3463)

www.eere.energy.gov
U.S. Department of Energy 

1000 Independence Avenue, S.W. 

Washington, D.C. 20585-0121 

FY 2005 

Progress Report for Fuels Technologies 

Energy Efficiency and Renewable Energy 

Office of FreedomCAR and Vehicle Technologies 

Approved by Stephen Goguen 

January 2006 

Fuels Technologies FY 2005 Progress Report 

Contents

I Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

II Fuels and Lubricants to Enable High Efficiency Engine Operation while 

Meeting 2007 - 2010 Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

II.1 Development of a Passenger Car Test Platform to Evaluate NOx 

Adsorber/DPF Systems Using Ultra-Low Sulfur Fuels – National Renewable 

Energy Laboratory.........................................................................................................................17

II.2 Development of a Pick-up/SUV Test Platform to Evaluate NOx 

Adsorber/DPF Systems Using Ultra-Low Sulfur Fuels – National Renewable 

Energy Laboratory.........................................................................................................................24

II.3 Fuel-Borne and Fuel-Derived Reductants for Diesel Exhaust NOx Reduction 

– Oak Ridge National Laboratory.................................................................................................31

II.4 Effectiveness and Sulfur Tolerance of Selective Catalytic Reduction and Diesel Particle

Filter Systems – Oak Ridge National Laboratory.........................................................................35

II.5 Phosphorus Poisoning of Diesel Oxidation Catalysts – Oak Ridge National Laboratory ............39

II.6 Rapid Aging of Lean NOx Traps (LNTs) – Oak Ridge National Laboratory ..............................44

II.7 Ultra-Low Sulfur Reduction Emission Control Device – Honeywell Laboratories .....................50

II.8 Fuel and Emission Control System Effects on Unregulated Emissions – Oak Ridge 

National Laboratory......................................................................................................................55

II.9 Testing at the ReFUEL Laboratory – National Renewable Energy Laboratory...........................59

III Fuel Property Effects on Advanced Combustion Regimes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63

III.1 Using Non-Traditional Diesel Fuels and Optical Diagnostics to Understand and 

Optimize In-Cylinder Processes – Sandia National Laboratories ................................................65

III.2 Chemical Kinetic Modeling of Combustion of Automotive Fuels 

– Sandia National Laboratories ....................................................................................................72

III.3 Improving Ethanol Life Cycle Energy Efficiency by Direct Combustion of Wet Ethanol 

in HCCI Engines – Lawrence Livermore National Laboratory ....................................................76

III.4 Fuels for Diesel HCCI Engines – National Renewable Energy Laboratory .................................81

III.5 Fuel Effects on Gasoline-Based HCCI Performance and Emissions – Oak Ridge 

National Laboratory......................................................................................................................85

III.6 Fuel Effects on Diesel-Based Advanced Combustion Regimes 

– Oak Ridge National Laboratory.................................................................................................90

III.7 Fuel Effects on Diesel-Based HCCI Performance and Emissions 

– Oak Ridge National Laboratory.................................................................................................94

IV Transition to Hydrogen Economy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97

IV.1 Advancing Gaseous Fuel Vehicle and Infrastructure Technology – National Renewable 

Energy Laboratory.........................................................................................................................99

IV.2 Recovery of Natural Gas from Renewable Resources – Brookhaven National Laboratory.......104

iii 
Fuels Technologies FY 2005 Progress Report 

V Petroleum Displacement Fuels/Fuel Blending Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

V.1 Operability Results of Class 6 Vehicles Operating on GTL Fuel with Catalyzed DPFs 

– National Renewable Energy Laboratory ..................................................................................111

V.2 Biodiesel Quality and Stability – National Renewable Energy Laboratory................................114

V.3 Resolving Barriers and Showing Incentives for Non-Petroleum Fuels in Near-Term 

Uses – Oil Sands Fuels Characterization – Oak Ridge National Laboratory .............................119

VI New Technology Impacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

VI.1 Weekend Ozone Effect Studies – National Renewable Energy Laboratory ...............................127

VII Abstracts of Newly Awarded Projects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

VII.1 Natural Gas Vehicle Cylinder Safety, Training and Inspection 

– Clean Vehicle Education Foundation .......................................................................................133

VII.2 Natural Gas Vehicle Roadmap and Data Collection Effort – Clean Vehicle 

Education Foundation .................................................................................................................134

VII.3 Investigation of Bio-Diesel Fueled Engines under Low-Temperature 

Combustion Strategies – University of Illinois............................................................................135

VIII Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

IX Author Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

iv 
Fuels Technologies FY 2005 Progress Report 

I Introduction

1
Fuels Technologies FY 2005 Progress Report 

2
Fuels Technologies FY 2005 Progress Report 

I Introduction

Advanced Petroleum-Based, Non-Petroleum-Based, and Renewable Fuels for a Clean and 

Secure Highway Transportation System 

On behalf of the Department of Energy’s Office of FreedomCAR and Vehicle Technologies (FCVT), 

we are pleased to introduce the Fiscal Year (FY) 2005 Progress Report for Fuels Technologies. The potential 

benefits of advanced fuels technologies include: 

• Energy security: Advanced fuels enable more efficient engines that reduce fuel use, and non-petroleumbased fuels reduce the demand for petroleum fuel, much of which is imported. 

• Environmental sustainability: Cleaner fuels enable efficient and durable emissions control technologies 

for reduced vehicle emissions. Advanced and non-petroleum-based fuels reduce the emissions of 

greenhouse gases. 

• Economic improvement: A more diverse portfolio of fuels in transportation will improve the economy 

by reducing price volatility and stimulating new market activity in areas such as renewable fuels. 

The Fuels Technologies Sub-Program is an integral part of the FreedomCAR government/industry 

partnership and a key component to achieving the FreedomCAR mission to develop more energy-efficient and 

environmentally friendly highway transportation technologies that enable America to use less petroleum in 

transportation. The work in advanced petroleum-based fuels is conducted through joint programs with the 

energy and automotive industries and utilizes the expertise of National Laboratories and universities. 

Advanced petroleum-based fuels are even more important to the 21st Century Truck Initiative that proposes to 

dramatically increase heavy-duty vehicle fuel economy while continuing to reduce emissions. For heavy 

over-the-road trucks, combustion engines operating on liquid fuels are the only viable options in the 

foreseeable future for these vehicles given our current transportation fuels distribution infrastructure. 

The Fuels Technologies Sub-Program works closely with the Advanced Combustion Engine R&D 

Sub-Program of FCVT, which is focused on removing critical technical barriers to commercialization of higher 

efficiency, advanced internal combustion engines in light-duty, medium-duty, and heavy-duty vehicles. Fuels 

Technologies Sub-Program activities are also coordinated with appropriate DOE/industry technical teams; 

the light-duty automotive, heavy-duty engine, and energy industries; and federal, state, and local government 

agencies. Some activities are undertaken in coordination with the Biomass Program, the Hydrogen, Fuel Cells 

and Infrastructure Technologies Program, and the Office of Fossil Energy via the Fuels Crosscut Team to 

ensure maximum synergy and to avoid duplication of effort. 

Goals 

• By 2007, identify fuel formulations optimized for use in 2007-2010 technology diesel engines that 

incorporate use of non-petroleum-based blending components with the potential to achieve at least 

a 5 percent replacement of petroleum fuels. 

• By 2010, identify fuel formulations optimized for use in advanced combustion engines (2010-2020) 

providing high efficiency and very low emissions, and validate that at least 5 percent replacement of 

petroleum fuels could be achieved in the following decade. 

3 
Shut-In U.S. Crude Production Due to Hurricanes in 2005 

Source: U.S. Energy Information Administration 

Fuels Technologies FY 2005 Progress Report 

Transportation Fuels and Energy Security 

Petroleum-derived fuels account for 

98% of all fuel used in the U.S. highway 

transportation sector. This sector includes 

private automobiles used for passenger 

transport and commercial trucks used for 

the transport of goods. Because of the lack 

of alternative sources of energy in this 

sector, a widespread disruption of petroleum 

supplies due to natural disaster, political 

maneuvering, or resource depletion has the 

potential to severely disrupt personal and 

commercial mobility in the U.S. This was 

vividly illustrated during the summer 

months of 2005 when several hurricanes hit 

the Gulf Coast of the U.S., disrupting at one 

point 28% of domestic crude oil production 

and 29% of U.S. refining capacity. These 

disruptions caused the price of crude oil to spike up to over $70/bbl and retail gasoline prices to reach over 

$3/gal over most of the U.S. Overall, crude oil and gasoline prices rose about 50% from the beginning of 2005 

to its end. The Energy Information Administration projects that crude oil and gasoline prices will stay at levels 

similar to those at the end of 2005 throughout most of 2006. 

Petroleum currently supplies about 40% of all the energy used in the U.S., with 67% of this petroleum 

going to the transportation sector. The transportation sector alone consumes more petroleum than is produced 

in the U.S.; 67% of the petroleum consumed in the U.S. is imported. By 2025, the U.S. is expected to import as 

much as 77% of its petroleum, and the Organization of Petroleum Exporting Countries (OPEC) will need to 

increase oil production by 80% to satisfy not only increasing demands for petroleum in the U.S., but in the rest 

of the world as well, where demand is growing even faster. Such heavy dependence on non-indigenous energy 

sources leaves the U.S. vulnerable to petroleum price spikes and shortages, as well as related consequences. 

Research sponsored by the Fuels Technologies Sub-Program focuses on tailoring petroleum-based fuels 

to accommodate and enable more efficient use, and on increasing use of renewable and non-petroleum-derived 

fuels. For example, oil-sand-derived fuels from Canada, Fischer-Tropsch fuels made from natural gas, and 

biofuels derived from fats and vegetable oils will play increasingly important roles as extenders to 

conventional diesel fuel. Approximately 40% of the crude oil produced in Canada is from oil sands and 

production of oil sands liquids is projected to grow significantly over the next several years. Since Canada is 

our largest supplier of crude oil and we import between 80 and 90% of their production, it is likely that oil 

sands liquids will represent an increasing portion of our transportation fuel. Likewise, in 2005, biodiesel 

production in the U.S. tripled from the 2004 level, and the number of plants planned to be built equals the 

number already in place. How the addition of these fuels impacts the physical and chemical characteristics 

of diesel fuel needs to be known to preserve and enhance the efficiency and emissions of advanced engines. 

Transportation Fuels and the Environment 

The combustion process used to convert the energy in petroleum fuels to propulsion for current highway 

vehicles creates criteria pollutants in large enough quantities to be detrimental to the environment and 

dangerous to human health, particularly in densely populated areas. Criteria pollutants include carbon 

monoxide, oxides of nitrogen (NOx), particulate matter, ammonia, volatile organic compounds (VOCs), and 

sulfur dioxide. These pollutants are blamed with forming ozone and smog, causing acid rain, and contributing 

to a number of health issues – especially respiratory problems. Highway vehicles are responsible for 51% of 

4 
Transportation is the Second Largest Source of Greenhouse 

Gases in the U.S. 

Source: U.S. Environmental Protection Agency 

Fuels Technologies FY 2005 Progress Report 

all carbon monoxide emissions in the U.S., according to the U.S. Environmental Protection Agency (EPA). 

These vehicles also contribute 34% of all NOx emitted and 29% of all VOCs emitted—these are the two 

components necessary for ozone formation. 

Combustion of petroleum fuels also 

releases greenhouse gases (primarily CO2) 

that are believed to contribute to global 

warming. Highway vehicles emit 1,460 

trillion grams of CO2 equivalent greenhouse 

gases per year in the U.S. Transportation 

greenhouse gases have increased at a rate of 

about 1.7% per year since 1990. Increases 

in the number of vehicles and the miles 

traveled per year are responsible for this 

increase, as well as a general decline in 

average light-duty vehicle fuel economy. 

In the short term only minor adjustments can 

generally be made through consumer 

behavior (e.g., not driving as far for summer 

vacation). However, long-term adjustments 

such as increased vehicle fuel economy (i.e., more efficient engines and powertrains) and non-petroleum 

renewable fuels are needed to reduce highway transportation’s contribution to greenhouse gas emissions. 

Emissions of harmful pollutants and greenhouse gases from combustion processes depend in large part on 

the conditions used in combustion and on fuel properties. The fuel property that has attracted the most 

attention due to its damaging effects on emission control devices is sulfur content. Through a rulemaking in 

2000, the EPA mandated that the sulfur content of highway diesel fuel be lowered to 15 ppm maximum by June 

2006 to enable emission controls to reduce oxides of nitrogen and particulate matter from diesel engines. 

Engineering data to support the need for diesel fuel sulfur reduction to less than 15 ppm was generated by a 

previous DOE-led program, DECSE (Diesel Emission Control Sulfur Effects), and referenced in the EPA 

rulemaking. Though the sulfur reduction mandate is still 6 months away (retailers will be allowed to sell diesel 

fuel having up to 22 ppm sulfur through October 15 as part of the transition), some energy companies have 

been supplying ultra-low sulfur diesel fuel in certain areas where air pollution is a large concern. 

In a separate rulemaking in early 2000, EPA required the amount of sulfur to be reduced in gasoline, down 

to a 30 ppm average by 2006, with a maximum cap of 80 ppm. Phase-in of this requirement began in 2004, but 

the final stage and largest change begins on January 1, 2006, as the sulfur level in gasoline is lowered from an 

average 300 ppm to a maximum average 30 ppm with the exception of some motor gasoline produced in the 

Rocky Mountain region. All motor gasoline must be in compliance by 2008. 

Removal of MTBE as a blending component from motor gasoline, another pending change, will likely 

increase gasoline prices and possibly lead to greater price volatility. State concerns about potential water 

contamination are driving efforts to eliminate MTBE as a gasoline additive. Some MTBE removed from the 

gasoline pool may be replaced by the renewable fuel ethanol, which continues to grow in supply. 

The Fuels Technologies Sub-Program is addressing sulfur reduction and mitigation strategies as well as 

other technologies to enable emission reductions. Fuel properties are being matched with combustion 

conditions and advanced combustion regimes to develop optimal systems with both high efficiencies and low 

emissions. Renewable and non-petroleum-based fuels are being pursued because they are generally sulfur-free 

and have desirable properties for lowering criteria emissions. Blends of renewable and non-petroleum fuels 

with petroleum fuels have much potential to decrease emissions and improve fuel properties in general. 

Renewable fuels have the added benefit of reduced greenhouse gas emissions. 

5 
Fuels Technologies FY 2005 Progress Report 

Transportation Fuels and the Economy 

Crude oil prices increased significantly over the past year, due primarily to strong worldwide demand, 

particularly in developing countries, but also from the disruption of U.S. crude oil production in the Gulf of 

Mexico due to hurricanes. As of late 2005, crude oil was about $67 per barrel, compared with $46 per barrel in 

December 2004. Crude oil spiked above $70 per barrel in 2005 based on concerns about economic and 

political stability in some oil producing countries, hurricane-induced production cut-backs, and concern that 

new discoveries were falling behind production. The value of petroleum products imported into the U.S. 

increased by 40% in 2005 compared to 2004, and represents about 31% of our entire trade deficit, up from 28% 

in 2004. While higher petroleum prices have not significantly affected the U.S. economy, their contribution to 

our growing trade deficit is worrisome. 

The potential economic benefits of implementing advanced vehicle and fuels technologies in the U.S. are 

many. Technologies that improve fuel economy will reduce the amount consumers spend on fuel, allowing 

consumers to spend more in other areas of the economy. Reduced fuel spending also translates to reduced 

imports, improving the trade deficit. Renewable fuels such as ethanol and biodiesel offer opportunities for 

expanding economic activity, especially in the agricultural sector; when used to replace or supplement 

petroleum fuels, they also improve the trade deficit. 

The Fuels Technologies Sub-Program is conducting research that will yield substantial benefits to the 

energy security of our country, to our environment, and to our economy. By cooperating with other DOE 

programs to leverage synergies, this Sub-Program greatly improves the prospects for advanced fuels and 

advanced vehicle technologies. 

Sub-Program Laboratory Capabilities 

The ReFUEL Lab at the National Renewable Energy Laboratory (NREL) is dedicated to future fuels and 

advanced heavy-duty vehicle research. It features a heavy-duty chassis dynamometer for vehicle performance 

and emissions research, an engine dynamometer test cell capable of certification-quality emissions testing, and 

a fuel chemistry laboratory for performing precise studies of fuel properties, including ignition quality. In FY 

2005, advanced facility capabilities, enhanced expertise, and new protocols were developed and utilized to lead 

and support fuels and heavy-duty hybrid vehicle research projects in support of DOE objectives and goals. 

Several test projects provided first-ever available data for new technologies and alternative fuels. 

At Sandia National Laboratory (SNL), the Fuels Research Laboratory is focused on developing a 

fundamental understanding of the combustion characteristics of advanced liquid petroleum-based, bio-derived, 

and synthetic fuels. Research is conducted using the Sandia Compression-ignition Optical Research Engine 

(SCORE), which is a single-cylinder version of a Caterpillar® C-10 engine that has been modified at Sandia to 

provide extensive optical access into the combustion chamber. Advanced laser and imaging diagnostic 

techniques are used to observe combustion and emissions-formation processes through windows in the piston 

and the upper periphery of the cylinder liner. Such observations are important for understanding how fuel 

formulation affects engine efficiency and emissions. In FY 2005, experiments conducted in the Fuels Research 

Laboratory showed for the first time how fuel and combustion-regime changes can enable diesel combustion 

that simultaneously achieves 1) NOx and soot emissions compliant with EPA limits that will come into force in 

2010, 2) uncompromised fuel economy, and 3) simpler combustion timing control and lower pressure-rise rates 

than those associated with homogeneous charge compression ignition (the prevailing advanced combustion 

approach to date). 

At Oak Ridge National Laboratory (ORNL), the Fuels, Engines, and Emissions Research Center (FEERC) 

is a comprehensive laboratory for internal combustion engine technology, specializing in research on paths to 

higher efficiency, emissions reduction, fuel effects, and emissions chemistry. The facility’s capabilities include 

6 
Fuels Technologies FY 2005 Progress Report 

spectroscopy labs, bench-top engine exhaust simulators, a range of engine dynamometer cells, and a vehicle 

chassis dynamometer. In this facility, ORNL has developed several new diagnostic and analytical methods that 

allow greater definition of fuel combustion species and their spatial and temporal resolution in the emission 

control system. Among the recently added capabilities are: 

• Second & third (non-proprietary) full-pass engine electronic control systems 

• Electrospray mass spectrometry and negative chemical ion mass spectrometry for specific exhaust 

compounds and unregulated emissions 

• “Gated bagger” for time-resolved emissions speciation 

• Engine cell (sixth) area for single-cylinder engine research 

• Engine models/codes (WAVE, etc.) 

• Methods for “road-side” emissions measurements 

• Variable compression ratio and variable valve actuation engines 

An extensive study of fuel property effects on both gasoline-based and diesel-based HCCI performance 

and emissions was completed. The results were published showing that the fuel properties could in fact expand 

or shrink the HCCI operating space in the case of gasoline fuels. For diesel-like fuels, the results show how the 

cool-flame reactions are prominent in fuels with high cetane number. To more globally facilitate research in 

this area, ORNL conceived a vision to initiate a comprehensive project on how fuel properties affect advanced 

combustion processes like HCCI, and teamed with NREL to move the project plans forward. The effort will 

begin with design of a research fuel matrix via a working group of experts in this field convened under the 

auspices of the Coordinating Research Council. The project has been named “FACE” (fuels for advanced 

combustion engines). 

Highlights of Significant FY 2005 Accomplishments 

Fuels and Lubricants to Enable Efficient Engine Operation While Meeting 2007 - 2010 Standards 

• In research of fuel sulfur effects on diesel emission 

control systems, 2200 hours of aging were 

completed using an advanced compression ignition 

direct injection (CIDI) passenger car engine 

equipped with a NOx adsorber catalyst and 

particulate filter. The testing showed that 

particulate emissions can be controlled over this 

time period to Tier 2 Bin 5 levels using a diesel 

particulate filter and 15 ppm sulfur fuel, while the 

NOx adsorber needs more work on durability and 

desulfation to meet emissions regulations. Similar 

testing over 2000 hours using an advanced CIDI 

engine sized for pickup trucks and SUVs using 

similar emission controls and the same fuels 

showed very similar results, i.e., Tier 2 Bin 5 

particulate emissions could be achieved but the 

corresponding NOx emission level could not, 

despite high effectiveness. (NREL, FEV Engine 

Technology, Southwest Research Institute) Light-Duty CIDI Test Engine Used in APBF-DEC Project 

(NREL, FEV Engine Technology) 

7 
Fuels Technologies

• A novel in-cylinder fuel injection strategy was 

found to produce H2 under net-lean engine 

operation at ORNL. A demonstration experiment 

revealed that highly accelerated hydrocarbon 

selective catalytic reduction (HC-SCR) catalyst 

light-off is possible using this technique. Future 

experiments will explore the capability of fuelderived H2 to promote catalytic NOx reduction. 

(ORNL) 

• Southwest Research Institute (SwRI) aged two 

heavy-duty engine emission control systems 

comprising urea-selective catalytic reduction 

(SCR) and diesel particulate filters for a total of 

6,000 hours each and retested them for emissions 

using 15-ppm sulfur fuel. The systems 

demonstrated that they could meet the 2010 

emissions levels for heavy-duty engines using 

fuels with sulfur levels in the 0-30 ppm range. 

This project is now complete. 

• ORNL studied the effect of phosphorous (derived 

from the zinc dialkyldithiophosphate additive in 

lube oil used for wear control) in diesel engine 

exhaust on oxidation catalyst, NOx adsorber, and 

catalyzed particulate filter poisoning. Phosphorus 

concentrations were found to be greatest at the 

catalyst surface, with a steep concentration gradient 

along the washcoat depth. Hydrocarbon and CO 

oxidation catalyst light-off temperatures increased 

between 50°C and 100°C, showing significant loss 

of performance from phosphorous contamination. 

• In studies of the mechanisms of sulfur poisoning of 

emission controls, ORNL established protocols for 

rapid thermal aging experiments of lean NOx traps 

(LNTs) for both bench-flow reactors and engine 

benches. Rapid thermal aging of LNTs at aging 

temperatures of 900 and 1000°C using the benchflow reactor was completed. The migration and 

accumulation of potassium at the interface of the 

washcoat and the cordierite substrate in aged 

high-temperature LNTs was observed as well as 

sintering of precious metal in all LNTs evaluated 

at high temperatures. 

• Honeywell developed a sulfur removal filter and 

successfully demonstrated continuous sulfur 

removal at the 1 gallon scale. A 10 gallon version 

was constructed for engine testing. Loss of fuel 

lubricity was identified, and various fuel lubricants 

were studied. 

 FY 2005 Progress Report 

ORNL Experimental Set-Up to Measure the Impact of 

Lubricating Oil Phosphorous on Catalyst Durability 

Electron Probe Microanalysis Images of 

Potassium Compounds Taken by ORNL 

(top: new; bottom: aged) 

8 
Fuels Technologies FY 2005 Progress Report 

• The Advanced Petroleum-Based Fuel – Diesel Emission Control (APBF-DEC) Toxics and Unregulated 

Emissions team completed unregulated emissions sampling and analysis for three APBF-DEC projects: 

the heavy-duty selective catalytic reduction (SCR) project, the pickup/SUV NOx adsorber catalyst project, 

and the light-duty NOx adsorber catalyst project. The studies showed that diesel particulate filters appear 

to do a good job of removing the heavier polycyclic aromatic hydrocarbons from the engine-out exhaust, 

even under rich regeneration conditions and extensive aging. Conversely, naphthalene and methyl 

naphthalene increase with the NOx adsorber system and aging. Because these are gas-phase compounds, 

they are less likely to be retained by the diesel particulate filter. 

• The ReFUEL Laboratory at NREL quantified and published the first known data on the performance 

impacts of biodiesel blends and synthetic GTL fuels on engines and vehicles equipped with advanced 

aftertreatment to meet 2007 requirements. 

Fuel Property Effects on Advanced Combustion Regimes 

• Using fuel changes (oxygenated fuel), SNL demonstrated a high-efficiency (>44% indicated efficiency), 

2010-emissions-compliant (<0.2 g/hp-hr NOx, <0.05 filter smoke number) combustion strategy where 

ignition timing is simply controlled by injection timing, and peak pressure-rise rates are lower than for 

conventional diesel combustion. 

• Lawrence Livermore National Laboratory (LLNL) completed models for chemical kinetics of combustion 

for two major fuel components, toluene and methyl cyclohexane, and for an oxygenated diesel fuel 

additive, dimethyl carbonate. 

• LLNL conducted an analysis of a homogeneous 

charge compression ignition (HCCI) engine 

system that can work on highly hydrated ethanol 

while delivering high efficiency and low 

emissions. They found that HCCI engines can use 

highly hydrated ethanol which is less costly and 

energy intensive to produce than the anhydrous 

ethanol currently used for fuel purposes. 

• NREL quantified ignition quality versus 

temperature using the Ignition Quality Tester 

(IQTTM) for a base fuel and a matrix of four 

paraffinic fuels representing 3 boiling ranges and 

3 derived cetane number levels. Very clean HCCI 

combustion was achieved using these fuels – 

brake-specific NOx emissions of 0.02 g/bhp-hr 

and undetectable levels of smoke for certain fuels and operating conditions. 

• ORNL and AVL determined that spark-augmented HCCI is a valid and useful mode of engine control, 

distinct from pure HCCI, and completed a set of parametric experiments to show the extent that gasolinebased fuel properties can further expand or shrink this multi-mode HCCI operating space. 

• ORNL showed that fuels from a variety of feedstocks (oil-sands, petroleum, and vegetable oil) do exhibit 

high-efficiency clean combustion (HECC) behavior at a similar range of engine output and speed as 

conventional petroleum fuels. It was also shown that fuel properties within the limited range studied do 

not significantly expand the load/speed operating regime for HECC and that there is a strong influence of 

fuel properties on both particulate and hydrocarbon emissions in HECC modes. 

• ORNL completed installation and conversion of a small diesel engine to HCCI combustion and conducted 

two fuel effects studies for diesel range fuels. HCCI performance was correlated to fuel chemistry and 

cetane values using commercial diesel fuels, blends of diesel secondary reference fuels, and biodiesel fuel. 

Net Energy Balance for Highly Hydrated Ethanol That 

Can Be Used in HCCI Engines 

9 
Map of Current Hydrogen Vehicle & Station 

Development Projects with Proposed ICTC Hydrogen 

Demonstration Projects Added 

Fuels Technologies FY 2005 Progress Report 

Transition to Hydrogen Economy 

• Cummins Westport Inc. completed development of a 

lean-burn 8.9L natural gas (NG) engine meeting 

EPA 2007 emissions standards for use in multiple 

vehicle platforms. 

• NREL continued projects to develop and/or integrate 

the following NG engines meeting EPA 2007 

emissions standards: 8.1L John Deere (John Deere 

Power Systems), 12L Mack/Volvo (Volvo 

Powertrain), and 15L Cummins (Westport 

Innovations). 

• NREL continued projects to develop 11L Mack/ 

Volvo (variable valve timing with Volvo Powertrain) 

and 8.9L Cummins Westport Inc. (with Cummins 

Westport) NG engines meeting EPA 2010 emissions 

standards. 

• NREL initiated a project to develop a NG 

stochiometric engine for transit buses that meets 

EPA 2010 emissions standards. 

• NREL published the final safety evaluation report of 

a NG home refueling appliance. 

• An evaluation of opportunities to integrate hydrogen 

into natural gas vehicle (NGV) fueling stations of 

the Interstate Clean Transportation Corridor (ICTC) 

was completed. 

• NREL held a Natural Gas Vehicle Technology Forum meeting in August 2005 and updated its Web site. 

• Brookhaven National Laboratory demonstrated the viability of producing liquefied natural gas (LNG) on a 

small scale from landfill gas. Ten thousand gallons of LNG was produced and used to power the trucks 

hauling refuse to the landfill. 

Petroleum Displacement Fuels/Fuel Blending Components 

• An operability analysis of six months of fleet fueling and maintenance records demonstrated that heavyduty fleet vehicles with diesel particulate filters using gas-to-liquid diesel fuel incur operational costs 

similar to those incurred using conventional diesel fuels (NREL). 

• NREL completed a nationwide assessment of biodiesel (B20) quality and stability and identified peroxide 

formation and low water interfacial tension as issues when blending biodiesel to form homogeneous 

mixtures. 

• NREL (ReFUEL) completed engine dynamometer testing of a modern 300 hp diesel engine, equipped with 

exhaust gas recirculation (EGR), variable geometry turbocharger (VGT), and high pressure common rail 

fuel injection with different B20 blends (20% biodiesel, 80% conventional diesel fuel). The study 

provided an evaluation of the emissions of a modern production engine with various B20 blends with 

biodiesel made from feedstocks including soy oil, yellow grease, canola oil, and beef tallow. 

• NREL (ReFUEL) evaluated the effect of biodiesel on a 2004 compliant engine retrofitted with a catalyzed 

diesel particulate filter (DPF). The study compared emissions with and without the DPF system installed 

on reference ULSD fuel and B20 over the EPA transient certification test cycle as well as evaluating DPF 

regeneration performance with biodiesel compared to ULSD fuel. 

10 
Fuels Technologies FY 2005 Progress Report 

• As part of a project to quantify the real-world operating costs and emissions impact of 20% biodiesel blend 

(B20), ReFUEL tested two MY 2000 in-use buses on B20 and conventional diesel fuel as a reference fuel. 

Use of the B20 fuel resulted in statistically significant reductions for all regulated emissions including 

nitrogen oxides (NOx), which were reduced by 4% on average, which is in contrast to many engine stand 

studies which have shown the NOx emissions to generally increase with biodiesel use. Testing also 

supports fleet study work being performed by NREL on the in-use performance and maintenance impacts 

of B20 use in the Boulder, Colorado transit bus fleet (NREL) 

• ORNL utilized blended oil sands fuel for operation of a light-duty diesel equipped with a NOx adsorber 

catalyst using in-cylinder regeneration modes and found it to have very similar performance to a 

conventional petroleum diesel fuel with 15 ppm sulfur. 

• ORNL developed a combination of electron impact and chemical ionization mass spectroscopic methods 

for identification of fuel components from oil sands crude. 

New Technology Impacts 

• NREL completed analysis of 1998-2002 or 2003 ambient ozone precursor and ozone data from many U.S. 

monitoring locations. A paper was submitted summarizing study results to the Journal of the Air & Waste 

Management Association for peer review and subsequent publication. 

Future Activities 

This section describes the activities that will be pursued in each portion of the Fuels Technologies 

Sub-Program in the next year. 

Fuels and Lubricants to Enable Efficient Engine Operation While Meeting 2007 - 2010 Standards 

Activities in the coming year in this portion of the Fuels Technologies Sub-Program will focus on how fuel 

properties affect the durability of catalysts of all types, and what fuel-derived reductants can be made with and 

without fuel additives for use with HC-SCR catalysts (ORNL). The projects designed to assess the impact of 

15-ppm sulfur diesel fuel on advanced diesel engine emission controls (light-duty and heavy-duty) to reduce 

NOx and PM emissions have been completed, and final reports will be issued (NREL, FEV, SwRI). It is 

known that sulfur has a deleterious impact on precious metal catalyst durability, even at ultra-low fuel sulfur 

contents that will exist starting in late 2006. An onboard filter that could remove the remaining sulfur would 

be highly desirable; Honeywell will conduct engine testing of their fuel sulfur removal filter and explore ways 

to decrease its size. 

Catalyst durability testing at ORNL will include accelerated catalyst poisoning tests and measurements in 

order to better define phosphorus exhaust chemistry and resulting effects on catalyst performance. New engine 

oil additives and catalyst materials and types, such as lean NOx traps (LNTs) and diesel particulate filter (DPF) 

catalysts, will be included in testing. The techniques developed to assess catalyst poisoning will be extended to 

include effects of ash and soot loading in DPFs in addition to phosphorous poisoning. Thermal aging of LNTs 

at several different lean/rich aging cycles at 900 and 1000°C will be conducted to validate repeatability of data 

and to provide more samples for surface studies to identify the progression of K migration away from the 

washcoat, the transformation of BaCO3 into other barium-mixed oxides, and sintering of the precious metal 

group. 

Investigation of the potential to produce useful fuel-derived reductants from compression-ignition fuels 

with and without fuel additives will be continued using selected reductant and catalyst combinations. 

Durability and robustness of Ag-based and other HC-SCR catalysts will be addressed with industry partners. 

(ORNL) 

11 
Fuels Technologies FY 2005 Progress Report 

The ReFUEL laboratory participates as part of the EPA/Engine Manufacturers Association (EMA) 

Calibration Standards Task Force which provides leadership and input for test methods and protocol 

specifications related to 2007-2010 EPA emissions regulations for vehicles and engines as published in the 

Code of Federal Regulations (CFR). As part of this group, ReFUEL has been selected to participate in a 

round-robin lab correlation study of a 2007 compliant engine to quantify and confirm lab-to-lab agreement and 

test methods between the nation's leading heavy-duty engine emissions laboratories on future technology 

engines with drastically reduced emissions. (NREL) 

The APBF-DEC Toxics and Unregulated Emissions team will complete summary reports for each of the 

APBF-DEC projects and a final report on all APBF-DEC unregulated emissions activities including methods 

development. 

Fuel Property Effects on Advanced Combustion Regimes 

The focus of this portion of the Fuels Technologies Sub-Program will be on how fuels properties affect 

combustion and how they can be used effectively to enhance combustion modes such as HCCI and HECC 

where emissions of NOx and PM are extremely low. To this objective, SNL will investigate how fuels such as 

biodiesel, as well as Fischer-Tropsch paraffins by themselves and in blends with conventional diesel fuel, can 

facilitate very-low-emission combustion without loss of efficiency. As part of the modeling efforts to explain 

how fuels can be combusted very cleanly, LLNL will extend its current combustion model capabilities to 

additional classes of fuel components and continue development of increasingly complex surrogate fuel 

mixtures. ORNL will continue to study emissions as a means of furthering the understanding of the 

performance of fuels in advanced combustion modes, such as HECC. 

Fuel properties are very important to HCCI combustion, and a primary objective is to expand the engine 

operating range where HCCI combustion is possible. To support this objective, ORNL will determine detailed 

chemistry effects of HCCI fuels in addition to bulk property effects such as octane, cetane, and volatility, and 

will continue to explore issues of stability and moving between various combustion regimes to determine if 

fuel chemistry can improve HCCI controllability and operating range. LLNL will modify the fueling system in 

an existing HCCI engine to demonstrate efficient and clean operation on wet ethanol. They will also 

investigate whether other marginal, low-grade fuels can be successfully utilized with HCCI engines, such as 

trash gas (natural gas with high concentration of carbon dioxide or other inert impurities). An evaluation will 

be performed to determine whether it is practical to generate HCCI additives (secondary fuels) onboard a 

vehicle to successfully control the engine. The Coordinating Research Council will conduct an experimental 

analysis of the impact of fuel properties on a light-duty HCCI engine. 

Transition to Hydrogen Economy 

Due to elimination of funding in this category of the sub-program, efforts to advance NG engine and 

vehicle technologies will be brought to an orderly conclusion in early FY 2006. 

Petroleum Displacement Fuels/Fuel Blending Components 

The focus of this portion of the Fuels Technologies Sub-Program will be on biodiesel, Fischer-Tropsch 

paraffins made from natural gas, and oil sands liquids. 

The properties of biodiesel and Fischer-Tropsch paraffins have advantages over conventional diesel fuel 

for implementation of emission control technology for diesel engines. To further explore this potential, NREL 

will collect data from heavy-duty diesel vehicles using Fischer-Tropsch diesel fuel and advanced emission 

control technology to assess emission control efficiency and durability. NREL will also test heavy-duty diesel 

engines tailored to biodiesel and biodiesel blends by varying engine operating parameters such as injection 

12 
Fuels Technologies FY 2005 Progress Report 

timing, EGR rate, and others to assess the effect on performance of diesel particle filters and NOx adsorber 

catalysts. 

A new nationwide survey of B100 and B20 quality and stability will be completed by NREL, applying 

lessons learned from 2004 and 2005 surveys. A detailed study of oxidation stability of B100, B20, and B5 will 

be completed with the objective of determining the best test method and specification limits. 

The chemical analysis developed for oil sands liquids will be extended to several upgraded streams of oil 

sands fuels by ORNL. Engine performance with the same fuel streams in normal and advanced combustion 

modes will be evaluated to understand potential fuel chemistry effects from oil sands liquids. Other near-term 

non-petroleum-based fuels such as shale-derived fuels will be identified for analysis. 

New Technology Impacts 

DOE plans to support and participate in the Advanced Collaborative Emissions Study (ACES) in 

partnership with industry and the Health Effects Institute. 

NREL will begin a proximate ozone modeling study in the southeast Michigan region in collaboration with 

state and local government groups and industry representatives in that area. 

ORNL will continue data collection of air quality and heavy truck emissions in the vicinity of I-40 in 

Knoxville, Tennessee at the Watt Road Environmental Laboratory. 

Special Honors/Recognitions 

• Charles Mueller (SNL) received the Society of Automotive Engineers Lloyd L. Withrow Distinguished 

Speaker Award. This was one of 8 such awards presented in 2005 to recognize individuals who have 

received SAE’s Oral Presentation Award more than twice. 

• Salvador M. Aceves (LLNL) invited to deliver a seminar at the SAE 2005 seminar on HCCI, September 

2005, Lund, Sweden. 

• Bruce Bunting (ORNL) was an invited speaker at the SAE Symposium on Homogeneous Charge 

Compression Ignition Combustion Engines in Lund, Sweden, September 2005. Dr. Bunting’s presentation 

was on fuel effects on HCCI. 

• Doug Lawson (NREL) was appointed by the Colorado governor to serve a three-year term on the state of 

Colorado Air Quality Control Commission. Created in 1970 by the Colorado Legislature, the Air Quality 

Control Commission develops air pollution control policy, regulates pollution sources and conducts 

hearings involving violations of the state's air pollution laws. 

• Doug Lawson (NREL) was invited to give the keynote presentation titled "The Weekend Ozone Effect: 

Reality vs. Conventional Wisdom" at the SAE Powertrain & Fluid Systems Conference in Tampa, Florida, 

October 2004. 

• Doug Lawson (NREL) was invited to make a presentation to the 50 state air pollution control 

administrators at the Environmental Council of the States annual meeting in Portland, Maine, September 

2005. 

• Doug Lawson (NREL) was invited by the California Air Resources Board (ARB) to make a webcast 

presentation describing the results of DOE's Gasoline/Diesel PM Split Study at the ARB Chairman's Air 

Pollution Seminar in Sacramento, California, September 2005. 

13 
Fuels Technologies FY 2005 Progress Report 

• Doug Lawson (NREL) was invited by the California Bureau of Automotive Repair to provide a webcast 

presentation describing DOE's Gasoline/Diesel PM Split Study and his research on EPA's high-mileage 

onboard diagnostics (OBD) study in Sacramento, California, September 2005. 

• Charles Mueller (SNL) received the Society of Automotive Engineers Arch T. Colwell Merit Award, for 

paper entitled ”Effects of Oxygenates on Soot Processes in DI Diesel Engines: Experiments and Numerical 

Simulations,” SAE Technical Paper 2003-01-1791. This was one of 11 papers honored in 2004 for being 

most innovative and original out of approximately 2,500 papers published during the preceding year. 

• Dr. Johney Green (ORNL) was selected as a Science Spectrum Trailblazer, Top Minority in Science. 

• Bruce Bunting (ORNL) was an invited speaker and session co-chair at the 2005 International Conference 

for Automotive Technology in Vietnam in October 2005. 

Patents Issued 

• Controlling and Operating Homogeneous Charge Compression Ignition (HCCI) Engines, 

Daniel L. Flowers (LLNL), United States Patent 6,923,167, August 2, 2005. 

Summary 

The work being conducted in Fuels Technologies on conventional, non-petroleum-based, and renewable 

fuels complements the efforts to build advanced engines and fuel cells for use in transportation applications. 

High-efficiency prime movers such as compression ignition, direct injection engines need clean fuels with 

carefully defined properties to enable fuel-efficient light-duty and heavy-duty vehicles with the attributes that 

consumers demand. Highly fuel-efficient vehicles with very low emissions are essential to meet the challenges 

of climate change, energy security, and improved air quality. As the new fiscal year begins, we look forward to 

on-going and new cooperative efforts with the auto and energy industries to develop new and innovative fuels 

technologies for use in advanced transportation vehicles that are fuel-efficient, clean, and safe. 

Stephen Goguen Kevin Stork 

Team Lead Technology Development Manager 

Fuels Technologies Fuels Technologies 

Office of FreedomCAR and Office of FreedomCAR and 

Vehicle Technologies Vehicle Technologies 

14 
Fuels Technologies FY 2005 Progress Report 

II Fuels and Lubricants to Enable High 

Efficiency Engine Operation while Meeting 

2007 - 2010 Standards

15 
Fuels Technologies FY 2005 Progress Report 

16
Fuels Technologies FY 2005 Progress Report 

II.1 Development of a Passenger Car Test Platform to Evaluate NOx 

Adsorber/DPF Systems Using Ultra-Low Sulfur Fuels 

Matthew J. Thornton 

National Renewable Energy Laboratory 

1617 Cole Blvd., MS 1633 

Golden, CO 80401 

DOE Team Lead: Stephen Goguen 

DOE Technology Development Manager: Kevin Stork 

Other Participants: 

American Petroleum Institute, Engine Manufacturers Association, Manufacturers of Emissions Control Association 

(MECA), U. S. Environmental Protection Agency (EPA), Oak Ridge National Laboratory, California Air Resources Board

Subcontractor: 

FEV Engine Technology, Auburn Hills, MI 

Objectives 

• To use a systems approach to demonstrate the potential of NOx adsorber catalyst (NAC) technology in 

combination with diesel particle filters (DPFs), advanced fuels, and advanced engine controls to achieve 

low emission levels while maintaining high fuel economy. That is, to meet stringent Tier 2 Bin 5 lightduty vehicle emission standards with limits of 0.07 g/mi NOx and 0.01 g/mi particulate matter (PM). 

• To help determine the necessary fuel sulfur level and other fuel properties that will enable these systems. 

The fuel sulfur levels tested were representative of those required to be available beginning June 2006 

(<15 ppm S). 

Approach 

A model year 2001 Audi A4 Avant with a 1.9 liter TDI engine (100 KW at 4000 rpm) with a Bosch common 

rail second generation fuel injection system, integrated exhaust gas recirculation (EGR) and a Garett GT 17 V 

turbocharger was used as the test vehicle for this project. This vehicle was equipped with appropriately 

designed emission control devices and the necessary NAC regenerative control hardware and electronics to 

conduct this fuel study, which encompasses two primary tasks: 

• Task A involved development of the test platform, including setup, integration, and optimization of the 

engine; rapid warm-up testing and thermal management; emission control system (ECS) and associated 

electronic controls; and baseline (engine-out) testing of regulated and unregulated (toxic) emissions. 

• Task B involved system performance and aging tests using fuels with varying sulfur content (8 and 15 ppm 

S) and periodic evaluations of emissions over the Urban Dynamometer Driving Schedule (UDDS), US06, 

and Highway Fuel Economy Test (HFET) during aging tests up to 2200 hours of operation (full useful life 

equivalent, approximating 120,000 miles of operation). Two ECS architectures (A and B) were developed 

and tested, both being single-leg systems. 

17 
Fuels Technologies FY 2005 Progress Report 

Accomplishments 

• Completed Task A, the development of all control strategies related to the optimization of the ECS. This 

included the NAC regeneration strategy, DPF regeneration strategy, and NAC desulfurization strategy and 

the sampling and analysis of baseline engine-out emissions. 

• Completed the sampling and analysis of the emissions for ECS-A and ECS-B with both 8- and 15-ppm 

sulfur fuels through 50 hours of aging. 

• Completed Task B, the sampling and analysis of the emissions for ECS-B (the best-performing system) 

with 15-ppm sulfur fuel through 2200 hours of aging. 

Future Directions 

• Complete final report. 

Introduction 

The Advanced Petroleum Based Fuels – Diesel 

Emission Control (APBF-DEC) activity is a joint 

government/industry research effort to determine the 

best combinations of low-sulfur diesel fuels, 

lubricants, diesel engines, and emission control 

systems to meet projected emission standards for the 

2002 to 2010 time period. The project leverages the 

participation of several multi-industry working 

groups that direct five individual projects. 

This project aimed to demonstrate the viability of 

utilizing simultaneously NOx adsorber catalyst 

(NAC) and diesel particle filter (DPF) technologies 

in combination with clean fuels, advanced engines 

and electronic controls to achieve low emission 

levels while maintaining high fuel economy. 

Specifically, this project will identify the fuels 

needed to enable these technologies for use in lightduty vehicles. The goal for this platform is to meet 

Tier 2 Bin 5 light-duty emission standards with limits 

of 0.07 g/mi NOx and 0.01 g/mi PM. 

Another critical focus of this project is the 

characterization of currently unregulated, but 

potentially toxic emissions. 

Among the fuel variables to be studied, sulfur 

has been identified as most critical to this research. 

The Diesel Emission Control – Sulfur Effects 

(DECSE) project [1], a predecessor to this effort, 

examined the effect of sulfur on individual emission 

control devices including NACs, DPFs, diesel 

oxidation catalysts, and lean NOx catalysts. This 

testing showed that efficiency of NACs is 

significantly affected by sulfur in the diesel fuel [2]. 

This project provides a more thorough investigation 

of sulfur effects and uses modern hardware and 

robust electronic controls with systems incorporating 

both NOx and PM control devices. ECS 

performance over time, as a function of fuel sulfur 

exposure, was examined in tests up to 2200 hours in 

duration (approximating 120,000 miles of driving). 

Approach 

A model year 2001 Audi A4 Avant (Figure 1) 

with a 1.9 liter TDI engine (100 KW at 4000 rpm) 

(Figure 2) with a Bosch common rail second 

generation fuel injection, integrated exhaust gas 

recirculation (EGR) and a Garett GT 17 V 

turbocharger will be used as the test vehicle for this 

project. This vehicle was equipped with 

appropriately designed emission control devices and 

the necessary NAC regenerative control hardware 

and electronics to conduct this fuel study. 

A significant reduction (80-90%) in tailpipe 

Figure 1. Audi A4 Avant Test Vehicle 

18 
Fuels Technologies

Figure 2. 1.9 L TDI Test Engine 

emissions over the current European calibration for 

this vehicle was required for this project. 

In order to make the goals of this project possible 

and limit the reduction efficiencies required by the 

ECS devices, significant modifications were made to 

the test engine by the subcontractor to lower engineout emissions, including installation of common rail 

fuel injectors, addition of aluminum cylinder heads, 

and engine calibration changes (for lower engine-out 

NOx and more favorable exhaust temperature 

profiles). In addition, dual wall insulated exhaust 

components were used to retain heat for the ECS 

created by the engine. MECA provided emission 

control devices for two different ECS configurations 

(denoted as ECS-A and ECS-B), both single-leg 

systems. Figure 3 shows the basic configuration for 

both systems, with the key difference being the 

formulation of the pre-catalyst. In ECS-A the 

pre-catalyst will serve both a NOx adsorbing and 

oxidizing function, while in system ECS-B the 

pre-catalyst will only serve a NOx adsorbing 

function. 

This project was comprised of two primary tasks: 

Task A involved development of the test 

platform, including setup, integration, and 

optimization of the engine and vehicle, ECS and 

associated electronic controls, and development of 

 FY 2005 Progress Report 

thermal management strategies. This task included 

the design of post injection strategies that provided 

in-cylinder secondary fuel for NOx adsorber catalyst 

regeneration. The primary result of this task was the 

development of all control strategies related to the 

optimization of the ECS. This included the NAC 

regeneration strategy, DPF regeneration strategy, and 

NAC desulfurization strategy. 

This task also included baseline tests to 

characterize engine-out emissions (no catalysts) 

during transient and steady-state operation. Baseline 

tests were conducted with DECSE 8- and 15-ppm 

sulfur fuels (referred to as D8 and D15) and a lowsulfur refinery fuel (referred to as BP15). The 

information and results from this task were included 

in previous years’ reports and can be referenced in 

these reports or the publications listed at the end of 

this report [3]. 

Task B involved system performance and aging 

evaluations using fuels with varying fuel sulfur 

content. Performance evaluations on the UDDS, 

US06, and HFET driving cycles were conducted at 0 

and 50 hours using 8- and 15-ppm S fuels. Aging 

continued on one of these systems for an additional 

2150 hours using the 15-ppm S fuel to determine 

longer-term aging impacts. The results of these tests 

are included in the following section. 

A full suite of emissions were measured during 

both Task A baseline testing and Task B aging tests. 

They included the following: 

– NOx (oxides of nitrogen) 

– CO (carbon monoxide) 

– HC (hydrocarbons)

– CO2 (carbon dioxide)

Figure 3. Emission Control System Architecture 

19 
Fuels Technologies FY 2005 Progress Report 

– PM (including detailed compositional 

analysis) 

– Benzene 

– 1,3 butadiene

– Formaldahyde

– Acetaldehyde

– N2O (nitrous oxide)

– NH3 (ammonia)

– SO2 (sulfur dioxide)

– H2S (hydrogen sulfide)

– Nitroxyalkanes 

Results 

Once all of the ECS control features were 

incorporated into a final strategy, the refined 

calibration was applied to both ECS-A and ECS-B. 

Engine dynamometer tests were performed on the 1.9 

liter TDI test engine over the cold- and hot-start 

USSD, US06, and HFET driving cycles. The UDDS, 

also known as the LA4, cycle is composed of Bag 1 

and Bag 2 of the light-duty Federal Test Procedure 

(FTP) cycle. The US06 is a high speed/load 

aggressive test procedure, part of the supplemental 

FTP, and the HFET is the highway fuel economy test 

cycle. 

All tests reported here were simulations of the 

actual driving cycles discussed above, performed by 

FEV in their engine test cell. The first test during 

each testing sequence was the FTP in its modified 

form (2 consecutive UDDSs). There were two 

(instead of three) bag and filter measurements taken 

per test. The calculation of the final result was a 

composite UDDS, algebraically equal to a standard 

FTP three-bag test (43% weighting on the cold-start 

UDDS and 57% weighting on the hot-start UDDS). 

This discussion summarizes the aging results 

through 1220 hours of testing as they relate to NOx 

and PM emissions and NOx trends over the 

composite UDDS. One cold-start and multiple hotstart UDDS tests were run each day to accumulate 

operating time, since the engine would otherwise 

need to be force-cooled or soaked overnight between 

each cold-start test. These data are presented as 

averages of two or three tests at each evaluation 

point, including engine-out measurements shown on 

the left side of each figure. The majority of the 

evaluations were conducted with the DECSE 15 ppm 

sulfur fuel, denoted as D15, with occasional 

duplicate evaluations using a refinery run 15 ppm 

sulfur fuel, denoted as BP15. A distinction is made 

in all of the following figures when D15 versus BP15 

fuel was used. In addition, the figures include the 

occurrence of a NOx adsorber desulfation event, 

indicated by vertical dashed lines; the 50,000-mile 

interim useful life Tier 2 Bin 5 emissions standard, 

indicated by the green dashed horizontal lines; and 

the 120,000-mile full useful life Tier 2 Bin 5 

standard, indicated by the green solid horizontal 

lines. 

During the course of aging, the catalyst system 

was evaluated frequently in order to assess its 

degradation in performance due to sulfur poisoning 

and thermal aging. The initial tests were performed 

at 0 hours with fresh catalysts. The subsequent test 

series were performed before and after the 

desulfurization events at 150 and 300 hours of aging. 

After the 300-hour mark, the desulfurization/ 

evaluation cycle frequency was increased to every 

100 hours up to 1600 hours of aging. Starting at 

1600 hours, desulfurizations and evaluations were 

performed every 50 hours. 

The average NOx emission results are displayed 

in Figure 4. Observations at the beginning and end 

of a single aging cycle are connected. 

With the increased desulfurization frequency, the 

composite FTP tailpipe NOx emissions post 

desulfurization after 2200 hours could be maintained 

below the emission standard for 120,000 miles of 

0.07 g/mile. A detailed statistical analysis of NOx 

emissions results from the test cell is discussed in the 

following section. 

The evaluation of the PM filters showed the high 

degree of filtration efficiency of the DPF, as shown in 

Figure 5. There were two instances where the 

composite PM numbers were above the emission 

standard of 0.01 g/mi. These higher emission 

numbers were a result of a high soluble organic 

fraction on the cold UDDS filters. After a DPF 

failure during the 1000-hour vehicle tests, the DPF 

was replaced, and the aging testing was continued. 

The filtration efficiency for the new DPF remained 

on the high level as observed with the first DPF. 

20 
Fuels Technologies

Statistical analyses were performed to 

characterize trends in emissions levels over the 2200 

hours of testing. To account for the evaluations 

consisting of only the hot UDDS cycles, an 

imputation method was developed to estimate the 

cold UDDS and resulting FTP composite results. 

The statistical analysis is based on a combination of 

imputed and actual FTP composite results. 

Figure 6 illustrates the degradation in catalyst 

performance between desulfurizations and the 

effectiveness of the desulfurization process at 

restoring performance. A log-linear model was fit to 

estimate average trends and evaluate statistical 

significance. The upper graph demonstrates that the 

average loss in NOx reduction efficiency (FTP 

composite) between desulfurizations varies between 

Figure 4. FTP Composite NOx Results during Aging 

Study (desulfation frequency is noted by gray 

dashed lines) 

Figure 5. FTP Composite PM Results during Aging 

Study (desulfation frequency is noted by gray 

dashed lines) 

 FY 2005 Progress Report 

15% and 35% prior to 1600 hours. After the 

desulfurization strategy changed at 1600 hours, the 

loss in NOx reduction efficiency was generally 10%. 

There was a slight drop between 1800 and 2000 

hours that could not be explained. 

The lower graph demonstrates that prior to 1600 

hours there was an increase in average NOx 

reduction efficiency of 10% to 35% at each 

desulfurization event. After 1600 hours, there is on 

average a 10% improvement in NOx reduction 

efficiency at each desulfurization event, with a 

higher trend between 1800 and 2000 hours. 

Combined, these graphs indicate that the 

performance of the desulfurization process was 

relatively unstable with the 100-hour desulfurization 

strategy, but was quite consistent with the 50-hour 

desulfurization strategy. 

The trends in FTP composite NOx reduction 

efficiency relative to engine-out emissions between 

Figure 6. NOx Reduction Efficiency Behavior over 

Time 

21 
Fuels Technologies

300 and 1600 hours and between 1600 and 2200 

hours of aging are shown in Figure 7. To account for 

the effects of the desulfurization process, separate 

log-linear models were fit to three sets of NOx 

emissions data: (1) measurements made before a 

desulfurization event, (2) measurements made after a 

desulfurization event, and (3) the average of 

measurements made at the beginning (postdesulfurization) and end (pre-desulfurization) of each 

aging period. The latter results plotted at the 

midpoint of the aging period represent the best 

estimate of the average emissions over time; 

however, we could not verify that the increase in 

NOx emissions within an aging period is linear. 

Both the average and pre-desulfurization loglinear regression lines shown in Figure 7, based on 

the 100-hour desulfurization data, were found to 

have statistically significant trends. However, 

because of the curvature in the trends, additional 

analyses were performed to address the question of 

whether the performance of the system stabilizes 

over time. This was accomplished by iteratively 

truncating the left-most data from each of the three 

data sets, then refitting the regression model and 

evaluating the significance of the regression slope 

parameter. Through this process, it was determined 

that the trends are not statistically significant after 

700 hours of aging with a 100-hour desulfurization 

strategy. None of the regression lines shown in 

Figure 7, based on the 50-hour desulfurization data, 

were found to have statistically significant trends. 

Figure 7. NOx Emission and Reduction Efficiency 

Trends over Time 

 FY 2005 Progress Report 

Fuel consumption data were collected over the 

UDDS composite during the aging and evaluation 

events for this project. The average fuel economy for 

the baseline engine-out tests was 34.5 miles per 

gallon (mpg), compared with the average fuel 

economy during the ECS evaluation events of 32.5 

mpg. This equated to a 5.8% fuel economy penalty 

for the NAC/DPF system. Despite this penalty, these 

data, combined with the NOx emissions data, 

indicate that a light-duty diesel can achieve low 

emissions while maintaining superior fuel economy. 

The adjusted EPA city cycle fuel consumption for the 

vehicle with the ECS is 29 mpg (54 mpg adjusted 

highway cycle), which is a 38% improvement over 

the gasoline version of the A4 Avant wagon (21 mpg 

adjusted city cycle) and a 26% improvement over a 

comparable SULEV (approximate Tier 2 Bin 5 

vehicle) Honda Accord (23 mpg adjusted city cycle). 

Just as important, the fuel consumption has remained 

steady and has not shown any indication of 

increasing with ECS aging. 

Subsequent to the UDDS tests, the US06 cycle 

was conducted. The US06 cycle was developed by 

the EPA to capture driving events not included in the 

FTP-75. Due to the aggressive nature of this test 

cycle, including steep accelerations and high vehicle 

speed, the emission numbers are higher than 

observed during the UDDS. However, the NOx 

emissions are still on a level of 0.2 g/mile and lower. 

Due to the light load of the HFET (in conjunction 

with the hot-start), the emissions measured over this 

cycle are below the minimum detection level. All 

gaseous emissions are on a very low level. 

A more complete set of results, including all 

pollutant emissions (i.e., criteria pollutant, toxic, and 

unregulated emissions), will be included in next 

year’s final report for this project. 

Conclusions 

The developed integrated concept, which 

incorporates software and hardware solutions, shows 

considerable potential for meeting future emission 

standards. Important aspects during the development 

were the modifications of the test engine and the 

engine-out emissions optimization. With the 

adjusted engine-out emissions level, the exhaust ECS 

22 
Fuels Technologies FY 2005 Progress Report 

interventions were defined, developed, and refined. 

Due to the large portion of cold-start emissions, the 

rapid warm-up strategy, allowing fast catalyst lightoff, was optimized. DPF desulfurization and 

regeneration strategies were developed focusing on 

catalyst long-term performance and fuel 

consumption. There are remaining challenges that 

need to be addressed, such as the increase in HC 

emissions over the catalyst life. 

Test work associated with this activity is 

complete, and final data analysis and reporting will 

be published in 2006. 

FY 2005 Publications/Presentations 

1. Tomazic D., Tatur M., Tyrer H., Thornton M., 

McDonald J., “Tier 2 Intermediate Useful Life 

(50,000 miles) and 4000 Mile Supplemental Federal 

Test Procedure (SFTP) Exhaust Emission Results for 

a NOx Adsorber and Diesel Particle Filter Equipped 

Light-Duty Diesel Vehicle,” SAE Paper 

2005-01-1755, March 2005, Detroit, Michigan. 

2. Information from this project was also presented at 

the Diesel Engine Emission Reduction (DEER) 

Conference in Chicago, Illinois, in August 2005. 

References 

1. http://www.ott.doe.gov/decse/ 

2. U.S. Department of Energy, Engine Manufacturers 

Association, Manufacturers of Emission Controls 

Association, “Diesel Emission Control – Sulfur 

Effects (DECSE) Program – Phase I Interim Data 

Report No. 2: NOx Adsorber Catalysts,” October 

1999. 

3. Tomazic, Tatur, and Thornton, “Development of a 

Diesel Passenger Car Meeting Tier 2 Emissions 

Levels,” SAE Paper 2004-01-0581, March 2004. 

23 
Fuels Technologies FY 2005 Progress Report 

II.2 Development of a Pick-up/SUV Test Platform to Evaluate NOx 

Adsorber/DPF Systems Using Ultra-Low Sulfur Fuels 

Matthew J. Thornton 

National Renewable Energy Laboratory 

1617 Cole Blvd., MS 1633 

Golden, CO 80401 

DOE Team Lead: Stephen Goguen 

DOE Technology Development Manager: Kevin Stork 

Other Participants: 

American Petroleum Institute, Engine Manufacturers Association, Manufacturers of Emissions Control Association 

(MECA), U. S. Environmental Protection Agency, Oak Ridge National Laboratory, California Air Resources Board

Subcontractor: 

Southwest Research Institute, San Antonio, TX 

Objectives 

To use a systems approach to demonstrate the potential of NOx (oxides of nitrogen) adsorber technology in 

combination with diesel particulate filters, advanced fuels, and advanced engine controls to achieve low 

emission levels while maintaining high fuel economy. That is, to meet stringent Tier 2 Bin 5 light-duty 

emission standards with limits of 0.07 g/mi NOx and 0.01 g/mi particulate matter (PM). To help determine the 

necessary fuel sulfur level and other fuel properties that will enable these systems. The fuel sulfur levels tested 

were representative of those required to be available beginning June 2006 (<15 ppm S). 

Approach 

A 6.6 liter Duramax engine (300 HP at 3100 rpm) with a Bosch common rail fuel injection, integrated exhaust 

gas recirculation (EGR), charge air cooler, and a center mounted turbocharger was used as the test engine for 

this project. The vehicle was equipped with appropriately designed emission control devices and the necessary 

regenerative control hardware and electronics to conduct this study, which encompasses two major tasks: 

• Task A involved development of the test platform, including setup, integration, and optimization of the 

engine, thermal management; emission control system (ECS) and associated electronic controls; and 

baseline (engine-out) testing of regulated and unregulated (toxic) emissions. 

• Task B involved system performance and aging tests using fuels with 15 ppm sulfur content and periodic 

evaluations of emissions over the Federal Test Procedure (FTP), US06, and Highway Fuel Economy Test 

(HFET) driving cycles during aging tests up to 2000 hours of duration. One dual-leg ECS architecture was 

developed and tested during this task. 

Accomplishments 

• Completed Task A development of all control strategies related to the optimization of the ECS, which 

include the NOx adsorber catalyst (NAC) regeneration strategy, diesel particulate filter (DPF) regeneration 

strategy, and NAC desulfurization strategy. 

• Completed Task B sampling and analysis of the emissions for the ECS with 15-ppm sulfur fuels through 

2000 hours of aging. 

24 
Fuels Technologies FY 2005 Progress Report 

Future Directions 

• Complete final report. 

Introduction 

The Advanced Petroleum Based Fuels – Diesel 

Emission Control (APBF-DEC) activity is a joint 

government/industry research effort to determine the 

best combinations of low-sulfur diesel fuels, 

lubricants, diesel engines, and emission control 

systems to meet projected emission standards for the 

2002 to 2010 time period. The activity leverages the 

participation of several multi-industry working 

groups that direct five individual projects. 

This project aimed to demonstrate the viability of 

simultaneously utilizing NOx adsorber catalysts and 

DPF technologies in combination with clean fuels, 

advanced engines and electronic controls to achieve 

low emission levels while maintaining high fuel 

economy. Specifically, this project will identify the 

fuels needed to enable these technologies for use in 

light-duty vehicles. The goal for this engine/ECS 

test platform is to meet Tier 2 Bin 5 light-duty 

emission standards with limits of 0.07 g/mi NOx and 

0.01 g/mi PM. Another critical focus of this project 

is the characterization of currently unregulated, but 

potentially toxic emissions. 

Among the fuel variables to be studied, sulfur 

has been identified as most critical to this research. 

The Diesel Emission Control – Sulfur Effects 

(DECSE) project [1], a predecessor to this effort, 

examined the effect of sulfur on individual emission 

control devices, including NOx adsorber catalysts, 

DPFs, diesel oxidation catalysts, and lean NOx 

catalysts. This testing showed that the efficiency of 

NOx adsorber catalysts is significantly affected by 

sulfur in the diesel fuel [2]. This project provides a 

more thorough investigation of sulfur effects and 

uses modern hardware and robust electronic controls 

with systems incorporating both NOx and PM 

control devices. ECS performance over time, as a 

function of fuel sulfur content, was examined in tests 

up to 2000 hours in duration. 

Figure 1. 6.6 L Duramax Test Engine 

Approach 

A 6.6 liter Duramax engine (300 HP at 3100 

rpm) (Figure 1) with a Bosch common rail fuel 

injection, integrated exhaust gas recirculation (EGR), 

charge air cooler, and a center mounted turbocharger 

was used as the test engine for this project. This 

vehicle was equipped with appropriately designed 

emission control devices and the necessary 

regenerative control hardware and electronics to 

conduct this fuel study. A significant reduction in 

tailpipe emissions over the current California 

calibration for this engine was required for this 

project. 

In order to make the goals of this project possible 

and limit the reduction efficiencies required by the 

ECS devices, significant modifications have been 

made to the test engine by the subcontractor in order 

to lower engine-out emissions, including installation 

of low-pressure EGR and engine calibration changes 

(for lower engine-out NOx and more favorable 

exhaust temperature profiles). In addition, secondary 

fuel injection, a diesel fuel burner, and dual wall 

insulated exhaust components were used for thermal 

25 
Fuels Technologies FY 2005 Progress Report 

Figure 2. Emission Control System Architecture 

management of the ECS. A MECA supplier 

provided emission control devices for the project 

dual-leg ECS configuration. Figure 2 shows the 

basic configuration for the system. This system 

minimized NOx breakthrough as well as the fuel 

penalties associated with NOx reduction, but was 

complex and expensive. This project is comprised of 

two major tasks: 

Task A involved development of the test 

platform, including setup, integration, and 

optimization of the engine and vehicle, ECS and 

associated electronic controls, and development of 

thermal management strategies. This task included 

the design of post injection strategies that provide 

in-cylinder secondary fuel for NOx adsorber catalyst 

regeneration (3,4). This task also included baseline 

tests to characterize engine-out emissions 

(no catalysts) during transient and steady-state 

operation. Baseline tests were conducted with a 

DECSE 15-ppm sulfur fuel (referred to as D15) and 

a low-sulfur refinery fuel (referred to as BP15). 

Task B involved system performance and aging 

evaluations using a 15-ppm sulfur fuel (D15 and 

BP15), with performance evaluations over the FTP, 

US06 and HFET driving cycles conducted every 50 

hours up to 300 hours. Aging was continued on the 

ECS for an additional 1700 hours using the 15-ppm 

sulfur fuel to determine longer-term aging impacts. 

A full suite of emissions were measured during 

Task A baseline testing and Task B aging tests. They 

include the following: 

• NOx 

• CO 

• HC (hydrocarbons) 

• CO2 (carbon dioxide) 

• PM (including detailed compositional analysis) 

• Benzene 

• 1,3 butadiene 

• Formaldahyde 

• Acetaldehyde 

• N2O (nitrous oxide) 

• NH3 (ammonia) 

• SO2 (sulfur dioxide) 

• H2S (hydrogen sulfide) 

• Nitroxyalkanes 

Results 

Once all of the ECS control features were 

incorporated into a final strategy, the refined 

calibration was applied to the ECS configured 

engine. Engine dynamometer tests were performed 

on the 6.6 liter Duramax over the cold- and hot-start 

Urban Dynamometer Driving Schedule (UDDS), 

US06, and HFET driving cycles. The UDDS, also 

known as the LA4, cycle is composed of Bag 1 and 

Bag 2 of the light-duty FTP; the US06 is a high 

speed/load aggressive test procedure, part of the 

supplemental FTP; and the HFET is the highway fuel 

economy test cycle. 

All tests reported here were simulations of the 

actual driving cycles discussed above, performed by 

Southwest Research Institute in their engine test cell. 

The first test during each testing sequence was the 

FTP in its modified form (2 consecutive UDDSs). 

There were two (instead of three) bag and filter 

measurements taken. The calculation of the final 

result was a composite UDDS, algebraically equal to 

a standard FTP three-bag test (43% weighting on the 

cold-start UDDS and 57% weighting on the hot-start 

UDDS). 

This discussion summarizes the complete aging 

results through 2000 hours of testing as they relate to 

NOx and PM emissions and NOx trends over the 

composite UDDS. This was done as a time-saving 

method that would allow for multiple hot-start 

26 
Fuels Technologies FY 2005 Progress Report 

Figure 3. Cold- and Hot-Start UDDS NOx Emissions 

UDDS tests to be run in a single day, since the engine 

would need to be force-cooled or soaked over night 

between each cold-start test. These data are 

presented as averages of two or three tests at each 

evaluation point. The majority of the evaluations 

were conducted with the DECSE 15-ppm sulfur fuel, 

denoted as D15, with occasional duplicate 

evaluations using a refinery run 15-ppm sulfur fuel, 

denoted as BP15. A distinction is made in all of the 

following figures when BP15 versus D15 fuel was 

used. The figures also include the occurrence of a 

NOx adsorber desulfation event, indicated by vertical 

dashed lines; the 50,000 mile interim useful life Tier 

2 Bin 5 emission standard, indicated by the green 

dashed horizontal lines; and the 120,000 mile full 

useful life Tier 2 Bin 5 standard, indicated by the 

green solid horizontal lines. 

During the course of aging, the catalyst system 

was evaluated frequently in order to assess its 

degradation in performance due to sulfur poisoning 

and thermal aging. The initial tests were performed 

at 0 hours with fresh catalysts. The subsequent test 

series were performed before and after the 

desulfurization events at 200 and 300 hours of aging. 

After the 300-hour mark, the desulfurization/ 

evaluation cycle frequency was increased to every 

100 hours through the remainder of the 2000 hours of 

aging. 

The average NOx emission results are displayed 

in Figures 3 and 4. Observations at the beginning 

and end of a single aging cycle are connected. Coldand hot-start UDDS cycles were performed at the 

Figure 4. Composite FTP NOx Emissions 

Figure 5. Composite PM Emissions 

aging marks depicted in Figure 3, and the composite 

FTP emissions are illustrated in Figure 4. 

With the given desulfurization frequency, the 

composite FTP tailpipe NOx emission number post 

desulfurization after 2000 hours could not be 

maintained below the emission standard for 120,000 

miles of 0.07 g/mile. A detailed statistical analysis 

of NOx emissions results from the test cell is 

discussed in the following section. 

The evaluation of the PM filters showed the high 

degree of filtration efficiency of the DPF. In all 

instances throughout the aging, the average 

composite PM numbers were below the emission 

standard of 0.01 g/mi, as shown in Figure 5. 

Statistical analyses were performed to 

characterize trends in emission levels over the 2000 

hours of testing. 

27 
Fuels Technologies FY 2005 Progress Report 

Figure 6. Change in NOx Reduction Efficiency Between 

Desulfurizations over Time 

Figure 8. Emission Trends over Time 

Figure 7. Increase in NOx Reduction Efficiency at 

Desulfurizations over Time 

Figure 9. NOx Reduction Efficiency Trends over Time 

Figure 6 illustrates the degradation in catalyst 

performance between desulfurizations. A log-linear 

model was fit to estimate average trends and evaluate 

statistical significance. The graph demonstrates that 

the loss in NOx reduction efficiency (FTP 

composite) between desulfurizations is generally 

about 6% of the engine-out without EGR, with a 

slight trend ranging between 4% and 6%. Figure 7 

illustrates the effectiveness of the desulfurization 

process at restoring performance. There is a 6% 

improvement in NOx reduction efficiency at each 

desulfurization event, with a slight trend ranging 

between 3% and 6%. Although these trend lines 

show slight changes in NOx reduction efficiency, the 

slopes of the regression lines were not statistically 

different from zero. Combined, these figures 

indicate that the desulfurization process generally 

compensates for the increased degradation in catalyst 

performance between desulfurizations throughout the 

2,000-hour test. 

The trends in FTP composite NOx emissions 

between 300 and 2000 hours of aging are shown in 

Figure 8, and trends in FTP composite NOx 

reduction efficiency relative to engine-out between 

300 and 2000 hours of aging are shown in Figure 9. 

To account for the effects of the desulfurization 

process, separate log-linear models were fit to three 

sets of NOx emissions data: (1) measurements made 

before a desulfurization event, (2) measurements 

made after a desulfurization event, and (3) the 

average of measurements made at the beginning 

(post-desulfurization) and end (pre-desulfurization) 

of each aging period. The latter results plotted at the 

midpoint of the aging period represent the best 

28 
Fuels Technologies FY 2005 Progress Report 

estimate of the average emissions over time; 

however, it could not be verified that the increase in 

NOx emissions within an aging period is linear. 

The plots in Figures 8 and 9 show the 

performance stabilization for the systems over time. 

All three of the regression lines were found to have 

statistically significant trends at the 95% confidence 

level. However, because of the curvature in the 

trends, additional analyses were performed to 

address the question of whether the system stabilizes 

over time. This was accomplished by iteratively 

truncating the leftmost data from each of the three 

data sets, then refitting the regression model and 

evaluating the significance of the regression slope 

parameter. The trends are not statistically significant 

after 800 to 900 hours of aging. 

Table 1 shows the average composite FTP 

emissions from the seven engine-out tests (six 

without EGR and one with EGR) and from the 18 

tailpipe tests conducted prior to the first 

desulfurization at 200 hours, as well as the estimated 

FTP composite emissions results at 1950 hours as 

determined by the average trend line based upon 

measurements taken between 350 and 1950 hours. 

Emission reductions are calculated relative to engineout with and without EGR. Emission reduction does 

not necessarily equate to NOx conversion because 

backpressure affects engine-out emissions by 

changing the amount of EGR in use. 

The initial and 1950-hour estimated reductions in 

NOx, CO, and PM emissions due to the ECS were all 

statistically significant, as was the reduction in fuel 

Table 1. Average Engine-Out, Initial, and Estimated 1950-Hour Tailpipe Composite FTP Regulated Emissions and Fuel 

Economy 

Emission 

Parameter 

EGR EngineOut Tailpipe (0-200 Hours) Tailpipe Average 

(Post-Pre)5 (1950 Hours) 

Regulated 

Emission 

Standard 4 

Avg.

1 Avg.2 Percent 

Reduction 

Avg.

3 Percent 

Reduction 

NOx 

(g/mi) 

Without 4.38 

0.095 

97.8% 

0.616 

85.9% 

0.07 

With 2.12 95.5% 70.9% 

NMHC 

(g/mi) 

Without 0.198 

0.165 

16.7% 

0.372 

-87.6% 

0.09 

With Missing Missing Missing 

THC 

(g/mi) 

Without 0.204 

0.463 

-126.9% 

0.730 

-257.8% N/A 

With 0.264 -75.1% -176.2% 

CO 

(g/mi) 

Without 2.02 

0.258 

87.2% 

0.620 

69.3% 

4.2 

With 4.43 94.2% 86.0% 

PM 

(g/mi) 

Without 0.065 

0.005 

91.6% 

0.005 

91.8% 

0.01 

With 0.145 96.2% 96.3% 

FE 

(mi/gal) 

Without 18.4 

15.0 

18.7% 

15.5 

16.0% 

N/A

With 18.0 16.7% 13.9% 

1 Engine-out average without EGR is based on 6 tests; Engine-out average with EGR is based on 1 test 

2 Average of 18 tests performed prior to first desulfurization at 200 hours 

3 Estimate at 1950 hours based upon the trend of average results between 350 and 1950 hours 

4 Tier 2 Bin 5 Full Useful Life 

5 The average of the post-desulfurization measurement at 1900 hours and the following pre-desulfurization measurement at 2000 hours 

N/A = Not applicable 

29 
Fuels Technologies

economy (initially 18.7% relative to engine-out 

without EGR and 16.7% relative to engine-out with 

EGR). Although initially the average tailpipe NOx 

emissions of 0.095 g/mi were higher than the 

regulated emissions standard of 0.07 g/mi, the 

difference was not statistically significant. The 

1950-hour estimate of 0.616 g/mi was significantly 

above the standard. Initial average non-methane 

hydrocarbon (NMHC) emissions of 0.165 g/mi were 

83% higher than the applicable standard, and the 

estimated 1950-hour average NMHC emissions of 

0.372 g/mi were over four times the applicable 

standard. Tailpipe emissions for total hydrocarbons 

(THC) were greater than engine-out THC emissions, 

and average PM emissions were 50% lower than the 

applicable standard throughout. 

Fuel consumption data was collected for the 

composite UDDS during the aging and evaluation 

events. The average fuel economy for the baseline 

engine-out tests was 18.3 mpg, compared with the 

average fuel economy during the ECS evaluation 

events of 14.9 mpg. This equates to an 18.6% fuel 

economy penalty for the NAC/DPF system. This 

fuel economy penalty is large, but it should be noted 

that the majority of the total penalty (53%) is 

associated with the diesel fuel burner operation. 

With a smaller displacement engine and associated 

higher exhaust temperatures, less burner assist would 

be required, resulting in a lower fuel penalty. Indeed, 

the fuel penalty associated with the NAC 

regeneration over the composite UDDS is only 6%. 

The impact of the burner operation on the fuel 

penalty is further illustrated when the fuel 

consumption from the US06 cycles is considered. 

The US06 cycle is a more aggressive cycle than the 

UDDS, resulting in higher exhaust temperatures and, 

in turn, less need for the burner. The overall fuel 

penalty associated with the US06 cycle is only 5.2%. 

Conclusions 

During the course of this project, it was 

demonstrated that the NAC/DPF system evaluated, 

in conjunction with a 15-ppm sulfur fuel and 

appropriate control strategies and calibrations, could 

 FY 2005 Progress Report 

achieve high NOx and PM reduction efficiencies. 

After 2000 hours of on-engine aging, the NAC/DPF 

system demonstrated an average NOx reduction of 

89% and PM reduction of 94% over the composite 

FTP. While the PM emissions were below the Tier 2 

Bin 5 emission standard, the NOx emissions were 

outside of this limit after full aging. The 

desulfurization strategy employed was successful in 

recovering NOx adsorber performance, with some 

deterioration through 2000 hours of aging. 

The ECS evaluated, in conjunction with 15-ppm 

sulfur fuel, achieved a high NOx reduction level over 

the course of 2000 hours of aging and was also able 

to achieve Tier 2 Bin 5 PM levels during early stages 

of aging. 

Test work associated with this activity is 

complete, and final data analysis and reporting will 

be published in 2006. 

FY 2005 Publications/Presentations 

1. Information from this project was presented at the 

Diesel Engine Emission Reduction (DEER) 

Conference in Chicago, Illinois, in August 2005. 

References 

1. http://www.ott.doe.gov/decse/ 

2. U.S. Department of Energy, Engine Manufacturers 

Association, Manufacturers of Emission Controls 

Association, “Diesel Emission Control – Sulfur 

Effects (DECSE) Program – Phase I Interim Data 

Report No. 2: NOx Adsorber Catalysts,” October 

1999 

3. Webb C., Weber P., Thornton M., “Achieving Tier 2 

Bin 5 Emission Levels with a Medium Duty Diesel 

Pick-Up and a NOx Adsorber, Diesel Particulate 

Filter Emissions System—NOx Adsorber 

Management,” SAE Paper 2004-01-0585, March 

2004, Detroit, Michigan. 

4. Weber P., Webb C., Thornton M., “Achieving Tier 2 

Bin 5 Emission Levels with a Medium Duty Diesel 

Pick-Up and a NOx Adsorber, Diesel Particulate 

Filter Emissions System—Exhaust Gas Temperature 

Management,” SAE Paper 2004-01-0584, March 

2004, Detroit, Michigan. 

30 
Fuels Technologies FY 2005 Progress Report 

II.3 Fuel-Borne and Fuel-Derived Reductants for Diesel Exhaust NOx Reduction 

John F. Thomas (Primary Contact), Ron Graves, Brian West, Shean Huff 

Oak Ridge National Laboratory 

National Transportation Research Center 

2360 Cherahala Blvd. 

Knoxville, TN 38932 

DOE Team Lead: Stephen Goguen 

Objectives 

• Explore methodologies for forming and utilizing fuel-borne and fuel-derived reductants to enable 

lean-NOx catalysis systems for diesel engines with high effectiveness and low energy penalty. 

Approach 

• Use a novel in-cylinder fuel injection strategy to produce H2 under net-lean engine operation (leveraged 

with other research activities). 

• Run experiments with a lean-NOx catalyst to quantify any beneficial effects of such H2 production under 

lean conditions. 

Accomplishments 

• Efforts of previous years were embodied and published as an SAE paper. This work concerned broad 

performance mapping of a Ag-based catalyst, hydrocarbon selective catalytic reduction (HC-SCR) system 

(provided by Caterpillar, Inc.) under realistic conditions using 17 reductants. 

• A modest HC-SCR Work for Others (WFO) research project equally funded by ExxonMobil Research & 

Development and Caterpillar Inc. was performed during the second quarter of FY 2005. This work was 

enabled by the earlier Ag-based catalyst effort performed in cooperation with Caterpillar, Inc. New types 

of catalyst were evaluated in the course of this work. The results of the WFO project are not presented 

here. 

• Experiments were performed using a novel in-cylinder fuel injection strategy to produce H2 under net-lean 

engine operation. A demonstration experiment revealed that highly accelerated HC-SCR catalyst light-off 

is possible using this technique. 

Future Directions 

• Investigate the potential to produce useful fuel-derived reductants from compression-ignition fuels with 

and without fuel additives. 

• Experiment with selected reductant and catalyst combinations. 

• Continue to work with industry partners. 

• An open issue that could be addressed in the future is HC-SCR durability and robustness. This applies to 

Ag-based catalysts and other HC-SCR catalysts. 

Introduction reductant is introduced into the oxygen-rich exhaust 

which then passes over a catalyst, and NOx is 

One of the technology options for diesel exhaust selectively reduced to N2. To date, only urea SCR 

NOx emission control is selective catalytic reduction systems have adequate NOx control effectiveness to 

(SCR) with hydrocarbons or urea. With SCR, a be considered as viable emission control systems, but 

31 
Fuels Technologies

this requires development of an onboard filling and 

storage system for the reductant that is entirely 

separate from the fuel system. This also means a 

separate delivery, storage, and dispensing 

infrastructure would need to be deployed, 

presumably at fuel filling stations. For the fuel-borne 

or fuel-derived reductant concept, the reductant is 

part of the fuel or can be produced from the fuel. No 

separate onboard system and infrastructure would be 

required. 

Synthesis gas has been shown to be an effective 

reductant. Production of synthesis gas can be 

achieved with fuel reformers, but novel in-cylinder 

approaches may also produce similar species, in 

particular H2. A reported application of reformate 

gas, and specifically H2, is to enhance HC-SCR 

catalyst function [1-3]. Researchers have reported 

that H2 significantly improves NO conversion over 

Ag/Al2O3 catalysts across a wide temperature range 

[1-3]. 

Approach 

Previous efforts have been made to explore the 

in-cylinder production of reformate gas which 

includes significant H2. The basic effort for 

development of these methods was performed as part 

of the DOE Advanced Combustion Engine Program 

and is reported in the FY 2005 Progress Report for 

Advanced Combustion Engine R&D. One of these 

previously developed methods is known as the 

delayed extended main (DEM) fuel injection strategy 

[4]. As the name implies, the main fuel injection is 

delayed and extended to create rich conditions late in 

the cycle in order to produce H2. The approach used 

in this work is to apply a variation on the DEM 

strategy to enhance the effectiveness of HC-SCR. 

Results 

Fiscal year 2004 experimental efforts were 

devoted to performance mapping of a Ag-based 

HC-SCR catalyst provided by Caterpillar, Inc., 

which was designed to work well with ethanol as the 

reductant. In addition to ethanol, 16 reductants were 

tested under realistic conditions (exhaust from a 

5.9 liter diesel engine), with 1-propanol and 

1-butanol giving superior low-temperature results 

compared to ethanol. This FY 2004 work was 

 FY 2005 Progress Report 

embodied and published as an SAE paper in FY 

2005. As a direct result of this HC-SCR work, Oak 

Ridge National Laboratory (ORNL) was approached 

to perform a modest WFO research project equally 

funded by ExxonMobil Research & Development 

and Caterpillar, Inc. This R&D effort was performed 

during the second quarter of FY 2005. New types of 

HC-SCR catalyst were evaluated in the course of this 

work, but the results are as yet unpublished. 

Experiments using a 1.7 liter Mercedes-Benz 

diesel engine were performed to develop an incylinder fuel injection method which controls the 

combustion process such that reformate gas with 

significant H2 is generated while maintaining a lean 

air-fuel ratio in the bulk exhaust gas. By operating 

only 1 of 4 engine cylinders in the DEM mode at any 

given time, significant amounts of reformate rich in 

H2 can be generated while the bulk exhaust gases are 

oxygen rich. Which cylinder is operating in DEM 

mode can be changed in some pattern if desired to 

control wear and cylinder imbalance. This method of 

generating the H2 is referred to as the individualcylinder DEM strategy. It was demonstrated that 

exhaust containing up to 0.8% H2, over 1% CO, and 

3,000 ppm hydrocarbon (HC) with over 9% O2 

remaining could be produced. This reformate 

production strategy is reported with more detail in 

the FY 2005 Progress Report for Advanced 

Combustion Engine R&D. 

Leveraging the Advanced Combustion Engine 

Program effort, a preliminary catalyst experiment 

was conducted with a commercial platinum HC-SCR 

catalyst core supplied by Manufacturers of Emission 

Control Association to examine the ability of 

reformate gas to accelerate catalyst light-off. Figure 

1 shows a schematic of the experimental setup. 

Figure 1. Experimental Setup Schematic Diagram 

32 
Fuels Technologies FY 2005 Progress Report 

Figure 2. Catalyst Core Temperature-Time Trace for 

30k hr

-1 Space Velocity; Normal Lean Engine 

Operation Versus Individual-Cylinder DEM 

(lean with H2) 

Figure 3. Catalyst Inlet and Outlet NOx Concentration, 

and Catalyst Inlet, Core, and Outlet 

Temperatures for Individual-Cylinder DEM 

Strategy 

Figure 2 compares the results for core catalyst 

temperature rise with normal operation versus using 

the individual-cylinder DEM strategy. The flow 

rates through the catalyst sample were the same in 

each case, and the exhaust temperature at the turboout location for each case was about 280-290°C. 

Both curves show a small but very steep rise in 

temperature when the flow through the catalyst first 

begins (the pump is started) at about the 15-second 

point in Figure 2. The warmup rates are similar until 

the core temperature reaches about 100°C, at which 

time the augmented warmup begins to take effect. At 

about 120 seconds, the catalyst lights off, its core 

temperature rapidly jumping about 50°C, then 

continuing to rise to nearly 500°C, at which point the 

augmentation (DEM) is stopped. 

The augmented warmup is shown again in Figure 

3 (with a different time axis), including the catalyst 

inlet, core and outlet temperature as well as engineout (EO) and tailpipe (TP) NOx emissions. The 

light-off is seen at about 240 seconds in this figure. 

At this point, the core temperature exceeds that of the 

inlet temperature and continues to rise until the 

reformate production is aborted just before 400 s (as 

the core temperature approaches 500°C). The TP 

NOx is more than 100 ppm below the engine-out 

level, representing a 25% NOx reduction. Also note 

that the TP NOx remains lower even after normal 

combustion is resumed. Further experiments will be 

performed to determine if this phenomenon is 

repeatable. 

Conclusions 

• Operating 1 of 4 cylinders with a rich DEM 

strategy can produce a continuous stream of up 

to 0.8% H2, over 1% CO, and 3000 ppm HC in 

net lean exhaust with over 9% O2 remaining. 

• Preliminary catalyst experiments show that the 

presence of reformate in net-lean diesel exhaust 

can significantly accelerate catalyst light-off. 

• Specific promotion of catalytic NOx conversion 

by H2 during net lean operation has not been 

demonstrated. Future experiments are planned to 

explore this further on several catalyst 

formulations, in such a way that the hypothesis 

of NOx enhancement by H2 can be examined. 

Special Recognitions & Awards/Patents 

Issued 

1. Patent application filed entitled “Stripping Ethanol 

from Ethanol-Blended Fuels for Use in NOx SCR,” 

February 10, 2003. 

FY 2005 Publications/Presentations 

1. John F. Thomas, Bruce G. Bunting, Samuel A. Lewis, 

Sr., John M. Storey, Ron L. Graves, ORNL; 

Paul Park, Caterpillar, Inc., “Hydrocarbon Selective 

Catalytic Reduction Using a Silver-Alumina Catalyst 

with Light Alcohols and Other Reductants,” SAE 

Paper Number 2005-01-1082, presented at SAE 2005 

World Congress, Detroit, MI, April, 2005. 

33 
Fuels Technologies FY 2005 Progress Report 

2. John F. Thomas, Bruce G. Bunting, Samuel A. Lewis, 

Sr., John M. Storey, Ron L. Graves, ORNL; 

Paul Park, Caterpillar, Inc., “Silver Alumina Catalyst 

Performance with Light Alcohols and Other 

Reductants,” Proceedings: U.S. Department of 

Energy 10th Diesel Engine Emissions Reduction 

Conference, Coronado, California, August 29 to 

September 2, 2004. Paper sent April 2005, and is 

available on the web. 

References 

1. Shigeo Satokawa, Junji Shibata, Ken-ichi Shimizu, 

Atsushi Satsuma, Tadashi Hattori, “Promotion Effect 

of H2 on the Low Temperature Activity of the 

Selective Reduction of NO by Light Hydrocarbons 

over Ag/Al2O3,” Applied Catalysis B: 

Environmental, 2003, 42, 179-186. 

2. Junji Shibata, Yuu Takada, Akira Shichi, 

Shigeo Satokawa, Atsushi Satsuma, Tadashi Hattori, 

“Influence of Zeolite Support on Activity 

Enhancement by Addition of Hydrogen for SCR of 

NO by Propane over Ag-Zeolites,” Applied Catalysis 

B: Environmental, 2004, 54, 137-144. 

3. Robbie Burch, “Fundamental Aspects of Lean-Burn 

Hydrocarbon Selective Catalytic Reduction,” Queens 

University, Belfast, Cross-Cut Lean Exhaust 

Emissions Reduction Simulations (CLEERS), 

www.cleers.org (2004). 

4. Brian West, Shean Huff, James Parks, Sam Lewis, 

Jae-Soon Choi, William Partridge, John Storey, 

“Assessing Reductant Chemistry During In-Cylinder 

Regeneration of Diesel Lean NOx Traps,” SAE 

Transactions - Journal of Fuels & Lubricants 4, 2004, 

1975-1985, paper 2004-01-3023. 

34 
Fuels Technologies FY 2005 Progress Report 

II.4 Effectiveness and Sulfur Tolerance of Selective Catalytic Reduction and 

Diesel Particle Filter Systems 

Brian H. West 

Oak Ridge National Laboratory 

2360 Cherahala Boulevard 

Knoxville, TN 37932 

DOE Team Lead: Stephen Goguen 

Subcontractor: 

Southwest Research Institute, San Antonio, TX

Objectives 

• Demonstrate the low-emissions performance of advanced diesel engines operating on advanced fuels and 

equipped with low-pressure-loop exhaust gas recirculation (EGR) plus urea selective catalytic reduction 

(SCR) and diesel particulate filters (DPFs). 

• Evaluate the sensitivities of the emission controls to fuel variables. 

• Use a fuels matrix of five fuels, including four Diesel Emission Control Sulfur Effects (DECSE) fuels with 

sulfur levels of 3, 8, 15, and 30 ppm plus a refinery fuel of nominally 15 ppm sulfur, referred to as BP15. 

• Determine the regulated and unregulated emissions with and without emission controls. 

• Determine toxic and unregulated emissions levels. 

• Examine the durability of the emission control systems. 

Approach 

• Set up a heavy-duty engine in an emissions test cell to optimize emissions reduction performance of two 

different emission control systems (referred to as System A and System B) utilizing urea SCR. 

• Apply a low-pressure-loop EGR system to reduce engine-out NOx to ~ 2.0 - 2.5 g/hp-hr or less. 

• Add emission control system(s), DPFs and SCR systems with urea injection, to reduce tailpipe emissions 

of both NOx and particulate matter (PM). (Two different emission control systems – Systems A and B – 

both comprised of DPFs and SCR catalysts, will be evaluated.) 

• Integrate controls and optimize performance to reach the lowest possible emissions of NOx and PM for 

both systems. 

• Perform 6,000-hour durability tests simultaneously with Systems A and B, checking emissions – regulated 

and unregulated – at 2,000-hour intervals. 

Accomplishments 

• By the end of FY 2005, all experimental work had been completed. Both systems had accumulated 6,000 

hours of aging, and all emissions tests had been completed. 

• Southwest Research Institute presented their final report of the project and handed over all files and data 

necessary for the working group to complete the Advanced Petroleum-Based Fuels Diesel Emissions 

Control (APBF-DEC) final report. 

35 
Fuels Technologies FY 2005 Progress Report 

Future Directions 

• All work has been completed on this project, a draft report has been submitted, and the final report is being 

prepared. 

Introduction and Approach 

Southwest Research Institute (SwRI) was the 

subcontractor for this APBF-DEC project, and 

technical guidance was provided by the APBF-DEC 

working groups. Technical and programmatic 

oversight of the activities was accomplished with a 

technical team led by Oak Ridge National 

Laboratory, with an industry co-lead. Other team 

members represented automobile and engine 

manufacturers, suppliers, fuel and fuel additive 

companies, and government agencies. Caterpillar 

provided 12-liter engines for the project, and the 

Manufacturers of Emission Controls Association 

provided two exhaust emission control systems. 

Each emission control system included a diesel 

particulate filter combined with SCR catalysts. 

Low-pressure-loop EGR systems were provided by 

STT-EMTEC in Sweden, while Robert Bosch 

Company provided the urea injection systems. 

The plan was to optimize emissions performance 

with two different catalyst systems (Systems A and 

B, each comprised of DPF and urea SCR catalysts). 

After optimization, the emissions performance was 

characterized with four different fuels: DECSE fuel 

with sulfur levels of 3, 8, and 15 ppm plus a BP 

refinery fuel with nominally 15 ppm sulfur. A 

limited test was performed with DECSE 30 fuel 

(30 ppm sulfur). Emissions were thoroughly 

characterized for these tests, including unregulated 

emissions of interest plus toxic and unregulated 

emissions compounds. 

Following all the emissions tests with each 

system, the systems were set up in a test cell for 

aging the systems, where they underwent 6,000 hours 

of durability testing with emissions tests at the 

2,000-, 4,000-, and 6,000-hour points. 

Results 

Optimization of emission control systems for 

both Systems A and B was completed in FY 2004. 

Aging of both systems for 6,000 hours and final 

emissions tests were completed in June 2005. 

During the period of aging, the systems were taken 

back to the emissions test cell for full emissions 

testing with the fuels matrix at intervals of 2,000 

hours, 4,000 hours, and 6,000 hours each. The aging 

cycle was composed of repetitive ESC tests. 

At the start of the aging cycle, PM emissions 

were well controlled by both systems over the U.S. 

transient cycle below the 2007-2010 requirement of 

0.01 g/hp-hr. Very good control of PM throughout 

the aging period was maintained by both systems, 

and no problems with PM regeneration were 

encountered. That is, passive DPF regeneration 

occurred throughout the project and no active 

regeneration was needed. It is possible that this 

phenomenon is an artifact of the aging cycle used, 

and real-world operation may require some active 

control of DPF regeneration. Resolving this issue 

was beyond the scope of this project. The NOx level 

over the U.S. transient cycle at the start of aging was 

near the 2010 limit of 0.2 g/hp-hr for System A, but 

not as low for System B (~ 0.47 g/hp-hr). It should 

be noted that System B’s SCR catalyst was of smaller 

volume than was that for System A. Good control of 

NOx emissions was maintained by both systems over 

the aging cycle. 

With System A there was the appearance of a 

degradation of NOx control at the 2,000-hour test 

point over the transient emission test cycle. This 

result was later attributed to a phenomenon of urea 

overdosing during the aging cycle, and it was shown 

to be reversible with exposure to NOx. The presence 

of an ammonia sensor downstream of the catalyst 

system probably would have averted this problem. 

These phenomena with System A are not well 

understood at this time and were beyond the scope of 

research and of funding for this project to investigate 

thoroughly. Nevertheless, the results of the 

phenomena are evident in the figures to follow. 

System B demonstrated good maintenance of 

NOx control (over the transient test cycle) during the 

entire 6,000-hour aging test, albeit that the system 

36 
Fuels Technologies FY 2005 Progress Report 

Figure 1. NOx Emissions on the Transient Cycle – 

Systems A&B – DECSE 8 ppm Fuel – 

Composite Results 

Figure 3. PM Emissions on the Transient Cycle – 

Systems A&B – DECSE 8 ppm Fuel – 

Composite Results 

Figure 2. NOx Emissions on the Steady-State Cycle – 

Systems A&B – DECSE 8 ppm Fuel – 

Composite (Average 2 Cycles) 

Figure 4. PM Emissions on the Steady-State Cycle – 

Systems A&B – DECSE 8 ppm Fuel – 

Composite (Average 2 Cycles) 

did not control NOx to levels as low as with System 

A. NOx and PM emissions results for both systems 

over the 6,000 hours of aging and for both the U.S. 

transient cycle and ESC steady-state cycle are 

illustrated in Figures 1-4. 

Conclusions 

Major conclusions from the project are as 

follows: 

• Demonstrated the potential of low-pressure-loop 

EGR, diesel particulate filter, and urea SCR to 

achieve 2010 emissions levels for heavy-duty 

engines 

• Demonstrated that these technologies are not 

sensitive to fuel sulfur level in the 0-30 ppm 

range 

• Demonstrated the stability of emission control 

systems over 6,000 hours of operation (on the 

ESC cycle) 

• This project emphasized several issues important 

for commercialization of these technologies: 

– Importance of closed-loop control and of the 

need for integration of the emission control 

system and engine 

– Need to improve both the low-temperature 

conversion efficiency and the hightemperature catalyst efficiency and 

durability of SCR catalysts 

– Need to optimize boosting and EGR 

calibration to minimize fuel economy 

degradation 

– Need for ammonia sensors to be used in 

closed-loop controls 

37 
Fuels Technologies FY 2005 Progress Report 

– Need to examine long-term passive versus 

active regeneration of DPFs 

– Properly sizing the SCR catalyst to the 

engine so that the catalyst is large enough to 

effectively reduce NOx but not so large as to 

introduce large lags in both ammonia storage 

and NOx conversion

FY 2005 Publications/Presentations 

1. “Final Update on APBF-DEC EGR/DPF/SCR 

Demonstration Project at SwRI,” Chris Sharp and 

Magdi Khair, Southwest Research Institute, and 

Ralph McGill, Sentech, presented at the 2005 DEER 

Conference, Chicago, Illinois, August 2005 

38 
Fuels Technologies FY 2005 Progress Report 

II.5 Phosphorus Poisoning of Diesel Oxidation Catalysts 

Bruce G. Bunting (Primary Contact), Todd Toops, Sam Lewis, Karren More

Oak Ridge National Laboratory (ORNL)

2360 Cherahala Blvd.

Knoxville, TN 37932

Ke Nguyen and Scott Eaton 

University of Tennessee Knoxville 

DOE Team Lead: Stephen Goguen 

Subcontractor:

University of Tennessee, Knoxville, TN

Objectives 

• Develop techniques for measuring the physical and chemical state of phosphorus in engine exhaust and 

determine its effects on diesel aftertreatment performance. 

• Measure catalyst deactivation by phosphorus poisoning in accelerated tests and correlate to washcoat 

surface changes. 

• Correlate accelerated poisoning tests to long-term and catastrophic poisoning of catalysts that occurs in 

field service. 

Approach 

• Conduct literature search to determine key parameters associated with phosphorus poisoning and 

measurement techniques. 

• Design test rig and methodologies for exhaust chemistry measurement, catalyst poisoning and catalyst 

performance evaluation. 

• Conduct experimental investigations of accelerated phosphorus poisoning techniques and surface 

characterization. 

• Team with University of Tennessee at Knoxville in evaluating catalysts using a laboratory bench-flow 

reactor. 

Accomplishments 

• Compared characteristics of field service diesel oxidation catalysts with known deactivation mechanisms 

with similar catalysts poisoned by accelerated techniques. 

• Compared performance and materials characteristics between the two catalysts. 

• Evaluated exhaust phosphorus chemistry as a function of engine exhaust temperature and method of 

phosphorous introduction. 

Future Directions 

• Conduct further accelerated poisoning tests and measurements in order to better define phosphorus exhaust 

chemistry and resulting effects on catalyst performance. 

• Identify absorbed phosphorus compounds using surface analytical techniques for the comparison of field 

service and accelerated catalyst poisoning. 

39 
Fuels Technologies FY 2005 Progress Report 

• Apply techniques to new engine oil additives and catalyst materials and types, such as lean NOx traps 

(LNTs) and diesel particulate filter (DPF) catalysts. 

• Extend techniques to DPFs and expand project to include effects of ash and soot loading in addition to 

phosphorous poisoning. 

Introduction 

Phosphorus is a well-known catalyst poison that 

is derived from the zinc dialkyldithiophosphate 

(ZDDP) additive in lube oil used as an anti-wear 

agent. While in operation, an engine consumes lube 

oil, and this results in the subsequent presence of 

phosphorus in the exhaust gases. The form and 

amount of phosphorous varies based on engine 

operating conditions. Phosphorus in the exhaust 

reacts with catalysts and causes a loss of performance 

through masking or chemisorption. Although the 

amount of ZDDP in lube oil is currently being 

reduced, a minimum amount appears to be necessary 

for adequate engine durability. Ways of reducing the 

effects of exhaust phosphorus on catalyst 

performance include reducing the amount of 

phosphorous, altering the chemical state of the 

phosphorus to a less damaging form, or formulating 

catalysts more resistant to phosphorous poisoning. 

To evaluate these solutions, it is necessary to 

measure the chemical state and compounds of 

phosphorus in diesel exhaust and the resulting 

changes in catalyst performance and material 

properties. Accelerated evaluation protocols allow 

such development to proceed more rapidly. 

Approach 

A 517cc Hatz single-cylinder diesel engine 

bench was utilized to provide a variety of pathways 

through which phosphorus can be introduced into the 

exhaust gases. The engine was modified to 

accommodate accelerated poisoning techniques 

including intake manifold injection, fuel doping, 

exhaust manifold injection and lube oil doping to 

simulate different engine and usage situations. 

A photograph of the engine bench is shown in 

Figure 1. Fresh commercial catalyst samples were 

compared to field service bus catalysts. Exhaust 

gases were collected during the experiment for each 

poisoning technique and analyzed using electrospray 

mass spectroscopy to determine the phosphorus 

species formed. 

Figure 1. Photograph of engine bench used for 

accelerated poisoning and light-off evaluation 

of diesel oxidation catalysts. 

Hydrocarbon and carbon monoxide oxidation 

light-off performance was measured using the engine 

bench for both the field and engine bench-poisoned 

catalysts. Samples were then sectioned and prepared 

for material characterization by X-ray fluorescence 

spectroscopy (XRF), X-ray photoelectron 

spectroscopy (XPS), and electron probe 

microanalysis (EPMA). In addition, bench-flow 

reactor tests were used to obtain hydrocarbon and 

carbon monoxide light-off performance from 

samples cored from field service and enginepoisoned catalysts. The bench-flow reactor was used 

to provide evaluation under more controlled 

conditions than the engine bench allowed. 

Results 

Commercial catalysts of similar formulation to 

the field service catalysts were poisoned using 

accelerated intake manifold injection of ZDDPdoped lube oil. The amount of phosphorus present in 

the injected lube oil was 0.5 grams P/50 cc oil. This 

correlates to 700 times normal phosphorous 

40 
Fuels Technologies

accumulation rate for a heavy-duty truck, when 

combined with the accelerated consumption rate 

used. Accelerated poisoning tests were conducted at 

different engine exhaust temperatures, and exhaust 

gas samples were collected during poisoning using 

an impinger. Catalyst temperatures for these tests 

were maintained at 165°C, 280°C and 420°C. 

Electrospray mass spectrometry was used to analyze 

exhaust gas species, and the results indicated that the 

ZDDP was completely combusted in the engine. The 

resulting chemical species derived from the ZDDP 

were phosphoric acid (H3PO4) and zinc sulfate 

(ZnSO4). After poisoning, catalysts were sectioned 

and underwent materials characterization for 

comparison to the field service catalysts. 

XRF analysis revealed that phosphorus and 

sulfur deposition was higher at higher catalyst 

temperatures. XRF results are listed in Table 1 and 

indicate that a maximum of 54% of the total 

phosphorus and 25% of the total sulfur were 

deposited in the catalyst during the accelerated 

poisoning. The maximum deposition found in the 

accelerated poisoning tests was 3.22 grams P and 

4.57 grams S, which was of the same order as the 

field service catalysts. EPMA analysis performed at 

the ORNL High Temperature Materials Laboratory 

and the University of Tennessee confirmed the 

presence of phosphorus and sulfur and revealed that 

phosphorus was preferentially deposited at the front 

section of the catalyst while sulfur was evenly 

distributed along the catalyst length. Phosphorus 

concentrations were found to be greatest at the 

catalyst surface with a steep concentration gradient 

along the washcoat depth, and sulfur was found to 

Table 1. Effect of catalyst temperature on phosphorus, 

sulfur and zinc (weight percent) deposited on 

engine-poisoned diesel oxidation catalysts by 

intake manifold injection as measured by XRF. 

Temperature 

(°C) 

Phosphorus 

Deposition 

(%) 

Sulfur 

Deposition 

(%) 

Zinc 

Deposition 

(%) 

165 26.60 6.67 1.79 

280 46.20 12.94 8.07 

420 53.67 25.40 2.50 

 FY 2005 Progress Report 

disperse evenly throughout the washcoat. These 

findings were in agreement with analysis conducted 

on field service catalysts. Sample EPMA X-ray 

maps and line scan are shown in Figures 2 and 3, 

respectively. Catalyst samples are being further 

analyzed using XPS to identify phosphorus 

compounds deposited on the catalysts. 

Hydrocarbon and CO light-off performance 

measurement was conducted using the engine bench 

at the National Transportation Research Center and 

the bench-flow reactor at UT for both the accelerated 

poisoning catalysts and the field service catalysts. 

For accelerated poisoning catalysts, light-off 

temperatures increase between 50°C and 100°C, 

showing significant loss of performance. 

Comparable loss in performance was found for the 

field service catalysts. Figure 4 shows the effects of 

phosphorus loading and deactivation methods on CO 

conversion for the engine-bench evaluation. 

Conclusions 

• Phosphorus and zinc chemistry is not dependent 

on engine load or exhaust temperature for 

accelerated intake manifold injection. 

– Phosphorus in the exhaust gases prior to the 

catalyst was found as phosphoric acid and 

adsorbed on the catalyst along with sulfur. 

– Zinc formed ZnSO4 compounds, which 

passed through the catalysts with only minor 

adsorption. 

• Higher exhaust temperatures during accelerated 

intake manifold injection poisoning result in 

more phosphorus deposition. 

• Phosphorus compounds deposit preferentially on 

the front sections of both field service and 

accelerated poisoning catalysts, with similar 

phosphorus surface concentrations and washcoat 

penetration depths. 

• Sulfur compounds deposit uniformly within the 

washcoat and along the catalyst length in both 

field service and accelerated poisoning catalysts, 

with more deposition on field service catalysts. 

• Negligible zinc concentrations are found in both 

field service and accelerated poisoning catalysts. 

41 
Hydrocarbon and CO light-off temperatures are similar for field service and accelerated poisoning 

catalysts. 

Fuels Technologies FY 2005 Progress Report 

• (a) 

(b) 

(c) 

Figure 2. (a) EPMA backscatter image of the front section of a fresh commercial diesel oxidation catalyst. (b) EPMA 

backscatter and X-ray maps of the front section of a field service catalyst with phosphorus and sulfur 

deposition. (c) EPMA backscatter and X-ray maps of the front section of a bench-poisoned catalyst (poisoned 

via intake manifold injection) with phosphorus and sulfur deposition. 

Figure 3. EPMA line-scan of the front section of a field service catalyst detailing elemental concentrations as a function 

of washcoat depth. 

42 
Fuels Technologies FY 2005 Progress Report 

Figure 4. Engine-bench evaluation of carbon monoxide conversion of fresh commercial catalyst, intake manifold 

injection poisoned commercial catalysts and field service catalysts. 

FY 2005 Publications/Presentations 3. Bunting, B.G., More, K., Lewis, S., Toops, T., 

1. Bunting, B.G., More, K., Lewis, S., and Toops, T., 

“Phosphorous Poisoning and Phosphorous Exhaust 

Chemistry with Diesel Oxidation Catalysts”, SAE 

2005-01-1758. 

2. Bunting, B.G. and Nguyen, K., “The Development 

of Rapid Aging and Poisoning Protocols for the 

Verification of Combustion Engine Aftertreatment 

Devices”, 2005 Vietnam International Conference 

on Automotive Technology for Vietnam, 10/05, 

paper 007. 

Eaton, S., and Nguyen, K., “Transportation, Fate, and 

Impact of Lube Oil Phosphorous”, DOE 2005 Fuels 

Technology Program Merit Review, 3/05. 

43 
Fuels Technologies FY 2005 Progress Report 

II.6 Rapid Aging of Lean NOx Traps (LNTs) 

Bruce G. Bunting (Primary Contact) and Todd Toops 

Oak Ridge National Laboratory 

2360 Cherahala Blvd. 

Knoxville, TN 37932 

Ke Nguyen, Hakyong Kim and Ajit Gopinath 

University of Tennessee at Knoxville 

DOE Team Lead: Stephen Goguen 

Subcontractor:

University of Tennessee, Knoxville, TN 37996-2210

Objectives 

• Develop protocols for rapid thermal aging of lean NOx traps (LNTs) to be used with a bench-flow reactor 

and an engine bench. 

• Perform rapid thermal aging on various LNTs using bench-flow reactor. 

• Extract deactivation kinetics from experimental results and formulate a simple theoretical model of 

thermal aging of LNTs. 

• Compare bench-flow reactor-aged LNTs to engine bench-aged and field-aged LNTs. 

Approach 

• Conduct literature search for the LNT thermal deactivation mechanisms. 

• Select appropriate surface characterization techniques. 

• Perform rapid thermal aging experiments on LNT samples using bench-flow reactor and small engine 

bench. 

• Perform surface characterization techniques such as transmission electron microscopy (TEM), X-ray 

diffraction (XRD), and electron probe microanalysis (EPMA) to characterize the microstructure changes 

of LNT washcoat. 

Accomplishments 

• Established protocols for rapid thermal aging experiments for both bench-flow reactor and engine bench. 

• Performed rapid thermal aging on LNTs at aging temperatures of 900 and 1000°C using the bench-flow 

reactor. 

• Performed TEM, XRD, and EPMA studies on fresh and bench-flow reactor-aged LNTs. 

• Observed the migration and accumulation of potassium at the interface of the washcoat and the cordierite 

substrate in aged high-temperature LNTs. 

• Observed sintering of precious metal in all LNTs evaluated at high temperatures. 

Future Directions 

• Perform thermal aging at several different lean/rich aging cycles at 900 and 1000°C to validate 

repeatability of data and to provide more samples for surface studies. 

• Perform additional thermal aging at 600, 700 and 800°C. 

44 
Fuels Technologies FY 2005 Progress Report 

• Conduct TEM, XRD and EPMA to obtain the progression of K migration away from the washcoat, the 

transformation of BaCO3 into other barium-mixed oxides, and sintering of the precious metal group 

(PGM). 

• Incorporate experimental results into the theoretical model for predicting the thermal degradation of LNTs. 

• Discuss results with catalyst suppliers to verify procedures and validity of data. 

• Compare results to field-aged catalysts to verify mechanisms and to establish accelerated severity factors. 

Introduction 

The LNT is formulated with NOx storage 

components or trapping materials, usually alkali or 

alkaline earth metals such as barium, potassium, 

sodium and cesium, and precious metals such as Pt 

dispersed over a high-surface-area γ-alumina 

washcoat. During the period of lean operation, NOx 

in the exhaust gas stream is stored in the storage 

components in the form of nitrates. During the 

shorter period of rich operation, the stored nitrates 

are decomposed to NOx, which is subsequently 

reduced to N2 by CO, H2 and unburned hydrocarbons 

over the PGM. In order to be effective in reducing 

NOx emissions, a LNT has to be subjected to 

periodic regeneration and desulfurization. Since 

these two processes are carried out under fuel-rich 

conditions, high-temperature excursions can be 

produced which can lead to deactivation of the LNT. 

Three potential thermal aging mechanisms which 

lead to the deactivation of the LNT have been 

identified: (i) the loss of dispersion of the PGM and 

the NOx trapping materials, (ii) interactions between 

the trapping materials and the γ-Al2O3 to form less 

efficient NOx storage components, and (iii) the loss 

of surface area or porosity of the storage components 

and the washcoat. An understanding of these thermal 

aging mechanisms is critical in developing better 

LNT washcoat formulations as well as theoretical 

models of thermal aging of LNTs. Consequently, the 

objectives of the present study are to develop 

protocols for rapid aging of LNTs using a bench-flow 

reactor and a small engine and to determine the 

thermal aging mechanisms and the deactivation rates 

as a function of aging temperature and time for 

several LNT catalysts. 

Approach 

In the present study, the thermal aging of two 

LNTs was investigated by lean-rich cycling at 

elevated temperatures using a bench-flow reactor 

Figure 1. Schematic of Bench-Flow Reactor 

system as shown in Figure 1. The use of the benchflow reactor allows precise control of the aging 

temperatures, the composition of the exhaust gases, 

and the duration of the rich and lean pulses. 

Simulated exhaust gas with a composition similar to 

the exhaust gas from a diesel engine is introduced 

into the bench-flow reactor system by means of mass 

flow controllers. Water vapor is introduced into the 

system via the steam generator. By activating 

solenoid valves, lean and rich cycles of any duration 

can be achieved, and by adjusting the duration of rich 

cycle and the fuel (CO+H2) to air ratio, it is possible 

to produce a range of aging temperatures inside the 

LNT sample. Prior to thermal aging, all LNTs were 

de-greened in a flowing environment of air and water 

vapor. The NOx conversion of the degreened LNTs 

was then evaluated at 400°C prior to aging. For 

thermal aging, the LNTs were subjected to two 

different aging temperatures of 900 and 1000°C in a 

number of pre-determined cycles. The thermal aging 

of LNTs was carried out with the bench reactor 

maintained at 400°C using a cycle of 130 seconds 

lean and 50 seconds rich. At a given aging 

temperature, the NOx conversions were measured at 

regular intervals in order to investigate the effect of 

45 
Fuels Technologies

lean/rich aging cycles on the thermal aging. 

All bench-flow thermal aging and performance 

evaluations of LNTs were carried out at a NOx 

concentration of 1000 ppm and a gas hourly space 

velocity of 60,000 hr

-1 to match engine bench 

conditions. The LNT performance deterioration as 

a function of aging temperature and number of lean/ 

rich aging cycles and time was then obtained. 

To determine the effect of thermal aging on the 

growth of Pt crystallites, NOx storage sites and 

γ-Al2O3, washcoat powder was extracted from fresh 

and aged catalysts and analyzed by TEM, XRD, and 

EPMA. It is anticipated that the experimental results 

from the study can be used to determine the 

temperature range for the deactivation of LNTs by 

various thermal aging mechanisms, to correlate 

bench flow-aged catalysts to field-aged catalysts, and 

to extract deactivation kinetics from which 

theoretical models of thermal aging of LNTs can be 

formulated. 

Results 

Prior to the thermal aging experiments, the NOx 

conversion at different temperatures of the two fresh 

LNT catalysts was evaluated under lean/rich 

modulations with 20 s lean and 4 s rich. The LNT 

catalyst with a maximum NOx conversion at 350°C 

is referred to as the low-temperature LNT, whereas 

the other catalyst, with a maximum NOx conversion 

at 400°C, is referred to as the high-temperature LNT. 

The effect of aging temperature and lean/rich 

aging cycles on the NOx conversion of the two LNTs 

is shown in Figure 2. As can be seen in the figure, a 

common feature of the thermal deactivation curves is 

that after an initial decrease, the NOx conversion 

begins to level out as the number of lean/rich aging 

cycles increases. In addition, the NOx conversion of 

the two LNT formulations was affected differently 

by the thermal aging. At an aging temperature of 

900°C, the NOx conversion of the low-temperature 

LNT initially degrades at the same rate as that of the 

high-temperature LNT. As the number of lean/rich 

aging cycles increases, the NOx conversion of the 

high-temperature LNT appears to be stabilized while 

that of the low-temperature LNT is not stable. At an 

aging temperature of 1000°C, the low-temperature 

LNT degrades more severely than the high­

 FY 2005 Progress Report 

Figure 2. Effect of Aging Temperature and Aging Cycles 

on NOx Conversion of Low- and HighTemperature LNTs at a Gas Hourly Space 

Velocity of 60,000 hr

-1 

temperature LNT. The difference in thermal 

degradation characteristics can be attributed to the 

different compositions of the NOx trapping materials 

in the washcoats of the two LNTs. 

Figures 3a and 3b show typical TEM images 

obtained from the powder of fresh and aged hightemperature LNTs, respectively. The dark, relatively 

round objects in these images are Pt particles. Both 

images display a rather wide distribution of Pt 

particle sizes. The sintering effect is clearly seen in 

Figure 3b for the high-temperature LNT aged at 

900°C for 150 lean/rich aging cycles, in agreement 

with the XRD results (see Table 1). 

Figures 4a and 4b show the region 2θ = 15-85° 

of XRD spectra of fresh and aged high-temperature 

LNTs. Only the crystallite dimensions of Pt, γ-Al2O3 

and BaCO3 are evaluated from the full-width at halfmaximum of the peaks in the XRD spectra of the 

fresh and aged high-temperature LNTs, and the 

results are listed in Table 1. The characteristic 

spectral lines of CeO2, denoted as (•), at 2θ = 28.5, 

33.3, 47.5 and 56.4° are observed in both samples. 

On the other hand, only a faint spectral line of CeO3 

at 2θ = 30.6°, denoted as (ο), is observed in the fresh 

LNT sample, and none is observed in the aged 

sample. The spectral line at 2θ = 29.41°, denoted as 

(♦), is assigned to cerium mixed oxide, the 

composition of which has not been identified in the 

present study. Diffraction peaks corresponding to Pt, 

BaCO3 and γ-Al2O3 were detected for both fresh and 

46 
Fuels Technologies FY 2005 Progress Report 

(a) (b) 

Figure 3. TEM Images of Pt Particles (a) Fresh High-Temperature LNT (100,000X Magnification) and (b) HighTemperature LNT Aged at 900°C (100,000X Magnification) 

(a) (b) 

Figure 4. XRD Spectra of (a) Fresh High-Temperature LNT and (b) High-Temperature LNT Aged at 1000°C 

aged high-temperature LNTs. The average diameter 

of Pt crystallites in the fresh LNTs is not determined 

due to low peak intensities. The spectrum of the 

high-temperature LNT aged at 1000°C displays 

several remarkable differences with respect to that of 

the fresh sample. The diffraction peak of Pt at 

2θ = 39.8° becomes more discernable and intense 

and clearly indicates that the sintering of the Pt 

particles is due to the thermal aging. As seen in 

Table 1, the average Pt particle diameter increases 

from <2 to 12.5 nm on aging for the hightemperature LNTs subjected to 250 lean/rich aging 

cycles at 1000°C. However, the most notable result 

is the disappearance of the BaCO3 peaks at 2θ = 24.5 

and 42.1° at an aging temperature of 1000°C, not just 

for the high-temperature LNTs but for the lowtemperature LNTs as well (see Table 1). This may 

be due to the transformation of BaCO3 into a mixed 

oxide such as spinel-BaAl2O4, which is less efficient 

for NOx storage. Accordingly, further XRD and 

XPS analyses will be carried out in future studies to 

identify the exact composition of the newly formed 

barium mixed oxides. 

To investigate the migration and accumulation of 

alkali metal trapping materials, EPMA images of 

fresh and 900°C-aged high-temperature LNTs were 

obtained. As seen in Figures 5a and 5b, Ba and K 

were well dispersed in the washcoat of fresh hightemperature LNTs, shown as bright spots in the 

EPMA image, and there was no evidence of either 

barium or potassium presence in the cordierite 

47 
Fuels Technologies FY 2005 Progress Report 

Table 1. Average Diameter of Pt, BaCO3, and γ-Al2O3 Determined from XRD for Fresh and Aged Low-Temperature 

and High-Temperature LNTs 

XRD Sample Element and 

Compound 

P.D.(nm) XRD Sample Element and 

Compound 

P.D.(nm) 

Fresh Pt No Discernable Fresh BaCO3 24.32 

Low-Temperature Peak High-Temperature 

LNT 

BaCO3 13.71 

LNT 

BaCO3 24.32 

γ-Al

2O3 5.63 γ-Al2O3 7.87 

Low-Temperature LNT 

Aged at 900C 

Pt 8.19 High-Temperature LNT 

Aged at 900C 

Pt 9.83 

BaCO3 No Discernable 

Peak 

BaCO3 21.34 

γ-Al

2O3 5.76 γ-Al2O3 5.60 

Low-Temperature LNT 

Aged at 1000C 

Pt 14.68 High-Temperature LNT 

Aged at 1000C 

Pt 12.49 

BaCO3 No Discernable 

Peak 

BaCO3 No Discernable 

Peak 

γ-Al

2O3 7.26 γ-Al2O3 6.18 

(a) (b) 

Figure 5. EPMA Images of Barium Compounds (a) Fresh High-Temperature LNT and (b) High-Temperature LNT Aged 

at 900°C 

48 
Fuels Technologies FY 2005 Progress Report 

(a) (b) 

Figure 6. EPMA Images of Potassium Compounds 

(a) Fresh High-Temperature LNT and (b) High-Temperature LNT Aged at 900°C 

substrate. The Ba map in Figure 6a shows that the 

Ba crystallite size has been increased even though Ba 

was still well dispersed in the washcoat for the hightemperature LNTs subjected to 150 lean/rich aging 

cycles at 900°C. On the other hand, a significant 

amount of K originally in the washcoat migrated 

away from the washcoat and accumulated at the 

interface of the washcoat and the cordierite substrate, 

while the remaining K appeared as larger size 

particles in the washcoat, as evidenced in Figure 6b. 

Consequently, the sintering and the transformation of 

Ba and the migration of K into the cordierite 

substrate are the dominant mechanisms of thermal 

deactivation of alkali metal-supported LNTs. 

Preliminary results from EPMA clearly demonstrate 

that the loss of NOx conversion due to thermal aging 

can be minimized by suppressing the migration of K 

into the substrate. 

Conclusions 

• The thermal degradation of low-temperature and 

high-temperature LNTs increases as the aging 

temperature and the number of lean/rich aging 

cycles increase. 

• Low-temperature LNTs are degraded more 

severely than high-temperature LNTs. 

• The thermal degradation of LNTs can be 

attributed to: 

– The sintering of Pt particles and γ-Al2O3 

crystallites 

– The transformation of BaCO3 into less 

efficient NOx storage barium mixed oxides 

– The migration of K away from the washcoat 

and accumulation on the cordierite substrate 

in high-temperature LNTs 

Publications and Presentations 

1. Bunting, B.G. and Nguyen, K., “The Development of 

Rapid Aging and Poisoning Protocols for the 

Verification of Combustion Engine Aftertreatment 

Devices”, Vietnam SAE International Conference on 

Automotive Technology, paper 007, October 2005. 

2. Bunting, Toops, More, Nguyen, and Gopinath, 

“Rapid Aging of Lean NOx Traps for Diesel 

Applications”, 2005 DOE Fuels Program Peer 

Review, March 2005. 

49 
Fuels Technologies FY 2005 Progress Report 

II.7 Ultra-Low Sulfur Reduction Emission Control Device 

Ronald Rohrbach (Primary Contact), Gary Zulauf 

Honeywell Laboratories 

3660 Technology Drive 

Minneapolis, MN 54418 

DOE Team Lead: Stephen Goguen 

NETL Project Manager: Ralph Nine 

Subcontractors 

Mack Trucks, Inc., Hagerstown, MD 

Johnson Matthey, Malvern, PA 

Marathon Ashland Petroleum, Catlettsburg, KY 

American Wastes Industries, Maywood, IL 

Objectives 

To develop and demonstrate proof-of-concept for an “on-vehicle” desulfurization fuel filter for heavy- and 

light-duty diesel engines. 

• Define the most relevant chemistries available that would be suitable for sulfur reduction. 

• Modify the most promising chemistries to the requirements for the system. 

• Demonstrate the efficacy on an engine test. 

Approach 

• Phase I: Develop a concept design and analysis, and resolve technical barriers concerning removal of 

sulfur-containing species in low-sulfur fuels. 

• Phase II: Implement high-throughput screening techniques for chemistry selection and dynamic testing. 

• Phase III: Prototype design and testing; adapt research concept into a practical filter module and test its 

efficacy; produce prototype(s). 

• Phase IV: Life cycle studies; study life cycle and regeneration options for spent filters. 

• Phase V: Validation testing; conduct engine testing with NOx adsorber and test prototype filter on a 

heavy-duty diesel engine for efficacy; complete system testing and component integration. 

Accomplishments 

• Successfully completed Phases I, II, III and IV. Awaiting completion of the engine test in Phase V. 

The project has been delayed due to scheduling issues with the engine test at Mack Trucks. 

• From over 4,000 candidate chemistries tested for sulfur removal, one approach was chosen to go forward 

with. 

• Successfully demonstrated continuous sulfur removal at the 1 gallon scale. 

• Studied the fuel sensitivity of the sorbent and identified key components in the fuel which affect the 

sorbent’s performance. 

• Completed construction of a 10 gallon vessel for the engine demonstration. 

• Studied various fuel lubricants and characterized the loss of lubricity of the fuel after sulfur removal. 

50 
Fuels Technologies FY 2005 Progress Report 

• Characterized the mechanism of action of the sorbent to remove sulfur and identified key operational 

factors. 

• Began the optimization of the sorbent to improve its capacity, which will result in lower overall volume. 

• Screened available ultra-low sulfur diesel (ULSD) fuels. 

• Identified a new sorbent with 20% greater capacity and the potential to achieve a 3 gallon footprint. 

Future Directions 

• Complete the optimization of the sorbent to achieve a lower bed volume. 

• Integrate the NOx adsorber into the Mack engine and have it operate successfully. 

• Carry out the Mack engine validation. 

• Continue to screen sorbents for the new approach in order to meet the criteria. 

• Compile the final report. 

Introduction 

The goal of this project is to develop an emission 

control device that can enable engine manufacturers 

to comply with the new Environmental Protection 

Agency (EPA) emission standards, including Tier II 

Bin 5 for light-duty engines and the new '2007 Rule' 

for heavy-duty diesel engines. The '2007 Rule' 

includes a new diesel fuel sulfur limit that has a 

maximum cap of 15 ppm. Successful integration of 

the sulfur removal component into a heavy-duty 

diesel vehicle coupled with a post-combustion NOx 

adsorber catalyst device will, by default, be 

applicable to light-duty diesel engines. 

The sulfur removal device developed by this 

project can expedite implementation of the new 

emissions standards by reducing the need for diesel 

fuels to attain the ultra-low sulfur levels required to 

ensure optimal performance of NOx adsorber 

technologies under development. This should be 

accomplished at relatively modest cost to the enduser because the sulfur removal device will be an 

add-on to the existing fuel system and will be 

packaged in a conventional engineering format. 

It is anticipated that the cost of the proposed sulfur 

removal device to the consumer will represent no 

more than a low multiple of the current cost of a 

standard fuel filter. 

Approach 

Since the end of the last reporting period we have 

down-selected a single sorbent for engine testing. 

It has the highest sulfur removing capacity of over 

4,000 candidate reagents we have studied during this 

project. It is a commercially produced material of 

modest cost and with properties attractive for 

building a commercial product. It does not suffer 

from any health, safety, or environmental issues and 

its disposal, if that is the ultimate fate, will be not 

unlike that of the other components of traditional fuel 

filters. These factors and its high sulfur absorbance 

capacity have made it the sorbent of choice for 

proceeding with the project. 

Results 

Fuel Sensitivity 

Throughout this project we have been testing 

various ULSD fuels for their ability to be 

desulfurized using our sorbent. These fuels have 

shown a range of sulfur levels from 4.5 to 9 ppm. 

Figure 1 shows the range in performance of the sulfur 

sorbent with these ULSD fuels. The Chevron 

Texaco fuel will be the fuel which Mack will use in 

the engine test. Two samples of this fuel have been 

obtained, and their sulfur removal profiles are 

described in this figure. 

 In order to determine what properties in the fuel 

are controlling this variation, the aromatics content 

was measured and is presented in Figure 2. As can 

be seen, the lower the levels of higher polynuclear 

aromatics, the better the sulfur performance. This is 

consistent with the competitive binding that we have 

measured in the past for both 1-ring and 2-ring 

aromatics. These components in the fuel, which are 

at higher levels compared to the sulfur, compete for 

the same sites on the sorbent. 

51 
Fuels Technologies FY 2005 Progress Report 

Figure 1. Fuel Sensitivity 

Figure 2. Distributions of Aromatics in Various Fuels 

The sulfur distribution was measured for the 

Chevron Texaco fuel and compared to that of the BP 

fuel (Figure 3). As can be seen, the Chevron Texaco 

fuel has lighter sulfur components but also has the 

higher molecular weight sulfur species like the BP 

fuel. The BP fuel which we are testing here is over 1 

year old, and since then a cleaner fuel more like the 

Chevron Texaco fuel is available. 

Lubricity Loss 

From our earlier studies on fuel properties, we 

had seen a decrease in the fuel lubricity after passing 

through the sulfur adsorber. The reduction in 

lubricity was to a value below specification for the 

fuel. We now confirm this to be an issue even in 

column testing and at all stages in the life of the 

sulfur adsorbent. Either the sulfur which is being 

removed during the desulfurization is responsible for 

Figure 3. Sulfur Speciation 

52 
Fuels Technologies FY 2005 Progress Report 

Table 1. Fuel Properties 

Chemistry Notebook 

Ref 

Copper 

Corrosion 

D130 

Viscosity 

@40C 

D445 (cSt) 

Cetane 

No. D613 

Bromine 

No. D1159 

Cloud 

Point 

D2500 

(deg C) 

Total 

Aromatics 

in Diesel 

D5186 

(mass %) 

Mono 

Aromatics 

(mass %) 

Poly 

Aromatics 

(mass %) 

Lubricity 

D6079 

(mm) 

Thermal 

Stability 

D6468 (%) 

Control 

(BP ECD1) 

40065-13 1A 2.446 55.6 0.4 -6 23.3 20.7 2.6 0.465 98 

Sorbent A 40059-24 1A 2.451 50.5 0.41 -6 22.9 20.4 2.5 0.625 100 

Figure 4. Performance Comparison of Scale-Up 

the lubricity loss or the added lubricant is being 

removed by the sorbent. Table 1 shows the 

properties of the fuel before and after desulfurization. 

Scale-up 

The final stage of this project involves the scaleup of the sorbent. A prototype engineering design of 

the filter has been completed and the temperature 

control installed with a volume of 10 gallons. We 

have found that the scale-up performance from the 

25 mg to 1 gallon size has been consistent (see 

Figure 4). This closeness in performance after a 

scale transition of this magnitude gives us confidence 

that at the 10 gallon size it will function similarly. 

Sorbent Screening 

We are continuing to both optimize the sorbent 

as well as search for better sorbents in order to 

improve the sulfur removal capacity, which will lead 

to a smaller bed size. Figure 5 contains data on some 

promising new sorbents. As can be seen from Figure 

5, we have a new sorbent which yields a 20% 

improvement in sulfur removal performance. We are 

Figure 5. Sorbent Screening 

working with the vendor to try to further improve 

this and some other sorbents. We will still use our 

previous best candidate sorbent for the Mack engine 

test due to the overwhelmingly larger amount of 

experience we have with it. 

Conclusions 

• An approach to polish the sulfur from ULSD 

fuels has been identified. All the components 

necessary for the engine test are complete. 

• A unique sorbent has demonstrated the greatest 

promise to reduce sulfur in diesel fuel for this 

application. 

• The sorbent has been optimized to remove any 

external or internal diffusional barriers. 

• A successful large-scale activation procedure has 

been developed which is reproducible. 

• Successful scale-up of sulfur sorbent from 25 mg 

to 1 gallon has been achieved. 

53 
Fuels Technologies FY 2005 Progress Report 

• The sorbent removes lubricant from fuel, FY 2005 Publications/Presentations 

resulting in a loss of lubricity, requiring 1. “Diesel Desulfurization Filter”, 11th Annual Diesel readditization of lubricant. Engine Emission Reduction (DEER) Conference, 

• The source of fuel sensitivity of the sorbent has Chicago, Illinois, August 22, 2005. 

been identified as the presence of higher 

polynuclear hydrocarbons. 

• The operation of the sorbent has been elucidated. 

• Progress has been made on improving the 

sorbent’s sulfur capacity and lowering its 

footprint, but more work is necessary to achieve 

a <3 gallon size. 

54 
Fuels Technologies FY 2005 Progress Report 

II.8 Fuel and Emission Control System Effects on Unregulated Emissions 

John M. E. Storey (Primary Contact), Samuel A. Lewis, Sr., Linda A. Lewis 

Oak Ridge National Laboratory at NTRC 

P.O. Box 2008, MS 6472 

Oak Ridge, TN 37831-6472 

DOE Technology Development Manager: Kevin Stork 

Subcontractors: 

Southwest Research Institute, San Antonio, TX 

Desert Research Institute, Reno, NV 

Objectives 

• Develop and/or specify analytical methods for the determination of unregulated emissions specific to 

advanced diesel aftertreatment systems 

• Quantify unregulated emissions from Advanced Petroleum Based Fuels – Diesel Emissions Control 

(APBF-DEC) projects collected over transient and steady-state cycles 

Approach 

• Convene advisory group to decide on test protocols and methods for unregulated emissions measurement 

• Develop sampling and analytical methods for urea decomposition products 

• Develop sampling and analytical methods for nitroxy-alkane products 

• Analyze samples from APBF-DEC engine/aftertreatment projects 

Accomplishments 

• Completed unregulated emissions sampling and analysis for the APBF-DEC heavy-duty selective catalytic 

reduction (SCR) project 

• Completed unregulated emissions sampling and analysis for the APBF-DEC pickup/SUV NOx adsorber 

catalyst (NAC) project 

• Completed unregulated emissions sampling and analysis for the APBF-DEC light-duty NAC project 

Future Directions 

• Complete unregulated emissions summary reports for each of the APBF-DEC project reports 

• Complete final report on all APBF-DEC unregulated emissions activities including methods development 

Introduction 

The APBF-DEC Toxics and Unregulated 

Emissions team was formed to address issues and 

provide guidance to the APBF-DEC project teams 

on toxics and unregulated emissions measurement. 

It was recognized that urea-SCR and NOx adsorber 

systems can produce byproducts as a result of the 

complex reactions that occur in their respective NOx 

reduction pathways. The original equipment 

manufacturers (OEMs) and suppliers were eager to 

avoid any unpleasant surprises from the widespread 

adoption of these technologies. For instance, urea 

can decompose with heat and recombine to form a 

series of chemical compounds and complexes that 

may or may not be a cause for concern. NOx 

adsorber systems may form alkyl nitrates and nitrites, 

some of which have known toxicity. Because of the 

55 
Fuels Technologies

periodic fuel-rich operation during regeneration, 

NOx adsorbers may emit unburned hydrocarbons 

(HCs) since the oxidation catalysts are inoperable 

under fuel-rich conditions. Furthermore, lubricant 

additives designed to replace sulfur compounds may 

also cause unwanted emissions or may poison the 

catalytic emission control systems. 

An analytical methods development project was 

selected as the first activity since reliable methods for 

analyzing exhaust samples for the unusual 

compounds had not been developed yet. This project 

was awarded to a team from Oak Ridge National 

Laboratory (ORNL) which had extensive experience 

in this type of work for a variety of environmental 

and forensic samples. The second activity for the 

Toxics and Unregulated Emissions team is the 

analysis of samples from the APBF-DEC Lubricants 

project. The third activity is the analysis of samples 

from the urea-SCR project and the three NOx 

adsorber projects. 

Approach 

The technical team was led by ORNL with an 

industry co-chair. Members included representatives 

from engine and vehicle manufacturers, suppliers, 

and energy companies. The technical team met 

several times during FY 2005 to discuss analysis 

results from the ongoing analyses of the APBF-DEC 

samples. Polyaromatic HCs (PAHs) and nitro-PAHs 

were collected on large filters and polyurethane foam 

substrates and analyzed by Southwest Research 

Institute. Metals and other elemental analyses were 

conducted by Desert Research Institute on filter 

samples. Data flowed through the Statistics and Data 

Analysis Team led by Battelle. The team co-chairs 

participated in final project meetings for the lightduty and medium-duty NOx adsorber projects as well 

as the heavy-duty urea-SCR project. The heavy-duty 

NOx adsorber project finished during FY 2004. 

Examples of the results are presented below. 

Methods were developed in FY 2004 for 

detecting and measuring the possible urea 

decomposition products as shown in Figure 1 [1]. 

These compounds were not detected in any of the 

heavy-duty SCR exhaust samples. The high exhaust 

temperatures and “clean-up” oxidation catalyst after 

the SCR unit were expected to destroy any remaining 

 FY 2005 Progress Report 

Figure 1. Urea Decomposition Products 

urea or urea decomposition products. Additional 

information on these compounds, including 

examples of their presence in light-duty diesel 

exhaust, can be found in reference 2. 

Methods were also developed for detecting and 

measuring nitroxy-alkanes. These compounds 

include organic nitrates (R-NO3), organic nitrites 

(R-NO2) and nitro-alkanes (NO2-R). All of these 

compounds have the potential to form in the NOx 

adsorber environment, where there are active NO2 

species and organics in contact. Each NAC team 

collected dilute exhaust samples on solid-phase 

extraction cartridges prepared by the ORNL team, 

refrigerated the samples and sent them back to 

ORNL for analysis. An analysis method based on 

gas chromatography with a nitrogen-specific 

chemiluminescence detector (N-CLD) was used to 

analyze the samples. Results for the light- and 

medium-duty NOx adsorber catalysts showed the 

presence of nitroxy alkanes, but the levels were not 

consistent between triplicate cycles, probably due to 

the low levels (<1 μg/mile). The salient feature of 

this effort is that nitroxy-alkanes do not appear to be 

a significant sink for NOx in NOx adsorber systems. 

Results 

Example results of the unregulated organic 

emissions analysis show extensive destruction by 

the catalyst systems of typical engine-out emissions. 

56 
Fuels Technologies FY 2005 Progress Report 

Figure 2. Effective Destruction of 4-ring PAHs by the 

Light-Duty NOx Adsorber and Diesel 

Particulate Filter Not Affected by Aging 

(light-duty NOx adsorber project) 

Figure 3. Gas-Phase PAHs Show Increasing Emissions 

with Aging (light-duty NOx adsorber project) 

Figure 2 shows results for the four-ring PAH removal 

by the light-duty NOx adsorber system. The 

implications of this are that the diesel particulate 

filter appears to do a good job of removing the 

heavier PAHs from the engine-out exhaust, even 

under rich regeneration conditions and extensive 

aging. Conversely, Figure 3 shows that naphthalene 

and methyl naphthalene increase with the NOx 

adsorber system and aging. Because these are 

gas-phase compounds, they are less likely to be 

retained by the diesel particulate filter. 

Figure 4. 5 and 6-ring PAHs Treated Effectively by Both 

Systems A and B (heavy-duty SCR project) 

Figure 5. Heavy-Duty SCR System Shows Good 

Destruction of MSATs even after 6000 Hrs 

of Aging (heavy-duty transient test results) 

Figure 4 shows how both heavy-duty SCR 

systems treat the highest molecular weight PAHs 

effectively. The long-term aging appears to have 

little effect on the ability of the diesel particulate 

filter to treat these particulate-phase compounds. 

Furthermore, Figure 5 shows that even the lightest 

HC compounds examined, the mobile source air 

toxics (MSATs), benzene, 1,3 butadiene, 

formaldehyde and acetaldehyde, show high levels of 

destruction with these systems and little aging effect. 

57 
Fuels Technologies FY 2005 Progress Report 

Conclusions References 

The FY 2005 APBF Toxics and Unregulated 1. Ball, James C., “A Toxicological Evaluation of 

Emissions team accomplished the objectives for the Potential Thermal Degradation Products of Urea”, 

year, including the conclusion of the analyses for the Technical Report Number SRR-1999-0134. 

samples from the projects. The remaining analysis of 2. Storey, J. M. E., Sluder, C.S., Lewis, S.A., and Lewis, 

L.A., “Urea Decomposition and Storage under Light- the data from the projects will be wrapped up in FY Duty Operating Conditions,” presented at the 8th 

2006 and final reports finished. Annual CLEERS Workshop, Dearborn, MI. May 

2005. Can be found at http://www.cleers.org/ FY 2005 Publications/Presentations workshop8/presentations/storey.pdf. 

1. Storey, J.M. and S.A. Lewis. “Unregulated Emission 

Measurements from the APBF-DEC SUV Project,” 

Advanced Petroleum Based Fuel meeting at 

Southwest Research Institute, San Antonio, TX. 

March 2005. 

2. Storey, J.M. and S.A. Lewis. “Unregulated Emission 

Measurements from the APBF-DEC Heavy-Duty 

SCR Project,” Advanced Petroleum Based Fuel 

meeting at Southwest Research Institute, San 

Antonio, TX. July 2005. 

58 
Fuels Technologies FY 2005 Progress Report 

II.9 Testing at the ReFUEL Laboratory 

R. Robert Hayes 

National Renewable Energy Laboratory (NREL)

1617 Cole Blvd.

Golden, CO 80401

DOE Team Lead: Stephen Goguen 

DOE Technology Development Manager: Kevin Stork 

The ReFUEL Laboratory was further established this year as one of the premier laboratories for testing and research on 

heavy-duty engines and vehicles. Advanced facility capabilities, enhanced expertise, and new protocols were developed 

and utilized to lead and support fuels and heavy-duty hybrid vehicle research projects in support of DOE objectives and 

goals. Several test projects provided first-ever available data for new technologies and alternative fuels. Project-specific 

highlights for several of the major test projects performed at ReFUEL during fiscal year 2005 are summarized below. 

Accomplishments 

B20 Experimental Study Completed 

ReFUEL completed engine dynamometer testing 

of a modern 300 hp engine, equipped with exhaust 

gas recirculation (EGR), variable geometry 

turbocharger, and high-pressure common rail fuel 

injection with different B20 blends (20% biodiesel, 

80% conventional diesel fuel). The study provided 

an evaluation of the emissions of a modern 

production engine with various B20 blends with 

biodiesel made from feedstocks including soy oil, 

yellow grease, canola oil, and beef tallow. (Project 

Partners: Cummins, Inc.) 

ReFUEL Completes Fischer-Tropsch Fuel Blend 

Project 

ReFUEL completed a study on the effects of 

Fischer-Tropsch (FT) diesel fuel blended with 

conventional refinery diesel fuels on emissions over 

the Environmental Protection Agency (EPA) 

transient certification test with a modern 300 hp 

(2004 emissions certified) production engine. The 

study quantified the emission reductions of blending 

FT at levels of 10%, 20% and 30% in typical refinery 

fuels, compared to a specialty Tier 2 ultra-low sulfur 

diesel (ULSD) refinery fuel that is formulated for 

low emissions. Results show a reduction in 

particulate matter for the FT blends, although they 

did not reduce emissions to the specialty Tier 2 

ULSD level, at blend levels up to 30%. There was 

no significant effect of the FT blends on nitrogen 

oxide emissions. (Project Partners: Syntroleum, 

Valero) 

ReFUEL Studies Biodiesel Effects on Diesel 

Particulate Aftertreatment System Performance 

as Part of a Cooperative Research and 

Development Agreement with Cummins Inc. 

ReFUEL evaluated the effect of biodiesel on a 

2004 compliant engine retrofitted with a catalyzed 

diesel particulate filter (DPF). The study compared 

emissions with and without the DPF system installed 

on reference ULSD fuel and B20 over the EPA 

transient certification test cycle as well as evaluating 

DPF regeneration performance with biodiesel 

compared to ULSD fuel. Transient test results 

showed that measured particulate matter (PM) 

emissions were approximately 67% lower with B20 

fuel vs. ULSD fuel with the DPF aftertreatment 

system installed, as compared to a 25% measured 

PM reduction with B20 when no DPF aftertreatment 

system is present (Figure 1). Steady-state DPF 

regeneration testing showed significant measurable 

benefits from biodiesel vs. ULSD fuel, resulting in 

lower DPF balance point temperatures with biodiesel 

and significantly higher DPF regeneration rates at the 

same operating conditions for B20 vs. ULSD (Figure 

2). (Project Partners: Cummins, Johnson Matthey) 

59 
Fuels Technologies FY 2005 Progress Report 

Figure 1. Heavy-Duty Transient Test – PM Emissions, 

B20 vs. ULSD Fuel, with and without a 

Catalytic Continuously Regenerating Trap 

(CCRT) Particulate Aftertreatment System 

Figure 2. DPF Back Pressure – Regeneration Slope Test 

(1700 rpm, 250 ft-lb) Comparing B20 vs. 

Baseline 2007 Certification Diesel Fuel 

ReFUEL Completes Transit Bus Biodiesel Testing 

As part of a project to quantify the real-world 

operating costs and emissions impact of 20% 

biodiesel blend (B20), ReFUEL tested two MY 2000 

in-use buses on B20 and conventional diesel fuel as a 

reference fuel. Use of the B20 fuel resulted in 

statistically significant reductions for all regulated 

emissions. Average total hydrocarbons (THC), 

carbon monoxide (CO) and particulate matter (PM) 

emissions with B20 were lower than with the 

conventional diesel by 29%, 24%, and 18%, 

respectively (Figure 3). Average measured emissions 

of nitrogen oxides (NOx) were reduced by 4%, 

Figure 3. Transit Bus Test Results – B20 vs. 

Conventional Diesel Fuel 

which is in contrast to many engine stand studies 

which have shown the NOx emissions to generally 

increase with biodiesel use. Fuel economy on a mpg 

basis was measured to be approximately 2 -3% lower 

for the biodiesel blend (B20) due to the lower energy 

density of the fuel. Testing also supports fleet study 

work being performed by NREL on the in-use 

performance and maintenance impacts of B20 use in 

the Boulder, Colorado transit bus fleet. (Project 

Partners: Regional Transportation District) 

Chassis Testing of Bus with PM Retrofit 

Aftertreatment System and Biodiesel Blends 

ReFUEL completed a series of chassis 

dynamometer tests to evaluate the emissions benefits 

of a retrofit particulate matter (PM) aftertreatment 

system and B20 on buses which operate at the 

Cheyenne Mountain Air Force Base. This project 

provided the first known chassis dynamometer data 

on biodiesel blends and PM aftertreatment on an 

in-use bus. The study provided data to support 

decisions for implementation of the aftertreatment 

system and use of B20 at the base. (Project Partners: 

Center for Environmental Research & Technology, 

University of California Riverside, Naval Facilities 

Engineering Service Center, Tetra Tech) 

Baseline Testing Completed for Eaton/ 

International Truck and Oshkosh Refuse Hauler 

to Support Advanced Heavy Hybrid Development 

ReFUEL completed a thorough study of the fuel 

economy, emissions, and performance of a mediumduty truck and a commercial refuse hauler as the 

60 
Fuels Technologies

foundation for an evaluation of the benefits of 

hybridization. The vehicles tested will be used as a 

baseline reference for comparison with prototype 

hybrid vehicles as part of the Advanced Heavy 

Hybrid Program. This activity will allow an accurate 

assessment of the benefits of hybridization and 

model validation to accelerate development of hybrid 

technology in heavy-duty vehicles. The mediumduty truck was tested on standard drive cycles while 

the OshKosh refuse hauler was tested over 5 custom 

refuse hauler drive cycles developed for the vehicle 

based upon operational field data. (Project Partners: 

OshKosh, McNeilus, Ohio State University, Eaton, 

International Truck and Engine) 

ReFUEL Evaluates Hybrid Transit Bus 

ReFUEL evaluated the performance, emissions, 

and fuel economy of a production 60 ft. hybrid bus 

developed by GM-Allison, as well as a conventional 

baseline vehicle, over 4 different test cycles. This 

test project enabled the first known direct 

comparison of the effects of hybridization on 

measured fuel economy and emissions, with both 

vehicles utilizing identical make and model engines. 

The work included several advanced elements, 

notably the use of a custom test cycle derived from 

in-use data gathered from the King County bus fleet 

in Washington, which also incorporates grade. Work 

also included evaluating the effects of the air 

conditioning auxiliary loads. By examining effects 

of both grade and auxiliary loads, the research breaks 

new ground in heavy-duty chassis testing. The 

production hybrid bus tested will also serve as a 

baseline for comparison of planned future testing of 

an advanced prototype hybrid bus. (Project Partners: 

GM – Allison) 

Future Directions 

Several of the projects completed in FY 2005 

have led to future work that is planned at the 

ReFUEL laboratory. Specific planned efforts are as 

follows: 

• Continued study of biodiesel effects on DPF 

aftertreatment system performance is planned to 

include various biodiesel blend levels, including 

B5, and detailed particulate sampling and 

characterization studies to understand the 

differences in properties between biodiesel and 

biodiesel blend PM vs. PM from ULSD fuel. 

 FY 2005 Progress Report 

• Testing of 4 – 6 heavy-duty vehicles on the 

chassis dynamometer with B20 vs. reference fuel 

will be done to add to the scant collection of 

existing published data regarding B20 effects on 

the performance and emissions of heavy-duty 

vehicles over chassis dynamometer test drive 

cycles that simulate real-world duty cycles. This 

work is to be performed as part of a cooperative 

research and development agreement with the 

National Biodiesel Board. 

• ReFUEL has plans to expand its transient 

altitude simulation testing capabilities to enable 

transient testing of engines and vehicles at sea 

level conditions as well as Denver altitude. 

Current capabilities only allow for lower-altitude 

simulation during steady-state testing. 

• The ReFUEL laboratory participates as part of 

the EPA/Engine Manufacturers Association 

Calibration Standards Task Force, which 

provides leadership and input for test methods 

and protocol specifications related to EPA 

regulations for vehicles and engines as published 

in the Code of Federal Regulations. As part of 

this group, ReFUEL has been selected to 

participate in a round-robin lab correlation study 

of a 2007 compliant engine to quantify and 

confirm lab-to-lab agreement and test methods 

between the nation’s leading heavy-duty engine 

emissions laboratories on future-technology 

engines with drastically reduced emissions. 

• The ReFUEL laboratory will also continue to 

conduct heavy-duty hybrid vehicle tests in FY 

2006 in support of the projects discussed above 

and is participating in an EPA-led heavy-duty 

vehicle test procedure development effort to 

enable quantification of fuel savings and 

emission benefits of heavy-duty hybrid vehicles 

to support tax credit requirements and state 

implementation plans for air quality 

improvement. 

FY 2005 Publications/Presentations 

Peer-reviewed Publications 

1. “Regulated Emissions from Biodiesel Tested in 

Heavy-Duty Engines Meeting 2004 Emission 

Standards,” 2005 SAE Fuels and Lubricants Meeting, 

Paper No. 2005-01-2200, Robert L. McCormick, 

Christopher J. Tennant, R. Robert Hayes, 

61 
Fuels Technologies FY 2005 Progress Report 

Stuart Black, John Ireland, Tom McDaniel, 

Aaron Williams, Mike Frailey (NREL); 

Christopher A. Sharp (Southwest Research Institute)

2. “Achievement of Low Emissions by Engine 

Modification to Utilize Gas-to-Liquid Fuel and 

Advanced Emission Controls on a Class 8 Truck,” 

2005 SAE Powertrain and Fluids Systems 

Conference, Paper No. 2005-01-3766, Teresa L. 

Alleman, Christopher J. Tennant, R. Robert Hayes 

(NREL); Matt Miyasato, Adewale Oshinuga 

(SCAQMD); Greg Barton (ATL); Marc Rumminger 

(Cleaire Advanced Emission Controls); Vinod 

Duggal, Christopher Nelson (Cummins Inc.); 

Mike May (Ricardo Inc.); Ralph A. Cherrillo (Shell 

Global Solutions (US) Inc.)

 Presentations 

1. “Emissions Testing of a RTD Bus”, Bob Hayes, 

presented to 2005 Biodiesel Technical Workshop, 

November 9-10, Denver, CO 

2. “Biodiesel and DPF Operation in an EGR Engine”, 

Bob Hayes, presented to 2005 Biodiesel Technical 

Workshop, November 9-10, Denver, CO 

3. “Testing of Biodiesel Fuels and Blends in a Modern 

Production Medium-Duty Engine”, presented to Fuels 

Technologies Merit Review, Denver, CO, March 

2005 

62 
Fuels Technologies FY 2005 Progress Report 

III Fuel Property Effects on Advanced 

Combustion Regimes

63 
Fuels Technologies FY 2005 Progress Report 

64
Fuels Technologies FY 2005 Progress Report 

III.1 Using Non-Traditional Diesel Fuels and Optical Diagnostics to Understand 

and Optimize In-Cylinder Processes 

Charles J. Mueller (Primary Contact), Ansis Upatnieks1, Glen C. Martin 

Sandia National Laboratories 

7011 East Ave., MS 9053 

Livermore, CA 94550-9517 

DOE Technology Development Manager: Kevin Stork 

Objectives 

• Determine whether fuel changes can enable an efficient, 2010-emissions-compliant combustion strategy 

that is not limited by difficulties with controlling ignition timing (at all loads) and with excessive pressurerise rates (at high loads). Avoiding such difficulties has been challenging with homogeneous charge 

compression ignition (HCCI), the prevailing strategy to date. 

• Introduce a parameter that accurately quantifies the proximity of a reactant mixture to its stoichiometric 

condition when fuel molecules contain oxidizer elements or when oxidizer molecules contain fuel 

elements. Such a parameter is important for understanding mixture stoichiometry effects on lowtemperature combustion processes by quantifying mixture stoichiometry once reactions have begun; it is 

also important when oxygenated fuels are used. 

Approach 

• Upgrade experimental facility to enable the simulation of high exhaust gas recirculation (EGR) rates. 

Select a highly oxygenated fuel with a short ignition delay for testing. Conduct engine experiments with 

oxygenated fuel at high EGR rates to determine whether high-efficiency, emissions-compliant operation is 

achievable when employing a mixing-controlled combustion strategy. 

• Develop a clear understanding of why conventional parameters for the quantification of mixture 

stoichiometry can be inaccurate when fuel molecules contain oxidizer elements or when oxidizer 

molecules contain fuel elements. Derive a parameter that properly quantifies mixture stoichiometry under 

these conditions. Show the relationship between the new parameter and existing parameters such as the 

equivalence ratio. Quantify the errors involved when the equivalence ratio is used outside of its range of 

validity. 

Accomplishments 

• Both objectives were achieved. 

• Fuel changes were used to enable a high-efficiency (>44% indicated efficiency), 2010-emissionscompliant (<0.2 g/hp-hr NOx, <0.05 filter smoke number) combustion strategy where ignition timing is 

simply controlled by injection timing, and peak pressure-rise rates are lower than for conventional diesel 

combustion. Insight into the important in-cylinder processes was gained through the application of optical 

diagnostics. This accomplishment directly supports DOE objectives of identifying and enhancing the 

understanding of high-efficiency, clean combustion modes. The strategy could be an attractive alternative 

to HCCI, or it could be used at low- and high-load conditions with HCCI at moderate loads. 

• A parameter was derived that accurately quantifies mixture stoichiometry after reactions have begun or 

when oxygenated fuels are used. This accomplishment directly supports the DOE objective of developing 

1Currently employed at General Motors Research and Development Center in Warren, Michigan. 

65 
Fuels Technologies FY 2005 Progress Report 

the fundamental science base required to understand and optimize high-efficiency, clean combustion 

modes. 

Future Directions 

• Determine the extent to which the high-efficiency, clean combustion alternative to HCCI identified in FY 

2005 research activities can be achieved with more-traditional fuels such as #2 diesel, biodiesel, and 

Fischer-Tropsch paraffins. 

• Continue investigations into the reasons for higher NOx emissions when biodiesel is used in conventional 

diesel combustion systems. 

• Demonstrate the first successful application of two-photon laser-induced fluorescence detection of NO 

within an operating engine. 

Introduction 

Emissions regulations coming into force in 2010 

for heavy-duty on-highway engines, combined with 

increasing concerns over the stability of imported 

petroleum supplies, are driving the development of 

cleaner, more efficient engine technologies. One 

promising approach to meeting these challenges 

without costly exhaust aftertreatment systems is 

low-temperature combustion (LTC). In LTC, 

in-cylinder temperatures are low enough that high 

nitrogen oxide (NOx) emissions are avoided, and 

high particulate matter (PM) emissions are avoided 

by premixing the fuel/oxidizer mixture to overall 

lean conditions and/or decreasing in-cylinder 

temperatures below those required for soot 

formation. The fundamentals of LTC are not yet 

well understood, however, and this has been a barrier 

to it being successfully employed in production 

engines. For example, implementation of HCCI 

(the prevailing LTC strategy to date) has been slow 

due to challenges with controlling ignition timing 

and limiting peak pressure-rise rates at high loads. 

It is known that fuel properties, fuel/oxidizer mixture 

preparation, and exhaust gas recirculation (EGR) 

level are important, but it is not yet known how to 

use these parameters to optimally employ LTC in 

engine applications. 

Work in our laboratory has been focused on 

providing experimental and theoretical results to 

support the development of a fundamental science 

base of fuel and mixture-preparation effects on LTC 

to 1) employ LTC operating strategies with improved 

performance characteristics, 2) determine the extent 

to which fuel changes can facilitate operation in LTC 

regimes, and 3) provide theoretical tools necessary 

to better understand the effects of mixture 

stoichiometry on LTC processes. 

Approach 

The approach to developing the science base of 

fuel and mixture-preparation effects on LTC includes 

both experimental and theoretical components. The 

experimental work has been focused on using 

advanced diagnostics in the Sandia Compressionignition Optical Research Engine (SCORE) to 

investigate the relationships between fuel 

characteristics, in-cylinder processes, and engine-out 

emissions. The theoretical work has concentrated on 

understanding mixture stoichiometry under nontrivial conditions, such as once reactions have begun 

or when oxygenated fuels are used, so that this 

important LTC control parameter can be properly 

quantified and its effects understood. 

The SCORE is a single-cylinder version of a 

modern-technology, Caterpillar® 4-stroke direct 

injection (DI) diesel engine that has been modified 

by Sandia to provide extensive optical access into the 

combustion chamber [1]. The SCORE is based on 

the Caterpillar 3176/C-10 engine family. 

A schematic of the SCORE is shown in Figure 1. 

A large window in the piston bowl enables lasersheet access and imaging of combustion processes 

within the engine during operation, as do additional 

windows in the upper periphery of the cylinder liner 

and the piston bowl rim. Specifications of the 

SCORE are provided in Table 1. The ability to use a 

wide range of advanced optical diagnostics, coupled 

with exhaust-gas analysis equipment to measure 

66 
Fuels Technologies FY 2005 Progress Report 

Figure 1. Schematic of Sandia Compression-Ignition 

Optical Research Engine (SCORE) 

NOx, smoke, HC, CO, CO2, and O2, makes the 

SCORE a versatile instrument for studying the 

details of fuel effects on in-cylinder processes and 

corresponding impacts on emissions. Optical-engine 

data also complement measurements from multicylinder production engines tested over standard 

driving cycles, and can be used to verify the accuracy 

of computational fluid dynamics models. 

Results 

Experimental study of new LTC strategy – As 

described above, a primary objective of FY 2005 

activities was to study mixing-controlled reaction 

under high-EGR conditions as a means to achieve 

high-efficiency, clean combustion while avoiding the 

control problems and excessive pressure-rise rates 

that can occur with HCCI. We have called this 

strategy dilute clean diesel combustion (DCDC). 

DCDC can be viewed as traditional diesel 

combustion that has been shifted into the LTC regime 

by the use of high EGR levels, and in this way it is 

similar to “smokeless rich combustion” [2,3], but 

Table 1. SCORE Specifications 

Research engine type 1-cyl. vers. of Cat 3176/C-10 

Cycle 4-stroke CIDI 

Valves per cylinder 4 

Bore 125 mm 

Stroke 140 mm 

Intake valve opena 32° BTDC exhaust 

Intake valve closea 153° BTDC compression 

Exhaust valve opena 116° ATDC compression 

Exhaust valve closea 11° ATDC exhaust 

Connecting rod length 225 mm 

Connecting rod offset None 

Piston bowl diameter 90 mm 

Piston bowl depth 16.4 mm 

Squish height 1.5 mm 

Swirl ratiob 0.59 

Displacement per cyl. 1.72 liters 

Geometric compr. ratio 11.27:1 

Simulated compr. ratioc 16.00:1 

a All valve timings are for lift @ 0.03 mm 

b Measured at the Caterpillar Tech. Center using an AVL swirl 

meter 

c TDC temperature, pressure, and density in the production engine 

are matched in the optical engine by preheating and boosting the 

pressure of the intake air 

DCDC also uses a “clean” fuel to suppress PM 

emissions. The control problems of HCCI are 

avoided because with DCDC, as with traditional 

diesel operation, combustion phasing is controlled by 

fuel-injection timing. Figure 2 shows results from 

DCDC experiments that were run at steady-state 

conditions using neat diethylene glycol diethyl ether 

(DGE), a short-ignition-delay, oxygenated fuel. 

Emissions are plotted as a function of the mole 

fraction of oxygen in the intake charge. NOx 

emissions are below the 2010 limit for intake oxygen 

mole fractions less than approximately 14%, and 

smoke emissions are well below 0.05 filter smoke 

number (FSN) over the range of oxygen 

concentrations in the study. High fuel-conversion 

efficiency (defined as the product of thermal 

67 
Fuels Technologies

Figure 2. Engine-out NOx and smoke emissions, 

indicated fuel-conversion efficiency, and 

apparent heat-release rate data (inset) for 

DCDC operation. Data obtained at 1200 rpm 

and an engine load of 7.0 bar indicated mean 

effective pressure, for intake temperature and 

pressure of 25°C and 2.23 bar (abs.), 

respectively. EGR was simulated with 

nitrogen gas. 

efficiency and combustion efficiency [4]) is 

maintained at intake oxygen concentrations as low as 

approximately 11%, indicating that there is a 

substantial window for desirable DCDC operation. 

The inset shows that heat-release rates are even lower 

under DCDC conditions than for traditional diesel 

combustion, which should lead to quieter engine 

operation. Longer flame lift-off lengths and more 

diffuse combustion are observed as dilution level 

increases (see Figure 3). The total natural luminosity 

signal intensity drops by two orders of magnitude as 

the intake oxygen concentration is lowered from 21% 

to 9%, indicating significant decreases in soot 

volume fraction and/or temperature under DCDC 

operation. Results have been acquired at up to 18 bar 

indicated mean effective pressure, which represents 

 FY 2005 Progress Report 

3/4-load operation. See Refs. [5,6] for further details 

about DCDC operation. 

Theoretical study of quantification of mixture 

stoichiometry – A parameter called the oxygen 

equivalence ratio, denoted φΩ, was derived to 

accurately quantify mixture stoichiometry in 

situations where fuel molecules contain oxidizer 

elements or oxidizer molecules contain fuel 

elements. The oxygen equivalence ratio is defined as 

the amount of oxygen (moles or mass) required to 

convert all fuel elements to saturated stoichiometric 

products (SSPs), divided by the amount of oxygen 

present in the given mixture. The oxygen 

equivalence ratio can be expressed mathematically 

as: 

where nC, nH, and nO are the numbers of carbon, 

hydrogen, and oxygen atoms, respectively. An SSP 

is defined as a product species with no net charge, 

each of whose constituent atoms has a saturated (i.e., 

filled or closed-shell) valence orbital. Atoms that are 

initially bound in SSPs in the reactants are neglected 

in the calculation of the oxygen equivalence ratio. 

The oxygen equivalence ratio is a valid measure of 

mixture stoichiometry in any mixture for which the 

SSPs are CO2, H2O, N2, and/or noble gases. See 

Ref. [7] for details about the oxygen equivalence 

ratio. 

Conclusions 

• Fuel changes were found to enable a highefficiency (>44% indicated fuel-conversion 

efficiency), 2010-emissions-compliant 

(<0.2 g/hp-hr NOx, <0.05 filter smoke number) 

combustion strategy where ignition timing is 

simply controlled by injection timing, and peak 

pressure-rise rates are lower than for 

conventional diesel combustion. Insight into the 

important in-cylinder processes was gained 

through the application of optical diagnostics. 

This accomplishment directly supports DOE 

objectives of identifying and enhancing the 

understanding of fuel effects on high-efficiency, 

clean combustion modes. 

68 
Fuels Technologies FY 2005 Progress Report 

Figure 3. Natural luminosity images for combustion at (left) 21% oxygen (i.e., undiluted) and (right) 9% oxygen at same 

speed, load, and intake conditions as Figure 2. Numbers in upper- and lower-right corners of each image 

indicate crank angle at which image was acquired and camera gain, respectively. Higher camera gain = fainter 

luminosity signal. Images of undiluted combustion (left) show high signal levels due to soot incandescence; 

images for dilute case (right) show more diffuse combustion and are typically 1000 times dimmer, indicating 

that hot soot is no longer present. 

• A parameter was derived that accurately 

quantifies mixture stoichiometry after reactions 

have begun or when oxygenated fuels are used. 

This accomplishment directly supports the DOE 

objective of developing the fundamental science 

base of fuel and mixture-preparation effects 

required to understand and optimize highefficiency, clean combustion modes. 

Special Recognitions & Awards 

1. Society of Automotive Engineers Arch T. Colwell 

Merit Award, for paper entitled “Effects of 

Oxygenates on Soot Processes in DI Diesel Engines: 

Experiments and Numerical Simulations,” SAE 

Technical Paper 2003-01-1791. This was one of 11 

papers honored in 2004 for being most innovative and 

original out of approximately 2,500 papers published 

during the preceding year. 

2. Society of Automotive Engineers Lloyd L. Withrow 

Distinguished Speaker Award. This was one of 8 

such awards presented in 2005 to recognize 

individuals who have received SAE’s Oral 

Presentation Award more than twice. 

FY 2005 Publications 

1. Upatnieks, A. and Mueller, C.J., “Clean, Controlled 

DI Diesel Combustion Using Dilute, Cool Charge Gas 

and a Short-Ignition-Delay, Oxygenated Fuel,” SAE 

Paper 2005-01-0363. 

2. Upatnieks, A., Mueller, C.J., and Martin, G.C., 

“The Influence of Charge-Gas Dilution and 

Temperature on DI Diesel Combustion Processes 

Using a Short-Ignition-Delay, Oxygenated Fuel,” 

SAE Paper 2005-01-2088. 

3. Mueller, C.J., “The Quantification of Mixture 

Stoichiometry When Fuel Molecules Contain 

69 
Fuels Technologies FY 2005 Progress Report 

Oxidizer Elements or Oxidizer Molecules Contain 

Fuel Elements,” SAE Paper 2005-01-3705. 

4. Mueller, C.J., Martin, G.C., Briggs, T.E., and 

Duffy, K.P., “An Experimental Investigation of InCylinder Processes under Dual-Injection Conditions 

in a DI Diesel Engine,” SAE Transactions, Vol. 113, 

Sect. 3, 2004. 

5. Buchholz, B.A., Mueller, C.J., Upatnieks, A., 

Martin, G.C., Pitz, W.J., and Westbrook, C.K., 

“Using Carbon-14 Isotope Tracing to Investigate 

Molecular Structure Effects of the Oxygenate Dibutyl 

Maleate on Soot Emissions from a DI Diesel Engine,” 

SAE Transactions, Vol. 113, Sect. 4, 2004. 

6. Buchholz, B.A., Mueller, C.J., Martin, G.C., 

Cheng, A.S., Dibble, R.W., and Frantz, B.R., 

“Tracing Fuel Component Carbon in the Emissions 

from Diesel Engines,” Nuc. Inst. and Meth. Phys. B, 

Vol. 223-224, pp. 837-841, 2004. 

7. Mueller, C.J., “In-Cylinder Processes under Early 

Direct-Injection Diesel HCCI Conditions,” Proc. 

of DOE Advanced Engine Combustion, Emission 

Control, and Fuels Program Review, Argonne 

National Laboratory, Argonne, IL, 2004. 

8. Martin, G.C., Mueller, C.J., and Lee, C.F., “TwoPhoton Laser-Induced Fluorescence of Nitric Oxide in 

a Diesel Engine,” submitted for presentation at SAE 

World Congress, 2006. 

9. Martin, G.C., Mueller, C.J., and Lee, C.F., “TwoPhoton NO LIF Measurements in a Diesel Engine,” 

submitted to Applied Optics, 2005. 

10. Cheng, A.S., Upatnieks, A., and Mueller, C.J., 

“Investigation of the Impact of Biodiesel Fueling on 

NOx Emissions Using an Optical DI Diesel Engine,” 

submitted to International Journal of Engine 

Research, 2005. 

FY 2005 Presentations 

1. Mueller, C.J., “Dilute Clean Diesel Combustion 

Achieves Low Emissions and High Efficiency While 

Avoiding Control Problems of HCCI,” Caterpillar 

10/4 Tech Team Meeting, Mossville, IL (September 

27, 2005). 

2. Mueller, C.J., “Dilute Clean Diesel Combustion 

Achieves Low Emissions and High Efficiency While 

Avoiding Control Problems of HCCI,” Advanced 

Engine Combustion Working Group Meeting, Detroit, 

MI (September 13, 2005). 

3. Mueller, C.J., “Dilute Clean Diesel Combustion 

Achieves Low Emissions and High Efficiency While 

Avoiding Control Problems of HCCI,” 11th Annual 

Diesel Engine Emissions Reduction (DEER) 

Conference, Chicago, IL (August 22, 2005). 

4. Mueller, C.J., “Emerging Trends in Engine 

Combustion,” invited plenary address at Oil-Sands 

Chemistry and Engine Emissions Workshop, 

Edmonton, Canada (June 6, 2005). 

5. Mueller, C.J., “Optical-Engine Studies of Fuel Effects 

on Low-Temperature Combustion Processes: Sandia 

Diagnostics and Activities,” Caterpillar/ExxonMobil/ 

Sandia HECC Project Teleconference (May 19, 

2005). 

6. Upatnieks, A., “The Influence of Charge-Gas Dilution 

and Temperature on DI Diesel Combustion Processes 

Using a Short-Ignition-Delay, Oxygenated Fuel,” SAE 

Spring 2005 Fuels and Lubricants Meeting, Rio de 

Janeiro, Brazil (May 11, 2005). 

7. Mueller, C.J., “Engine Combustion Research at the 

CRF,” Sandia Energy PDS Meeting, Livermore, CA 

(May 4, 2005). 

8. Upatnieks, A., “Clean, Controlled DI Diesel 

Combustion Using Dilute, Cool Charge Gas and a 

Short-Ignition-Delay, Oxygenated Fuel,” SAE 2006 

World Congress, Detroit, MI (April 11, 2005). 

9. Mueller, C.J., “Optical-Engine Studies of Fuel Effects 

on Low-Temperature and CIDI Combustion 

Processes,” DOE Fuels Technology R&D Program 

Review, Golden, CO (March 8, 2005). 

10. Mueller, C.J., “The Quantification of Mixture 

Stoichiometry When Fuel Molecules Contain 

Oxidizer Elements or Oxidizer Molecules Contain 

Fuel Elements,” HCCI University Working Group 

Meeting, Livermore, CA (February 3, 2005). 

11. Mueller, C.J., “An Investigation into Causes of 

Increased NOx Emissions with Biodiesel Fueling,” 

Advanced Engine Combustion Working Group 

Meeting, Livermore, CA (February 1, 2005). 

12. Upatnieks, A., “Dilute Clean Diesel Combustion 

Using a Short-Ignition-Delay, Oxygenated Fuel,” 

Advanced Engine Combustion Working Group 

Meeting, Livermore, CA (February 1, 2005). 

References 

1. Mueller, C.J., Martin, G.C., Briggs, T.E., and 

Duffy, K.P., “An Experimental Investigation of InCylinder Processes under Dual-Injection Conditions 

in a DI Diesel Engine,” SAE Paper 2004-01-1843, 

SAE Trans., Vol. 113, Sect. 3, 2004. 

2. Akihama, K., Takatori, Y., Inagaki, K., Sasaki, S., 

and Dean, A.M., “Mechanism of the Smokeless Rich 

Diesel Combustion by Reducing Temperature,” SAE 

Paper 2001-01-0655, SAE Trans., Vol. 110, Sect. 3, 

2001. 

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Fuels Technologies

3. Pickett, L.M. and Siebers, D.L., “Non-Sooting, Low 

Flame Temperature Mixing-Controlled DI Diesel 

Combustion,” SAE Paper 2004-01-1399, SAE Trans., 

Vol. 113, Sect. 4, 2004. 

4. Heywood, J.B., Internal Combustion Engine 

Fundamentals, McGraw-Hill, New York, 1988, p. 52. 

5. Upatnieks, A. and Mueller, C.J., “Clean, Controlled 

DI Diesel Combustion Using Dilute, Cool Charge Gas 

and a Short-Ignition-Delay, Oxygenated Fuel,” SAE 

Paper 2005-01-0363, 2005. 

 FY 2005 Progress Report 

6. Upatnieks, A., Mueller, C.J., and Martin, G.C., 

“The Influence of Charge-Gas Dilution and 

Temperature on DI Diesel Combustion Processes 

Using a Short-Ignition-Delay, Oxygenated Fuel,” 

SAE Paper 2005-01-2088, SAE Trans., Vol. 114, 

Sect. 4, 2005. 

7. Mueller, C.J., “The Quantification of Mixture 

Stoichiometry When Fuel Molecules Contain 

Oxidizer Elements or Oxidizer Molecules Contain 

Fuel Elements,” SAE Paper 2005-01-3705, SAE 

Trans., Vol. 114, Sect. 4, 2005. 

71 
Fuels Technologies FY 2005 Progress Report 

III.2 Chemical Kinetic Modeling of Combustion of Automotive Fuels 

William J. Pitz (Primary Contact), Charles K. Westbrook 

Lawrence Livermore National Laboratory 

P. O. Box 808, L-091 

Livermore, CA 94551 

DOE Team Lead: Stephen Goguen 

DOE Technology Development Manager: Kevin Stork 

Objectives 

• Develop detailed chemical kinetic reaction models for components of fuels, including oxygenated species 

and additives used in diesel, spark-ignition and homogeneous charge compression ignition (HCCI) engines 

• Develop surrogate mixtures of hydrocarbon components to represent real fuels and lead to efficient 

reduced combustion models 

• Characterize the role of fuel composition on production of emissions from practical automotive engines 

Approach 

• Identify individual fuel components and their molecular structures 

• Develop kinetic reaction mechanisms for fuel components and additives 

• Compute ignition and flame structure for fuel components under diesel, spark-ignition and HCCI 

conditions 

• Compute ignition and flame structure for surrogate mixtures of fuel components under diesel, 

spark-ignition and HCCI conditions 

Accomplishments 

• Completed models for chemical kinetics of combustion of two major fuel components, toluene and methyl 

cyclohexane, and of an oxygenated diesel fuel additive, dimethyl carbonate 

• Continued development of surrogate mixtures to describe HCCI ignition 

• Identified specific chemical species contributing to problems in providing an optimal surrogate 

• Continued past studies of mechanisms by which oxygenated diesel fuel components reduce soot 

production 

Future Directions 

• Extend model capabilities to additional classes of fuel components 

• Continue development of increasingly complex surrogate fuel mixtures 

• Increase collaborations with programs outside Lawrence Livermore National Laboratory (LLNL) dealing 

with automotive fuel issues 

Introduction grouped into a number of structurally distinct classes, 

including n-paraffins, branched paraffins, cyclic and 

Automotive hydrocarbon fuels consist of branched cyclic paraffins, olefins, oxygenates, and 

complex mixtures of hundreds or even thousands of aromatics (see Figure 1). The fractional amounts of 

different components. These components can be 

72 
Fuels Technologies FY 2005 Progress Report 

Figure 1. Examples of the major classes of hydrocarbon 

species present in practical transportation fuels. 

These specific examples are n-hexane, 

2,3-dimethyl pentane, 2-hexene, cyclo-hexane, 

toluene, and tri-propylene glycol monomethyl 

ether (TPGME). 

these components are quite different in gasoline, 

diesel fuel and jet fuels, which contributes to the very 

different combustion characteristics of each of these 

types of combustion systems. 

To support large-scale computer simulations of 

each kind of engine, it is necessary to provide 

reliable chemical kinetic models for each of these 

fuel classes. However, few specific hydrocarbon 

components of some of these fuel classes have been 

modeled. For example, although models for benzene 

and toluene have been developed, models for few if 

any larger aromatic compounds such as naphthalene 

or styrene currently exist. Similarly, detailed models 

for small n-paraffins such as propane, n-heptane and 

even n-octane have been developed, but detailed 

models do not yet exist for the much larger versions 

characteristic of diesel fuels, such as n-hexadecane. 

A current approach to this problem is to construct a 

detailed model containing one or more 

representatives of each class of components to serve 

as a surrogate mixture. In order for such a surrogate 

mixture model to be useful, each component must 

have a well-tested detailed kinetic model that can be 

included. This high-level approach can create 

realistic substitutes for gasoline or diesel fuel that 

reproduce experimental behavior of the practical real 

fuels, but these substitutes, or surrogates, will also 

then be reproducible in both experiments and 

modeling studies. Detailed kinetic models for groups 

of fuels can then be simplified as needed for 

inclusion in multidimensional computational fluid 

dynamics (CFD) models or used in full detail for 

purely kinetic modeling. 

Our recent studies continue to address sootproducing characteristics of diesel fuels. The 

kinetics of oxygenated chemical species and their 

effects on sooting remain a major goal, and we have 

added several new species to the list of available 

oxygenates, but our current focus is to understand 

and calculate the separate contributions of the major 

constituent chemical species on sooting by regular 

diesel fuels. This will lead to improved 

understanding of the effects of these diesel fuel 

components on engine performance and pollutant 

formation and to development of efficient simplified 

chemical models for diesel fuel for use in 

multidimensional CFD models of engine 

combustion. Other applications to ignition and 

pollutant formation in HCCI engines have also been 

pursued, using a multizone spatial model for this type 

of engine and using suitable surrogates for both 

diesel fuel and gasoline. 

Approach 

Chemical kinetic modeling has been developed 

uniquely at LLNL to investigate combustion of 

hydrocarbon fuels in practical combustion systems 

such as diesel and HCCI engines. The basic 

approach is to integrate chemical rate equations for 

chemical systems of interest, within boundary 

conditions related to the specific system of 

importance. This approach has been used 

extensively for diesel and HCCI engine combustion, 

providing better understanding of ignition, soot 

production, and NOx emissions from these engines 

in fundamental chemical terms. 

The underlying concept for diesel engines is that 

ignition takes place at very fuel-rich conditions, 

producing a mixture with high concentrations of 

species such as acetylene, ethene, propene and others 

which are well known to lead to soot production. 

Some changes in combustion conditions reduce the 

post-ignition levels of these soot precursors and 

reduce soot production, while other changes lead to 

increased soot emissions. The LLNL project 

computes this rich ignition using kinetic modeling, 

leading to predictions of the effect such changes 

might have on soot production and emissions. 

Kinetic reaction models were developed for the 

oxygenated additives proposed by a DOE/industry 

panel of experts. We then computed diesel ignition 

73 
Fuels Technologies

and combustion using heptane as a reasonable diesel 

fuel surrogate model, mixed with oxygenated 

additives. The impact of the additives on predicted 

levels of soot-producing chemical species could then 

be assessed. 

Ignition under HCCI engine conditions is closely 

related to that in diesel engines, since both are 

initiated by compression ignition of the fuel/air 

mixtures. In very fuel-lean HCCI ignition, the 

premixing of fuel and air in the gaseous state results 

in no soot and extremely low NOx production. 

Kinetic modeling has proven to be exceedingly 

valuable in predicting not only the time of ignition in 

HCCI engines, but also the duration of burn and the 

emissions of unburned hydrocarbons, CO, NOx and 

soot. 

Results 

Our kinetic models assume that soot production 

in diesel combustion occurs from reactions of 

chemical species created in fuel-rich ignition near the 

fuel injection location. Because there is insufficient 

oxygen in this region to burn the fuel completely, the 

hydrocarbon species remaining there react instead to 

produce soot. Our kinetics calculations show that 

when the fuel itself contains some oxygen, that 

oxygen helps convert more of the ignition products 

into chemical species that do not contribute to soot 

production. 

During the past year, the LLNL project has 

examined additional oxygenated hydrocarbon 

species that have been proposed as possible diesel 

fuels or additives, specifically dimethyl carbonate, 

which includes significant amounts of oxygen 

imbedded in the primarily hydrocarbon fuel 

molecule. A detailed chemical kinetic reaction 

mechanism has been developed for this fuel, and the 

resulting model was used to assess its sooting 

tendency. We have also been able to distinguish 

between the soot-reducing abilities of different 

oxygenated hydrocarbons, based on the location of 

the O atoms within that molecule. Some structural 

factors, including some that are typical of biodiesel 

fuel species, actually reduce the effectiveness of such 

species in reducing sooting. Our recent publication 

summarizing several years of experimental and 

kinetic modeling work describing the mechanisms by 

 FY 2005 Progress Report 

which oxygenated additives influence sooting was 

selected as a winner of the Society of Automotive 

Engineers Arch Colwell Award of Merit for 2005. 

We have completed and submitted for 

publication kinetic mechanisms for the large olefin 

di-isobutylene, which is closely related to iso-octane, 

and for methyl cyclohexane, which is a very 

important cyclic paraffin. These non-aromatic cyclic 

hydrocarbons are expected to become increasingly 

important because they are present in particularly 

large quantities in diesel fuels derived from Canadian 

oil sands, currently estimated to be the world’s 

second largest petroleum resource. We have 

identified new reaction pathways in methyl 

cyclohexane that have large impacts on its ignition 

(see Figure 2). 

Finally, we have continued computational 

studies of uses of surrogate gasoline mixtures to 

describe HCCI ignition. The multizone model has 

been shown to reproduce nearly all of the important 

features of engine performance and emissions 

characteristics when the engines are operated in the 

normal, fuel-lean regime. We are using the same 

Figure 2. Two related H atom transfer reactions in 

n-heptane and methyl cyclohexane, showing 

how the cyclic structure alters the number of 

free rotors (indicated as R above) differently in 

the two reactions. These differences produce 

different rates of what otherwise appears to be 

the same reaction, leading to different rates of 

ignition. 

74 
Fuels Technologies FY 2005 Progress Report 

approach to examine other operating regimes, such 

as operation with extensive amounts of exhaust gas 

recirculation or other forms of dilution but with 

richer fuel/air mixtures. 

Conclusions 

Kinetic modeling provides a unique tool to 

analyze combustion properties of diesel, sparkignition and HCCI engines. A kinetic model can be 

very cost-effective as an alternative to extended 

experimental analyses and as guidance for more 

efficient experimentation, and computations can also 

provide a fundamental explanation of the reasons for 

the observed results. LLNL kinetic models are 

providing this valuable capability for engine research 

at many university and industrial facilities in the 

United States and are essential tools in engine 

research. 

FY 2005 Publications/Presentations 

1. Glaude, P.-A., Pitz, W.J., and Thomson, M.J., 

“Chemical Kinetic Modeling of Dimethyl Carbonate 

in an Opposed-Flow Diffusion Flame”, Proc. 

Combust. Inst. 30, 1111-1118 (2005). 

2. Mueller, C.J., Pitz, W.J., Pickett, L.M., Martin, G.C., 

Siebers, D.L., and Westbrook, C.K., “Effects of 

Oxygenates on Soot Processes in DI Diesel Engines: 

Experiments and Numerical Simulations”, Society of 

Automotive Engineers SAE 2003-01-1791 (2003) and 

Japan Society of Automotive Engineers JSAE 

20030193 (2003). 

3. Westbrook, C.K., Mizobuchi, Y., Poinsot, T.J., 

Smith, P.J., and Warnatz, J., “Computational 

Combustion”, Proc. Combust. Inst. 30, 125-157 

(2005). 

4. Zheng, X., Lu, T.F., Law, C.K., and Westbrook, C.K., 

“Experimental and Computational Study of NonPremixed Ignition of Dimethyl Ether”, Proc. 

Combust. Inst. 30, 1101-1109 (2005). 

5. Naik, C.V., Pitz, W.J., Sjöberg, M., Dec, J.E., 

Orme, J., Curran, H.J., Simmie, J.M., and Westbrook, 

C.K., “Detailed Chemical Kinetic Modeling of 

Surrogate Fuels for Gasoline and Application to an 

HCCI Engine”, Society of Automotive Engineers 

publication SAE 2005-01-3741 (2005). 

6. Naik, C.V., Pitz, W.J., Sjöberg, M., Dec, J.E., 

Orme, J., Curran, H.J., Simmie, J.M., and Westbrook, 

C.K., “Detailed Chemical Kinetic Modeling of 

Surrogate Fuels for Gasoline and Application to an 

HCCI Engine”, Joint Meeting of the US Sections of 

The Combustion Institute, Philadelphia, PA, March 

2005. 

7. Metcalfe, W., Curran, H.J., Simmie, J.M., Pitz, W.J., 

and Westbrook, C.K., “The Development of a 

Detailed Chemical Kinetic Mechanism for 

Di-isobutylene and Comparison to Shock Tube 

Ignition Times”, Joint Meeting of the US Sections 

of The Combustion Institute, Philadelphia, PA, 

March 2005. 

8. Curran, H.J., Jayaweera, T.M., Pitz, W.J., and 

Westbrook, C.K., “A Detailed Modeling Study of 

Propane Oxidation”, Western States Section meeting 

of The Combustion Institute, 2004. 

9. Buchholz, B.A., Mueller, C.J., Upatnieks, A., 

Martin, G.C., Pitz, W.J., and Westbrook, C.K., 

“Using Carbon-14 Isotope Tracing to Investigate 

Molecular Structure Effects of the Oxygenate Dibutyl 

Maleate on Soot Emissions from a DI Diesel Engine”, 

Society of Automotive Engineers publication SAE 

2004-01-1849 (2004). 

10. Pitz, W.J., Naik, C.V., Mhaulduin, T.N., 

Westbrook, C.K., Curran, H.J., Orme, J.P., and 

Simmie, J.M., “Modeling and Experimental 

Investigation of Methylcyclohexane Ignition in 

a Rapid Compression Machine”, submitted to 

Thirty-First International Symposium on Combustion, 

2005. 

11. Silke, E.J., Curran, H.J., Simmie, J.M., Pitz, W.J., and 

Westbrook, C.K., “A Rapid Compression Machine 

Modelling Study of the Heptane Isomers”, European 

Combustion Meeting of The Combustion Institute, 

2004. 

12. Metcalfe, W.K., Pitz, W.J., Curran, H.J., 

Simmie, J.M., and Westbrook, C.K., “The 

Development of a Detailed Chemical Kinetic 

Mechanism for Di-isobutylene and Comparison to 

Shock Tube Ignition Times”, submitted to ThirtyFirst International Symposium on Combustion, 2005. 

13. Westbrook, C.K., Pitz, W.J. and Curran, H.J., 

“A Chemical Kinetic Modeling Study of the Effects 

of Oxygenated Hydrocarbons on Soot Emissions from 

Diesel Engines”, submitted to Journal of Physical 

Chemistry A, 2005. 

75 
Fuels Technologies FY 2005 Progress Report 

III.3 Improving Ethanol Life Cycle Energy Efficiency by Direct Combustion of 

Wet Ethanol in HCCI Engines 

Salvador M. Aceves (Primary Contact), Joel Martinez-Frias, Daniel L. Flowers, Bruce Buchholz 

Lawrence Livermore National Laboratory 

PO Box 808, L-644 

Livermore, CA 94551 

DOE Team Lead: Stephen Goguen 

Objectives 

• Demonstrate the possibility of using wet ethanol as a fuel for homogeneous charge compression ignition 

(HCCI) engines. 

• Quantify the benefit of directly using wet ethanol on the overall energy balance for ethanol. 

Approach 

• Analyze an HCCI engine system that can be used to evaporate and successfully combust wet ethanol at 

high water concentration (50% by volume or higher). 

• Analyze the overall energy balance for ethanol to determine the energetic cost of every step in ethanol 

manufacture and processing. 

• Analyze different ethanol-water compositions as fuel for HCCI engines to minimize the need for 

distillation and dehydration. 

Accomplishments 

• Conducted an analysis of an HCCI engine system that can work on highly hydrated ethanol while 

delivering high efficiency and low emissions. 

• Performed an evaluation of energy needs for ethanol processing and production. 

• Calculated energy use in distillation as a function of the final ethanol-water composition of the distilled 

mixture. 

Future Directions 

• Experimental demonstration: Modify the fueling system in an existing HCCI engine to demonstrate 

efficient and clean operation on wet ethanol. 

• Use of other marginal, low-grade fuels: Evaluate the utilization of other marginal fuels that can only be 

successfully utilized with HCCI engines, such as trash gas (natural gas with high concentration of carbon 

dioxide or other inert impurities). 

• Analysis of fuel additives: Evaluate whether it is practical to generate HCCI additives (secondary fuels) 

onboard a vehicle to successfully control the engine. 

Introduction 

Dependence on foreign oil and climate 

destabilization are very serious issues that threaten 

the economy and environment. Ethanol has been 

promoted as a domestically produced biofuel that can 

reduce dependence on foreign oil as well as CO2 

emissions. However, a lively debate exists on the 

actual benefits of ethanol production and 

consumption. Ethanol critics have reported that up to 

70 percent more energy is required to produce 

ethanol than the energy it contains [1]. 

76 
Fuels Technologies

Environmental consequences of ethanol production, 

such as soil degradation, have also been described 

and quantified. The high cost of ethanol production 

has also been criticized, and it is typically recognized 

that ethanol production is dependent on government 

subsidies to be competitive. Ethanol utilization is 

also promoted through legislation that mandates the 

use of oxygenated and alternative fuels. 

The energy balance of ethanol has been studied 

in considerable detail by multiple researchers. 

Recent publications [2,3] have reported a slight 

energetic advantage from producing and using 

ethanol from corn (Figure 1). The net gain in making 

ethanol from corn is estimated at only 21% of the 

total energy of ethanol and coproducts, and the 

remaining 79% of the energy is spent in different 

stages of the process. New technologies that 

improve the ethanol energy balance may help in 

delivering the ethanol promise of improved energy 

security and reduced global warming. 

Approach 

A possibility for improving the energy balance of 

ethanol is to develop new utilization techniques that 

may allow a reduction in the processing necessary for 

converting ethanol to a useful form. Figure 1 shows 

that the biggest fraction of the energy necessary for 

making ethanol is spent in distillation and 

dehydration (37% of the total energy in ethanol and 

co-products). It is therefore clear that substantial 

improvement in the energy balance of ethanol can be 

obtained by using wet ethanol directly, possibly with 

only partial distillation as necessary, and with no 

dehydration. While many applications may demand 

neat ethanol, finding a practical application for wet 

ethanol may make the energy balance of ethanol 

much more attractive. 

A new option for prime mover in transportation 

and stationary applications is HCCI engines. 

Automobile and engine manufacturers are interested 

in HCCI engines due to their potential for high 

efficiency and low emissions. HCCI combustion is 

fundamentally different from combustion in sparkignited (SI) engines and diesel engines. HCCI 

combustion is a thermal autoignition of a premixed 

fuel-air mixture, with no flame propagation (as in SI 

engines) or mixing-controlled combustion (as in 

 FY 2005 Progress Report 

Figure 1. Net energy balance for ethanol. The full circle 

represents the energy of ethanol and 

coproducts. The figure shows energy 

consumption in all stages of ethanol production 

from corn, as a percent of the heating value of 

ethanol and coproducts. The energy that 

remains after accounting for all the energy 

consumption is the net energy gain, and it has 

two components: net energy in the ethanol and 

net energy in the coproducts. 

diesel engines) [4]. HCCI engines are intrinsically 

fuel-flexible. Any fuel can be used as long as it can 

be evaporated and then heated by compression to a 

temperature high enough for autoignition 

(approximately 1100 K [5]). The operating limits for 

HCCI are therefore set by the requirement to 

evaporate the fuel and not by the need to propagate a 

flame across the combustion chamber. Also, fuel 

evaporation can be done outside the engine in a 

vaporizer heated by exhaust gases so that the cooling 

effect of water vaporization does not have a negative 

effect on ignition, as it does in a diesel engine. 

Water-ethanol mixtures can therefore be burned in an 

HCCI engine that cannot be burned in either diesel or 

SI engines. 

Results 

We have conducted a detailed thermodynamic 

analysis of an HCCI engine running on wet ethanol. 

The engine and heat recovery system is shown in 

Figure 2 and consists of a regenerator and a vaporizer 

in addition to the typical engine system components 

(turbocharger, catalytic converter). The purpose of 

this work is to determine the maximum concentration 

of water in ethanol that can be used while 

maintaining high performance in the HCCI engine. 

77 
Fuels Technologies

Figure 2. Schematic of the HCCI engine system 

operating on wet ethanol. The numbers in the 

figure show pressures and temperatures for 

operation with a 35-65% volumetric mixture of 

ethanol and water. 

The analysis indicates that a 35% ethanol-water 

mixture by volume can sustain efficient combustion 

in an HCCI engine. Figure 2 shows the 

thermodynamic conditions at all points in the HCCI 

engine system using 35% ethanol as a fuel. The 

compressor delivers air at 300 kPa and 444 K. The 

air temperature is further increased at the regenerator 

by exchanging heat with the exhaust gases. This hot 

air (727 K) is mixed with the wet ethanol in the fuel 

vaporizer, cooling down as the fuel and water 

evaporate. The mixture of ethanol, steam, and air at 

300 kPa and 412 K enters the HCCI engine. The 

charge mixes with the hot residual gases and the 

temperature of the gases in the combustion chamber 

at the beginning of the compression stroke increases 

to 420 K. After combustion, exhaust gases enter the 

catalytic converter at 870 K and leave the catalytic 

converter at 916 K due to combustion of unburned 

hydrocarbons and CO in the catalyst. Gases from the 

catalytic converter (215 kPa and 916 K) go to the 

inlet port of the turbine. The turbine provides all the 

work needed for the compressor to increase the inlet 

pressure to the desired level (300 kPa, in this case). 

After circulating through the turbine, the exhaust 

gases exchange heat with the intake air in the 

regenerator and they leave the system at ambient 

pressure and 562 K. The engine system model 

predicts a 38.7% brake thermal efficiency for the wet 

ethanol HCCI engine. Emissions of NOx are 

predicted at 1.6 parts per million, low enough to meet 

 FY 2005 Progress Report 

any existing or oncoming standards for stationary 

and transportation applications. 

The wet ethanol HCCI engine combines high 

efficiency and low emissions, with the additional 

advantage of considerably improving the energy 

balance for ethanol. The HCCI engine on wet 

ethanol is more efficient than typical SI engines, 

which are limited to ~35% peak brake thermal 

efficiency due to the low compression ratio of SI 

engines necessary to avoid knock [6]. Diesel engines 

are more efficient, but they have high emissions of 

NOx that restrict their applicability to markets 

without strict emissions standards. 

Finally, it is important to determine how the use 

of wet ethanol affects the overall energy balance of 

ethanol production and utilization. Figure 1 shows 

that the net energy balance of ethanol is positive but 

small, with only 21% net energy gain, and 15% of 

this coming from coproducts. Being able to use 

ethanol at 35% volume fraction (14.3% mole 

fraction) considerably reduces the energy required 

for ethanol distillation, from 23% of the total energy 

in ethanol and coproducts to only 3%. The energy 

required for dehydration is reduced from 14% to 

zero, as use of wet ethanol avoids the need for any 

dehydration. The final energy balance for wet 

ethanol is shown in Figure 3. The figure shows that 

using ethanol at 35% volume concentration increases 

the ethanol net energy gain from 6% to 40%. Total 

net energy gain (including coproducts) is now 55%, 

showing a much more favorable energy balance for 

ethanol. It is considered that wet ethanol utilization 

in an HCCI engine may be a path to improve the 

energy balance of ethanol, contributing to climate 

stabilization and improving energy security. 

Conclusions 

We have conducted an analysis that indicates 

that direct combustion of wet ethanol in a 

homogeneous charge compression ignition (HCCI) 

engine can result in a considerable improvement in 

the energy balance for ethanol. HCCI engines are a 

relatively new technology in which combustion 

occurs due to global autoignition of the fuel and air 

mixture. Combustion in HCCI engines is limited by 

the need to evaporate the fuel, and not by the need to 

propagate a flame across the combustion chamber (as 

78 
Fuels Technologies

Figure 3. Net energy balance for ethanol, considering 

that ethanol is used as a 35-65% mixture of 

ethanol and water. The figure shows energy 

consumption in all stages of ethanol production 

from corn, as a percent of the heating value of 

ethanol and coproducts. The energy that 

remains after accounting for all the energy 

consumption is the net energy gain, and it has 

two components: net energy in the ethanol and 

net energy in the coproducts. 

in a spark-ignited engine). Therefore, it is expected 

that HCCI engines can run on wet ethanol with high 

concentration of water. Considering that much of the 

energy required for processing the ethanol is spent in 

distillation and dehydration, direct use of wet ethanol 

in an HCCI engine considerably shifts the energy 

balance in favor of ethanol. 

Special Recognitions & Awards/Patents 

Issued 

1. Salvador M. Aceves invited to deliver a seminar at the 

SAE 2005 HCCI symposium, September 2005, Lund, 

Sweden. 

2. Controlling and Operating Homogeneous Charge 

Compression Ignition (HCCI) Engines, 

Daniel L. Flowers, United States Patent 6,923,167, 

August 2, 2005 

FY 2005 Publications/Presentations 

1. Analysis of Homogeneous Charge Compression 

Ignition (HCCI) Engines for Cogeneration 

Applications, Salvador M. Aceves, Joel MartinezFrias, Gordon M. Reistad, Proceedings of the ASME 

Advanced Energy Systems Division, 2004, Accepted 

for Publication, Journal of Energy Resources 

Technology. 

 FY 2005 Progress Report 

2. A Fully Integrated CFD and Multi-zone Model with 

Detailed Chemical Kinetics for the Simulation of 

PCCI Engines, Aristotelis Babajimopoulos, Dennis N. 

Assanis, Daniel L. Flowers, Salvador M. Aceves, and 

Randy P. Hessel, International Journal of Engine 

Research, Vol. 6, pp. 497-512, 2005. 

3. Improving Ethanol Life Cycle Energy Efficiency by 

Direct Combustion of Wet Ethanol in HCCI Engines, 

Joel Martinez-Frias, Salvador M. Aceves, Daniel L. 

Flowers, Paper IMECE2005-79432, Proceedings of 

the ASME International Mechanical Engineering 

Congress and Exhibition, 2005. 

4. Development and Testing of a 6-Cylinder HCCI 

Engine for Distributed Generation, Joel MartinezFrias, Daniel Flowers, Salvador M. Aceves, Francisco 

Espinosa-Loza, Robert Dibble, Paper ICEF2005­

1342, Proceedings of the 2005 Fall Technical 

Conference, ASME Internal Combustion Engine 

Division, October 2005. 

5. Experimental and Kinetic Investigation of Effect of 

Fuel on Ion Sensor Signal to Determine Combustion 

Timing in HCCI Engines, Parag Mehresh, Jason 

Souder, Daniel Flowers, Uwe Riedel, Robert W. 

Dibble, International Journal of Engine Research, 

Vol. 6, pp. 465-474, 2005. 

6. Effect of the Di-Tertiary Butyl Peroxide (DTBP) 

Additive on HCCI Combustion of Fuel Blends of 

Ethanol and Diethyl Ether, J. Hunter Mack, Daniel L. 

Flowers, Bruce A. Buchholz, Robert W. Dibble, SAE 

paper 2005-01-2135. 

7. Source Apportionment of Particulate Matter from a 

Diesel Pilot-Ignited Natural Gas Fuelled Heavy Duty 

DI Engine, H. L. Jones, G. McTaggart-Cowan, 

S. N. Rogak, W. K. Bushe, S. R. Munshi, 

B. A. Buchholz, SAE paper 2005-01-2149. 

8. Using Carbon-14 Isotope Tracing to Investigate 

Molecular Structure Effects of the Oxygenate Dibutyl 

Maleate on Soot Emissions from a DI Diesel Engine, 

B. A. Buchholz, C. J. Mueller, A. Upatnieks, 

G. C. Martin, W. J. Pitz, and C. K. Westbrook, 

SAE Paper No. 2004-01-1849. 

9. Investigation of HCCI Combustion of Diethyl Ether 

and Ethanol Mixtures Using Carbon 14 Tracing and 

Numerical Simulations, J. Hunter Mack, Daniel L. 

Flowers, Bruce A. Buchholz, Robert W. Dibble, 

Proceedings of the Combustion Institute, Vol. 30, 

2004. 

10. Measuring the Effect of Fuel Structure and Blend 

Distribution on Diesel Emissions Using Isotope 

Tracing, B. A. Buchholz, R. W. Dibble, C. J. Mueller, 

A. S. Cheng, Proceedings of the Western States 

Section of the Combustion Institute, Davis, CA, 

March 2004. 

79 
Fuels Technologies FY 2005 Progress Report 

11. Tracing Fuel Component Carbon in the Emissions 

from Diesel Engines, B. A. Buchholz, C. J. Mueller, 

G. C. Martin, A. S. Cheng, R. W. Dibble, 

B. R. Frantz, Nucl. Instrum. Methods Phys. Res. 

Sect. B, Vol. 223-4, 837-841, 2004. 

12. Analysis of Premixed Charge Compression Ignition 

Combustion with a Sequential Fluid MechanicsMultizone Chemical Kinetics Model, Salvador M. 

Aceves, Daniel L. Flowers, Francisco Espinosa-Loza, 

Aristotelis Babajimopoulos, Dennis Assanis, SAE 

Paper 2005-01-0115, SAE Transactions, 2005. 

13. A Detailed Chemical Kinetic Analysis of Low 

Temperature Non-Sooting Diesel Combustion, 

Salvador M. Aceves, Daniel L. Flowers, SAE Paper 

2005-01-0923, SAE Transactions, 2005. 

14. Spatial Analysis of Emissions Sources for HCCI 

Combustion at Low Loads Using a Multi-Zone 

Model, Salvador M. Aceves, Daniel L. Flowers, 

Francisco Espinosa-Loza, Joel Martinez-Frias, 

John E. Dec, Magnus Sjöberg, Robert W. Dibble and 

Randy P. Hessel, SAE Paper 2004-01-1910, SAE 

Transactions, Journal of Fuels and Lubricants, 2004. 

15. Analysis of the Effect of Geometry Generated 

Turbulence on HCCI Combustion by Multi-Zone 

Modeling, Salvador M. Aceves, Daniel L. Flowers, 

Francisco Espinosa-Loza, Joel Martinez-Frias, 

Magnus Christensen, Bengt Johansson, Randy Hessel, 

SAE Paper 2005-01-2134. 

16. Thermal Management for 6-Cylinder HCCI Engine: 

Low Cost, High Efficiency, Ultra-Low NOx Power 

Generation, Joel Martinez-Frias, Daniel Flowers, 

Salvador M. Aceves, Francisco Espinosa-Loza, 

Robert Dibble, Paper ICEF2004-930, Proceedings 

of the 2004 Fall Technical Conference, ASME 

Internal Combustion Engine Division, October 2004. 

17. The Use of Hydrogen Combustion for Power 

Generation, D. Walther, C. Fernandez-Pello, and 

R. Dibble, S. Aceves and D. Flowers, Paper 

AIAA-2005-5753, 3rd International Energy 

Conversion Engineering Conference and Exhibit, 

San Francisco, California, Aug. 15-18, 2005. 

References 

1. Pimentel, D., 2001, “The Limits of Biomass Energy,” 

In Encyclopedia of Physical Science and Technology, 

Academic Press, Vol. 2., 3rd ed., pp. 159-171. 

2. Shapouri, H., Duffield, J. A., and Wang, M., 2003, 

“The Energy Balance of Corn Ethanol Revisited,” 

Transactions of the ASAE, Vol. 46(4), pp. 959-968. 

3. Shapouri, H., Duffield, J. A., and Graboski, M. S., 

1995, “Estimating the Net Energy Balance of Corn 

Ethanol,” USDA Economic Research Service report 

AER-721, Washington, D.C. 

4. Epping, K., Aceves, S.M., Bechtold, R.L., and 

Dec, J.E., 2002, “The Potential of HCCI Combustion 

for High Efficiency and Low Emissions,” SAE Paper 

2002-01-1923. 

5. Aceves, S. M., Flowers, D. L., Westbrook, C. K., 

Pitz, W., Smith, J.R., Dibble, R. W. Christensen, M., 

and Johansson, B., 2000, “A Multi-Zone Model for 

Prediction of HCCI Combustion and Emissions,” 

SAE paper 2000-01-0327. 

6. Aceves, S. M., Martinez-Frias, J., and Reistad, G. M., 

2004, “Analysis of Homogeneous Charge 

Compression Ignition (HCCI) Engines for 

Cogeneration Applications,” Paper IMECE 

2004-62371, Proceedings of the ASME International 

Mechanical Engineering Congress & Exposition, 

Anaheim, CA. 

80 
Fuels Technologies FY 2005 Progress Report 

III.4 Fuels for Diesel HCCI Engines 

Joshua D. Taylor 

National Renewable Energy Laboratory 

1617 Cole Blvd. MS#1633 

Golden, CO 80401 

DOE Team Lead: Stephen Goguen 

Subcontractors:

Volvo Powertrain (Mack Trucks), Hagerstown, Maryland

Objectives 

• Identify favorable physical properties of synthetic fuel surrogates in homogeneous charge compression 

ignition (HCCI) engines. 

• Quantify the effects of fuel ignition quality and volatility on emissions and efficiency in an HCCI engine. 

Approach 

• Design a matrix of test fuels of varying ignition quality and boiling range. 

• Develop an HCCI engine test platform with a flexible valvetrain and exhaust gas recirculation (EGR) 

capabilities to test fuels. 

• Investigate each test fuel in the HCCI engine test platform to quantify effects of fuel properties on 

emissions and efficiency. 

Accomplishments 

• Quantified ignition quality versus temperature using the Ignition Quality Tester (IQTTM) for the base fuel 

and a matrix of four paraffinic fuels representing 3 boiling ranges and 3 derived cetane number (DCN) 

levels. 

• Achieved very clean HCCI combustion with brake-specific NOx emissions of 0.02 g/bhp-hr and 

undetectable levels of smoke for certain fuels and operating conditions. 

Future Directions 

• No further subcontracted work will occur under this project. 

• This engine was loaned to the National Renewable Energy Laboratory (NREL) and will be set up at the 

ReFUEL Laboratory for continued testing of fuels for HCCI. 

• A similar project on a light-duty HCCI engine will be conducted over the next fiscal year in collaboration 

with the Coordinating Research Council. 

Introduction 

Homogeneous charge compression ignition 

(HCCI) engines have the potential to achieve very 

low pollutant emissions with diesel-like engine 

efficiency. It is likely that future compression 

ignition direct injection (CIDI) engines will employ 

HCCI combustion for at least part of their operating 

range. However, conventional diesel fuel is a poor 

fuel for HCCI combustion, largely due to its low 

volatility and high ignition quality. Other fuels with 

differing physical properties may be better suited for 

HCCI combustion, while still maintaining adequate 

CIDI combustion properties so the fuel could be used 

in a mixed-mode engine. The goal of this project 

was to investigate a matrix of fuels with varying 

81 
Fuels Technologies

volatility and ignition quality to identify how these 

properties can improve HCCI performance in a 

heavy-duty (diesel) engine. 

Approach 

The overall approach was to develop a matrix of 

fuels and test them on a sophisticated HCCI engine 

platform. The matrix of fuels was designed to 

include three levels of ignition quality and three 

boiling ranges. The ignition quality was specified by 

cetane number for the purposes of designing the 

matrix, but ignition quality was measured versus 

temperature using the IQTTM. The fuel matrix 

included a base fuel (EPA Certification fuel) and four 

mixtures of straight-chain and branched alkanes. 

Using mixtures of normal and iso-paraffins, we could 

vary the ignition quality independently from the 

boiling range by changing the relative proportions. 

These mixtures also minimize any other variations of 

physical properties among the test fuels. Figure 1 

shows the boiling ranges and cetane levels of the 

fuels used. 

The matrix of fuels was tested in a heavy-duty 

Mack 12L engine equipped with Sturman Industries’ 

Hydraulic Valve Actuation (HVA) system, shown in 

Figure 2. The Sturman HVA system allows 

flexibility in the valve control, which enables internal 

(hot) EGR and Miller cycle operation (variable 

effective compression ratio). In this study, we chose 

to conduct a parametric study of each fuel operating 

Figure 1. Ignition Quality and Boiling Range of the Test 

Fuels 

 FY 2005 Progress Report 

in HCCI mode at one operating point of 1200 rpm 

and 2 bar brake mean effective pressure (BMEP). 

This modest load condition was chosen because 

HCCI combustion was achievable using the 

conventional diesel fuel under all conditions tested. 

The parametric study included two levels of 

compression ratio, external EGR, boost, and 

injection timing. No control over start of reaction 

timing was employed in this study. 

Results 

The ignition delay was measured as a function of 

charge temperature for each of the test fuels, and the 

results are shown in Figure 3. The temperature 

dependence of the ignition delay differs for each of 

the fuels in the matrix. For example, two of the test 

fuels (Fuel #3 and Soltrol 170) have a DCN of 39 but 

have different boiling ranges and degrees of 

branching. The IQTTM measurements show that 

ignition delay of Fuel #3 has a higher dependence on 

temperature (steeper slope) than that of Soltrol 170. 

This is because of the higher normal paraffin content, 

since isoalkanes have lower activation energy for 

ignition than normal alkanes. Similarly, the 

certification fuel and Fuel #5 have the same DCN of 

46 but show different temperature dependence. 

Since the composition of the cert fuel is not as well 

defined, it is difficult to describe the reason for this 

on a molecular level. However, we can assume that 

aromatics and naphthenes in the certification fuel 

contribute to the higher activation energy than the 

(primarily) isoalkanes in Fuel #5. 

Figure 2. Mack 12L Engine Equipped with Sturman 

HVA System 

82 
Fuels Technologies FY 2005 Progress Report 

In the initial stages of testing, two methods to EGR was not included in our parametric study as it 

vary the start of reaction were tested using the would overly advance ignition. 

Sturman HVA system. In the first method, the 

effective compression ratio was varied using either 

early or late intake valve closing. Start of reaction is 

retarded by reducing the effective compression ratio, 

as expected. In comparing the two means of 

achieving reduced compression ratio (early or late 

intake valve closing), we found that early intake 

valve closing was a better method. When late intake 

valve closing is employed, charge air is introduced 

into the cylinder during intake (where it heats up 

from the cylinder liner) and then is pushed back into 

the intake manifold at the beginning of the 

compression stroke. Over time, the temperature in 

the intake manifold increases, resulting in a higher 

initial charge temperature. This higher initial charge 

temperature advances HCCI ignition further and is 

therefore a less desirable method (for these fuels). 

The second set of experiments was investigating the 

effect of internal EGR by closing the exhaust valve 

late. Internal EGR causes two competing effects on 

start of reaction. Dilution of charge air with exhaust 

should retard ignition, whereas increasing charge 

temperature should advance ignition. We found that 

the charge temperature effect dominated, and 

increasing internal EGR advanced start of reaction. 

Since during HCCI testing start of reaction typically 

occurred significantly before top dead center, internal 

Parametric HCCI testing at a single operating 

point of 1200 rpm and ~2 bar BMEP included two 

EGR levels (0 and 45%), two boost levels (1.0 and 

1.3 bar), two compression ratios (17:1 and 15:1), and 

two injection timings (-66° and -76°). Each fuel was 

tested at all 16 combinations of these four 

parameters. At each test point, emissions of CO, 

hydrocarbons, NOx, and smoke were measured. 

Additionally, fuel consumption and ignition timing 

(reported as CA50 crank angle at 50% heat release) 

were measured. 

One of the main results from this testing was that 

NOx emissions primarily depend on ignition timing 

(CA50) for a particular operating point. Figure 4 

shows brake-specific NOx emissions versus CA50 

for two operating points. All five fuels fall on an 

exponential curve of brake-specific NOx versus 

CA50 for all 16 points. The ignition timing depends 

primarily on derived cetane number. So given that 

NOx emissions depend on ignition timing, fuels that 

allow for ignition close to top dead center perform 

best in this HCCI engine. Another important 

observation from Figure 4 is that reducing effective 

compression ratio delays ignition, but does not 

improve brake-specific NOx emissions. This is 

Figure 3. Ignition Delay Versus Temperature for the Test 

Fuels 

Figure 4. NOx Emissions at Two Compression Ratios for 

the Test Fuels 

83 
Fuels Technologies FY 2005 Progress Report 

because closing the intake valve early reduces the 

quantity of charge air trapped in the cylinder. The 

result is a richer overall mixture and a higher local 

peak temperature. So although Miller cycle 

operation shifts the ignition timing toward top dead 

center, it is not an effective way to achieve very low 

NOx emissions. 

Other results from this project are summarized in 

the following bulleted list: 

• Increasing EGR level was the most effective way 

to achieve very low NOx emissions and shift 

CA50 toward top dead center (see Figure 5). 

• Fuel consumption generally improved as ignition 

timing moved toward top dead center. 

Figure 5. NOx Emissions at Two EGR Levels for the 

Test Fuels 

Conditions with low boost and high EGR 

showed the best fuel consumption. 

• Fuel consumption was generally poor relative to 

conventional CIDI combustion. This was likely 

due to the unit injectors used, which are not 

optimal for HCCI injection. Over time, 

significant fuel quantities were detected in the 

lube oil. However, several operating points with 

certain fuels had comparable brake-specific fuel 

consumption to CIDI operation with 

significantly reduced NOx emissions. 

• Hydrocarbon emissions decrease with increasing 

EGR and are higher for fuels with higher 

volatility. 

Conclusions 

• Ignition timing is the best indicator for emissions 

in HCCI combustion. Fuels that allow ignition 

timing close to top dead center for the largest 

operating range will allow for the widest range of 

HCCI operation in a mixed-mode engine. 

• Fuels with lower ignition quality than 

conventional diesel fuel perform better in HCCI 

modes due to their resistance to early ignition. 

• Miller cycle operation improves ignition timing, 

but does not improve NOx emissions due to 

reduced charge air. EGR is a more effective 

means of controlling start of reaction and 

reducing NOx emissions. 

FY 2005 Publications/Presentations 

1. “HCCI with Synthetic Fuels of Varying Boiling 

Range and Ignition Quality” presented at DOE 

Fuels Program Merit Review. Golden, CO, 

March 7-9, 2005. 

2. “Fuels Ignition Chemistry and Fuel Challenges for 

HCCI Engines” presented at National Reseach 

Council – Canada. Ottawa, Canada, April 19, 2005. 

84 
Fuels Technologies FY 2005 Progress Report 

III.5 Fuel Effects on Gasoline-Based HCCI Performance and Emissions 

Bruce G. Bunting 

Oak Ridge National Laboratory 

Fuels, Engines, and Emissions Research Center 

2360 Cherahala Blvd. 

Knoxville, TN 37932 

DOE Team Lead: Stephen Goguen 

Subcontractors: 

AVL Powertrain, Inc., Plymouth, Michigan 

Battelle, Columbus, Ohio 

Objectives 

• Quantify the effects of fuel properties on homogeneous charge compression ignition (HCCI) combustion 

relative to ignition and combustion characteristics, emissions, and fuel efficiency. 

• Define combustion characteristics of a selected HCCI engine platform to provide a baseline for continuing 

fuels evaluations. 

• Demonstrate the potential for fuel economy improvement from a combination of advanced combustion, 

engine controls, and fuel properties. 

Approach 

• Select research subcontractor with appropriate HCCI engine to maximize experimental results early in the 

project. 

• Develop partnership with major oil company in order to procure fuels for evaluation and technical support 

in test planning and data interpretation. 

• Evaluate performance of the fuels and correlate results to relevant fuel properties. 

• Launch HCCI engine capability for gasoline and diesel range fuels at Oak Ridge National Laboratory 

(ORNL). 

Accomplishments 

• Established sub-contract relationship with AVL Powertrain and research partnership with ExxonMobil. 

• Demonstrated that spark-augmented HCCI can achieve about 12% fuel economy improvement over 

conventional spark-ignited combustion in back-to-back tests for a simulated driving cycle while achieving 

95% NOx reduction. 

• Determined that spark-augmented HCCI is a valid and useful mode of engine control, distinct from pure 

HCCI. 

• Correlated HCCI performance to fuel chemistry and octane values using an expanded set of fuels supplied 

by ExxonMobil. 

• Installation and conversion of gasoline range HCCI engine utilizing variable compression ratio is nearly 

complete at ORNL. 

Future Directions 

• Construct on-line fuel blending system to enhance research capability and flexibility with HCCI fuels. 

• Commission ORNL research engine for gasoline range HCCI and continue diesel range HCCI studies. 

85 
Fuels Technologies FY 2005 Progress Report 

• Determine detailed chemistry effects of HCCI fuels in addition to bulk property effects such as octane, 

cetane, and volatility. 

• Continue to explore issues of stability and moving between various combustion regimes to determine if 

fuel chemistry can improve HCCI controllability and operating range. 

Introduction 

In HCCI, the fuel and air are pre-mixed prior to 

combustion and ignition is initiated by kinetic 

reactions which occur during the compression stroke. 

Ignition occurs when a threshold temperature is 

reached, and the timing of ignition is controlled by 

setting the cylinder conditions at the start of the 

compression stroke. The cylinder charge of fuel and 

air is also diluted with excess air or with exhaust gas. 

The purpose of this dilution is to lower the peak 

flame temperature to reduce NOx and to eliminate 

rich zones which can generate particulate matter. 

The dilution also helps control ignition by changing 

cylinder conditions during compression and helps 

regulate the rate of burning after combustion begins. 

Fuel economy improvement found in some HCCI 

engines is due to a combination of faster heat release, 

reduced heat transfer, and reduced throttling losses. 

Since the ignition process is kinetically driven, 

fuel properties have a large effect on combustion 

characteristics and timing. Fuel octane 

characteristics regulate the tendency of a fuel to 

ignite in an HCCI engine, and fuel volatility can 

impact fuel mixing and evaporation and the degree of 

homogeneity achieved. Fuel chemistry may have a 

large effect because of the various pre-flame 

reactions required for successful ignition in HCCI. 

Conditions supportive of the compression ignition of 

fuels (mainly temperature) can be brought about 

through combination of a variety of engine 

parameters of temperature, compression ratio, airfuel (A/F) ratio, boost pressure, internal or external 

exhaust gas recirculation (EGR), and supplemental 

ignition assist. Fuel chemistry and properties may 

interact differently depending on the engine 

conditions used to promote ignition. 

Approach 

The experiments discussed in this report were 

run on a single-cylinder research engine located at 

AVL Powertrain, in Plymouth, Michigan, under 

sub-contract to Oak Ridge National Laboratory. 

In current configuration, the engine displaces 500 cc 

with an 11.34 compression ratio. The engine has 

spark ignition and gasoline port fuel injection. The 

engine uses a single intake and single exhaust valve 

with fully flexible hydraulically actuated variable 

valve timing. In the work reported here, HCCI 

ignition is initiated by early exhaust valve closing 

and symmetric late intake valve opening combined 

with spark augmentation to assist ignition. This 

valve control strategy results in the retention of 

exhaust in the cylinder (internal EGR) and increased 

pressure and temperature during compression leading 

to auto-ignition of the fuel charge. 

Results 

This research was begun in FY 2004 and 

continued in FY 2005. An additional 7 fuels were 

blended by ExxonMobil in support of this project and 

evaluated at AVL. Generally, our goal was to 

produce fuels with similar octane values (research 

octane number, RON, or motor octane number, 

MON) to the indolene base fuel with widely varying 

chemistry. Several exploratory fuels were also 

blended, including a primary reference fuel, a highvolatility fuel, and a fuel with 10% ethanol. The 

fuels were blended using combinations of 19 pure 

compounds in the gasoline range. Details of the 

blends are shown in Table 1, and the individual blend 

recipes are given in reference 1. A wide range of 

properties and chemistries were obtained, with some 

dependence between properties. One important 

interdependence is between total paraffins, 

aromatics, and octane sensitivity. Fuels with the 

same RON and MON may behave as if they have a 

different octane value if evaluated at conditions apart 

from the RON or MON rating conditions. HCCI 

engines are expected to represent a significant 

departure from the rating conditions. The engine 

used in this study was shown to be “beyond MON” 

because of the high temperatures used for ignition 

combined with natural aspiration and the relatively 

light loads used in this study. 

86 
Fuels Technologies FY 2005 Progress Report 

Table 1. Fuel Properties and Chemistries for Fuel Blends 

PROPERTY FUEL DESIGNATION 

(components 

in volume%) Indolene-0 

F1 

98-80 

F2 

98-87 

F3 

98-98 

Indolene-1 F4 

PRF80 

F5 VOL F6 P F7 POA Indolene-2 F8 PO F9 PA F10 

EtOH 

RON 96.5 97.4 99.5 96.3 96.6 80 80.1 95.8 95.2 96.6 95.5 94.9 95.9 

MON 88 80.9 86.8 94.5 88.3 80 77.3 85.1 85.2 88 85.6 86.2 85 

sensitivity 8.5 16.5 12.7 1.8 8.3 0 2.8 10.7 10 8.6 9.9 8.7 10.9 

T10 (°C) 55.6 79.3 85.1 98.1 52.2 98.1 36.6 65 69.3 55 69.8 63 58.4 

T50 (°C) 106.7 101.1 97.7 98.1 105.5 98.3 38.2 82.4 86.6 105 94.1 90.3 107.4 

T90 (°C) 160.7 108.5 102.1 98.2 162.2 98.4 43.5 99 102.3 161 97.5 102 162.8 

n-paraffins 6.4 10 5.8 1.5 xx 20 40 0 0 6.2 0 2.2 6.7 

iso-paraffins 29.3 0 49.3 98.5 xx 80 60 30 50 28.2 80.4 56.3 43.4 

cycloparaffins 11.3 10 5 0 xx 0 0 70 0 10.3 0 16.4 0 

total paraffins 66.5 20 60.1 100 67.3 100 100 100 50 66.9 80.4 74.9 50.1 

olefins 5 20 10 0 0.4 0 0 0 25 0.8 19.4 0 20 

aromatics 28.5 60 30 0 32.3 0 0 0 25 32.3 0 25 20 

oxygenates 0 0 0 0 0 0 0 0 0 0 0 0 10 

Each fuel was operated at 5 speed/load 

combinations and at a variety of combustion 

phasings, controlled with early exhaust valve closing. 

Engine variables analyzed include peak cylinder 

pressure (CP), pressure rise rate, combustion 

duration, coefficient of variation in indicated mean 

effective pressure, exhaust closing angle, 50% burn 

point (MFB50), fuel consumption, and emissions. 

Fuel variables included octane numbers, boiling 

point values, and fuel composition. A large number 

of plots and relationships were determined and are 

shown in the references. A typical plot is shown in 

Figure 1, which shows peak combustion pressure vs. 

combustion phasing for the 5 speed/load conditions. 

This type of data contains both speed/load 

information and also fuels information. Statistical 

analysis of this data was carried out by Battelle under 

sub-contact to ORNL because of the complex 

interrelationships of the data and in order to sort out 

the statistical effects from data variability. The 

statistical analysis indicated that the combustion 

variables of combustion duration, peak cylinder 

pressure, and pressure rise rate all correlated to 

octane sensitivity, with higher sensitivity resulting in 

faster, higher-pressure combustion. A higher T50 

Figure 1. Relationship of Peak Cylinder Pressure to 

Combustion Phasing for Each Speed-Load 

Combination 

was also shown to increase hydrocarbon emissions 

slightly, showing a volatility or mixing effect. Fuel 

sensitivity was shown to be the best predictor of 

combustion phasing when normalized to the nominal 

or mid-point combustion phasing from this study. 

87 
Fuels Technologies FY 2005 Progress Report 

Figure 2. Relationship of MFB50 at Nominal Exhaust 

Valve Timing to Fuel Sensitivity for Each 

Speed-Load Combination 

Figure 3. Relationship of Effective Octane Number to 

Compression Temperature at 15 Bar for Fuels 

Showing Conditions for RON and MON Tests 

and for HCCI Engine Operation 

This relationship is shown visually in Figure 2, and 

correlation coefficients for this data ranged from 

-0.46 to -0.80 for each of the speed/load 

combinations. 

In this study, fuel sensitivity was determined 

statistically to be the most important fuel variable for 

correlation to engine performance. Fuel sensitivity 

indicates the response of a fuel to the different 

conditions of the RON and MON rating tests and is 

also an indication of a fuel’s chemical makeup. 

HCCI engines achieve combustion when cylinder 

conditions reach a temperature of ignition for the 

fuel, but this temperature can be reached through 

various combinations of initial pressure, initial 

temperature, and cylinder wall temperature. 

Naturally aspirated HCCI engines such as we used 

achieve combustion through high cylinder 

temperatures and relatively low cylinder pressures. 

This type of operation is classified as “beyond 

MON”. Figure 3 shows how apparent octane number 

varies for our test fuels as a function of temperature 

during compression and indicates that high octane 

sensitivity (slope in these lines) can result in a low 

effective octane number at our operating conditions. 

A low octane number, in turn, indicates easier 

ignition under HCCI combustion. This results in 

faster and more rapid combustion, which are 

characteristics we found in the data. 

Conclusions 

A series of gasoline range fuels encompassing 

both fuel property and fuel chemistry variables have 

been successfully run in a spark-assisted HCCI 

engine using a negative valve overlap with a high 

retained exhaust fraction to trigger HCCI. The 

addition of spark assist to an HCCI engine was useful 

to allow starting, to improve transitions to HCCI, to 

help stabilize HCCI, and to expand the operating 

range of HCCI. Within our ability to determine 

between fuels, octane sensitivity emerged as the 

major fuel variable which correlated to engine 

performance under both fixed combustion phasing 

(MFB50) and fixed compression conditions (exhaust 

valve closing angle). The HCCI engine used in this 

study is characterized as being ‘beyond MON’ due to 

the high compression temperatures and relatively low 

pressures resulting from naturally aspirated operation 

combined with a high retained EGR fraction. This 

condition results in high-sensitivity fuels behaving as 

lower octane fuels, which results in earlier or easier 

ignition and faster combustion. The experimental 

trends combined with the work of others support this 

conclusion. There is still the possibility that some 

other fuel property or chemistry variable may have 

an effect on HCCI combustion. More focused 

experiments and modeling are planned for FY 2006 

to more fully answer this question. 

88 
Fuels Technologies

FY 2005 Publications/Presentations 

1. Bunting, B.G., COMBUSTION, CONTROL, AND 

FUEL EFFECTS IN A SPARK-ASSISTED HCCI 

ENGINE EQUIPPED WITH VARIABLE VALVE 

TIMING, offered for presentation at 2006 SAE 

International Congress, 06P-638. 

2. Bunting, B.G., FUEL CHEMISTRY AND CETANE 

EFFECTS ON DIESEL HCCI PERFORMANCE, 

COMBUSTION, AND EMISSIONS, presentation at 

2005 SAE HCCI Symposium, Lund, Sweden, 9/05. 

3. Bunting, B.G., Wildman, Szybist, Lewis, and Storey, 

FUEL CHEMISTRY AND CETANE EFFECTS ON 

HCCI PERFORMANCE, COMBUSTION, AND 

EMISSIONS, presentation at 2005 DOE DEER 

Conference, 8/05. 

4. Bunting, B.G., EFFECTS OF FUEL COMPOSITION 

AND PROPERTIES IN GASOLINE HCCI AND 

SPARK AUGMENTED HCCI, presentation at 2005 

DOE MOU Review, 2/05. 

5. Bunting, B.G., SPARK ASSISTED LOW 

TEMPERATURE COMBUSTION, presentation at 

2005 Advanced Combustion Engine Merit Review, 

4/05. 

 FY 2005 Progress Report 

6. Bunting, B.G., FUEL EFFECTS ON GASOLINE 

BASED HCCI PERFORMANCE AND 

EMISSIONS, presentation at 2005 Fuels Technology 

Program Merit Review, 3/05. 

7. Szybist, J.P., and Bunting, CETANE NUMBER AND 

ENGINE SPEED EFFECTS ON DIESEL HCCI 

PERFORMANCE AND EMISSIONS, SAE 

2005-01-3723. 

8. Lewis, S.A., Storey, Bunting, and Szybist, PARTIAL 

OXIDATION PRODUCTS AND OTHER 

HYDROCARBON SPECIES IN DIESEL HCCI 

EXHAUST, SAE 2005-01-3737. 

9. Bunting, B.G., GASOLINE FUEL PROPERTY AND 

CHEMISTRY EFFECTS ON SPARK STABILIZED 

HCCI COMBUSTION, seminal presentation to 

Penn State University Department of Energy and 

Geo-Environmental Engineering, 10/05. 

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Fuels Technologies FY 2005 Progress Report 

III.6 Fuel Effects on Diesel-Based Advanced Combustion Regimes 

C. Scott Sluder (Primary Contact), Robert M. Wagner 

Oak Ridge National Laboratory 

2360 Cherahala Boulevard 

Knoxville, TN 37932 

DOE Team Lead: Stephen Goguen 

DOE Technology Development Manager: Kevin Stork 

Objectives 

• Investigate the impacts of petroleum, non-petroleum, and bio-derived diesel fuel properties on the 

emissions from high-efficiency clean combustion (HECC) combustion modes. 

Approach 

• Utilize a Mercedes 1.7L diesel engine at Oak Ridge National Laboratory (ORNL) as a research platform 

equipped with full-pass electronic control. 

• Using production-like hardware and control strategies, transition the engine from normal to advanced 

combustion. 

• Characterize the performance and emissions from the engine when using several fuels. 

• Analyze the resulting data to determine fuels impacts on advanced combustion regimes. 

Accomplishments 

• Showed that fuels from a variety of feedstocks (oil-sands, petroleum, and vegetable oil) do exhibit HECC 

behavior at a similar range of engine output and speed. 

• Showed that fuel properties within the limited range studied do not significantly expand the load/speed 

operating regime for HECC. 

• Showed that there was a strong influence of the fuel properties on both particulate and hydrocarbon 

emissions in HECC modes. 

Future Directions 

• For fiscal year 2006, adopt common fuel matrices with other research programs as appropriate and 

available. Continue to study emissions as a means of furthering the understanding of the performance of 

fuels in advanced combustion modes. 

Introduction 

Diesel-based advanced combustion regimes are 

combustion regimes that result in much lower oxides 

of nitrogen (NOx) and particulate matter (PM) 

emissions than traditional combustion processes. 

They can generally be achieved by reducing the 

quantity of fuel that burns in a hot diffusion flame. 

Most methods focus on reducing the diffusion burn 

by increasing the amount of fuel burned in a 

pre-mixed combustion event. This type of 

combustion generally does not lead to the formation 

of problematic pollutants. Formation of a fuel-lean, 

pre-mixed region inside the fuel jet may be 

influenced by several fuel properties, including the 

oxygen content, viscosity, and boiling range. 

Initiation of combustion inside such a region may 

also be influenced by fuel properties such as the 

cetane number. Hence, utilizing fuel property effects 

may represent a means of improving the combustion 

process if the impacts of these properties can be 

understood. 

90 
Fuels Technologies FY 2005 Progress Report 

Approach 

A Mercedes 1.7-liter diesel engine at ORNL was 

utilized for this study. The engine was fueled with 

three hydrocarbon fuels plus two blends using a 

soybean-based biodiesel fuel. The three petroleumbased fuels were termed fuels A, B, and C, and the 

two oxygenated blends were termed fuels AO and 

CO. Fuel A was an off-the-shelf certification diesel 

fuel. Fuel B was a low-sulfur diesel fuel derived 

from Canadian oil-sands reserves. Fuel C was an 

off-the-shelf low-aromatic, low-sulfur diesel fuel. 

Fuels AO and CO were blends of fuels A and C, 

respectively, that contained 5% by volume soymethyl ester biodiesel. (See Table 1 for additional 

fuel properties.) 

Table 1. Fuel Properties 

Characteristic Fuel A Fuel B Fuel C 

Spec. Gravity 0.8453 0.8377 0.8299 

Sulfur (PPM-wt) 386 8.4 13.2 

Viscosity (cs 40 °C) 2.3 2.27 2.32 

Carbon (wt%) 86.85 86.04 86.14 

Hydrogen (wt%) 13.11 13.78 13.86 

Net Heating Value 

(MJ/kg) 

42.754 42.752 43.142 

Cetane Number 47.3 47.9 49.9 

Aromatics (Vol%) 30.6 15.07 9.0 

Olefins (Vol%) 0.8 2.0 0.3 

Saturates (Vol%) 68.6 82.3 90.7 

Polynuclear 

Aromatics (wt%) 

10.0 0.7 1.3 

Distillation (°C) 

IBP 

T10 

T20 

T30 

T40 

T50 

T60 

T70 

T80 

T90 

T95 

EP 

177 

207 

223 

236 

248 

258 

268 

277 

287 

302 

314 

328 

168 

195 

209 

223 

235 

248 

260 

273 

288 

308 

324 

336 

191 

214 

224 

233 

240 

246 

251 

257 

267 

292 

327 

343 

The engine utilized only production-like 

hardware to achieve HECC. The exhaust gas 

recirculation (EGR) rate was increased to target 

14-15% intake O2 concentration. The fuel injection 

parameters were adjusted to provide a higher fuel rail 

pressure that allowed injection of the fuel charge in 

one short pulse at approximately 6 – 8 crank angle 

degrees before top dead center. The fueling strategy 

was held constant for each of the fuels. The brake 

output of the engine was also very similar given the 

close agreement among the heating values of the 

fuels (within 1% for fuels A, B, and C). 

Results 

Engine Operating Conditions – The results 

showed that fuels A, B, and C could achieve HECC 

conditions at the 1,500 RPM/2.80 bar brake mean 

effective pressure (BMEP) and 2,500 RPM/2.00 bar 

BMEP points, but failed to do so at the 2,000 RPM/ 

2.90 bar BMEP point due to high PM emissions 

despite exhibiting very low NOx emissions. This 

provides an opportunity to compare the fuel effects 

both at conditions where HECC could be achieved 

and at the limits of engine operation for HECC where 

differences in fuel behavior are more likely to be 

significant. The brake engine output and fuel rates 

were held constant from baseline to HECC operation 

at each condition, meaning that the brake engine 

efficiency was not compromised from its baseline 

levels by operation in HECC modes. 

Particulate Emissions – The PM mass emissions 

(from filtration) are shown for each of the three 

engine conditions for each of the 3 fuels (A, B, C) in 

Figure 1. The results are shown in column pairs for 

each fuel, with the baseline condition on the left and 

HECC condition on the right for each fuel. The 

HECC conditions for both the 1,500 RPM point and 

the 2,500 RPM point exhibit lower PM emissions 

than the baseline case for each fuel. The 2,000 RPM 

data show that none of the 3 fuels achieved HECC at 

that condition, since the “HECC” PM emissions are 

higher than baseline. The data show that fuel A had 

the highest PM emissions at baseline and under 

HECC at all conditions. Fuels B and C demonstrated 

lower PM emissions at baseline and under HECC at 

all conditions, with fuel C being the lowest. The data 

at 2,000 RPM show that the PM increase for fuel A 

91 
Fuels Technologies FY 2005 Progress Report 

Figure 1. PM Emissions for Fuels A, B, and C (Normal 

mode is the left column and HECC mode the 

right column of each pair.) 

Figure 3. NOx and THC Emissions for Fuels A, B, and C 

(Normal mode is the left column and HECC 

mode the right column of each pair.) 

Figure 2. PM Emissions for Fuels AO and CO (Normal 

mode is the left column and HECC mode the 

right column of each pair.) 

Figure 4. NOx and THC Emissions for Fuels AO and CO 

(Normal mode is the left column and HECC 

mode the right column of each pair.) 

was highest, while those of fuels B and C were lower 

and comparable to each other. This suggests that 

while none of the fuels achieved HECC at the 2,000 

RPM point, fuels B and C approached HECC more 

closely than did fuel A. Figure 2 shows the PM 

emissions results (from filtration) for the two 

oxygenated fuels, AO and CO. The PM emissions for 

fuel AO are lower than those of fuel A. However, 

oxygenation of fuel C with 5% biodiesel does not 

improve its PM emissions at baseline conditions or 

under HECC conditions. The 2,000 RPM results 

show that oxygenation does allow both fuels to 

approach HECC more closely than the nonoxygenated fuels. In fact, fuel CO exhibits only 

marginally higher PM than did fuel C, perhaps 

indicating a transitional condition very close to 

HECC conditions. 

Unburned Hydrocarbon and NOx Emissions – 

The total hydrocarbon (THC) and NOx emissions for 

the 3 petroleum fuels are shown in Figure 3, with the 

results from the oxygenated fuels in Figure 4. The 

results for the three petroleum fuels show that the 

NOx emissions are not significantly dependent upon 

the fuel. The NOx emissions exhibit a marked 

reduction of more than 70%, with reductions 

approaching 90% at the 1,500 RPM condition. The 

NOx emissions for the oxygenated fuels were 

marginally higher than those for the non-oxygenated 

fuels at baseline conditions. The NOx emissions for 

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Fuels Technologies

the oxygenated fuels were very similar to those of the 

non-oxygenated fuels in the HECC modes. The NOx 

was approximately 25% NO2 in baseline modes. The 

NO2 fraction was observed to increase in the HECC 

modes, achieving fractions as high as 60% at some 

conditions. N2O emissions remained constant at 

baseline levels, demonstrating a dependence upon 

neither the combustion mode nor the fuel. 

THC emissions indicate a dependence upon both 

the combustion mode and the fuel. THC emissions 

generally increase in the HECC modes relative to 

baseline. The rate of increase is dependent upon the 

engine load and speed conditions, with higher speed 

conditions generally showing a smaller (or no) 

increase in THC emissions. The THC emissions 

increase at the 2,000 RPM condition was lower than 

for the 1,500 and 2,500 RPM conditions for all three 

fuels. At each engine speed condition, the THC 

emissions followed the same trend noted for the PM 

emissions. That is, the emissions were highest for 

fuel A and lowest for fuel C in both the baseline and 

HECC modes. In fact, the THC emissions for fuel C 

in the HECC modes at both 1,500 and 2,500 RPM 

were lower than the THC emissions for fuel A in the 

baseline modes. 

Carbon Monoxide Emissions – The CO 

emissions for all 3 of the petroleum-based fuels 

increased in HECC mode compared with baseline, 

with the exception of fuels A and B at the 2,500 RPM 

condition. The CO emissions increase at the 2,000 

RPM condition was lower than at the 1,500 and 

2,500 RPM conditions. The data suggest a trend 

towards lower CO emissions for fuel C compared 

with fuel A, but the increases from baseline to HECC 

mode do not exhibit a strong correlation to the fuel. 

 FY 2005 Progress Report 

The data also suggest that oxygenation of the 

fuels yielded mixed results in terms of CO emissions. 

In general, fuel A benefited from oxygenation while 

fuel C did not, at least in terms of CO emissions. 

Conclusions 

• Fuel properties in the ranges studied with the 

5 fuels reported did not expand the HECC 

operating envelope significantly, but did have 

marginal impacts. 

• Blends of 5% biodiesel with petroleum-based 

fuels were observed to exhibit HECC modes 

similar to those observed without biodiesel 

blending. 

• EGR effects on NOx emissions in HECC modes 

overwhelmed any fuel effects on NOx emissions. 

• Hydrocarbon emissions in HECC modes were 

strongly dependent upon the fuel burned. In 

general, fuels that produced less PM in normal 

modes produced less HC emissions in HECC 

modes. 

• PM emissions in HECC modes were dependent 

upon the fuel burned, but less so than the PM 

emissions in normal modes. 

FY 2005 Publications/Presentations 

1. “Fuel Property Effects on Diesel High-Efficiency 

Clean Combustion,” Presented at the 2005 DOE Fuels 

Technology Program Merit Review. 

2. “Fuel Property Effects on Emissions from HighEfficiency Clean Combustion in a Diesel Engine,” 

Paper in review for publication at the 2006 SAE 

International Congress and Exhibition. 

93 
Fuels Technologies FY 2005 Progress Report 

III.7 Fuel Effects on Diesel-Based HCCI Performance and Emissions 

Bruce G. Bunting (Primary Contact), Sam Lewis, John Storey, Craig Wildman, and Jim Szybist 

Oak Ridge National Laboratory 

Fuels, Engines, and Emissions Research Center 

2360 Cherahala Blvd. 

Knoxville, TN 37932 

DOE Team Lead: Stephen Goguen 

DOE Technology Development Manager: Kevin Stork 

Objectives 

• Quantify the effects of fuel properties on homogeneous charge compression ignition (HCCI) combustion 

relative to ignition and combustion characteristics, emissions, and fuel efficiency. 

• Baseline performance and combustion characteristics of a selected HCCI engine to provide a stable 

platform for continuing fuels evaluations. 

• Demonstrate the potential for fuel economy improvement from a combination of advanced combustion, 

engine controls, and fuel properties. 

• Evaluate alternate fuels such as those containing biodiesel or oil sands derived components for 

performance characteristics. 

Approach 

• Establish HCCI engine capability and acquire diesel range fuels. 

• Evaluate fuel performance in engine tests and correlate results to relevant fuel properties. 

Accomplishments 

• Completed installation and conversion of small diesel engine to HCCI combustion and conducted two fuel 

effects studies for diesel range fuels. 

• Correlated HCCI performance to fuel chemistry and cetane values using commercial diesel fuels, blends of 

diesel secondary reference fuels, and biodiesel fuel. 

Future Directions 

• Determine detailed chemistry effects of HCCI fuels in addition to bulk property effects. 

• Conduct studies to help define performance characteristics of biodiesel blends and effects of cetane 

number on effective load range. 

• Continue to explore issues of stability and moving between various combustion regimes to determine if 

fuel chemistry can improve HCCI controllability and operating range. 

• Interact with Cummins, Inc. and BP regarding fuel effects to achieve high-efficiency and low-emission 

combustion. 

Introduction reactions which occur during the compression stroke. 

Ignition occurs when a threshold temperature is 

In HCCI, the fuel and air are pre-mixed prior to reached, and the timing of ignition is controlled by 

combustion, and ignition is initiated by kinetic setting the cylinder conditions at the start of the 

94 
Fuels Technologies

compression stroke. The cylinder charge of fuel and 

air is also diluted with excess air or with exhaust gas. 

The purpose of this dilution is to lower the peak 

flame temperature to reduce NOx and to eliminate 

rich zones which can generate particulates. The 

dilution also helps control ignition by changing 

cylinder conditions during compression and to 

regulate the rate of burning after combustion begins. 

The improvement in fuel efficiency found in some 

HCCI engines is due to a combination of faster heat 

release, reduced heat transfer, and reduced throttling 

losses. 

Since the ignition process is kinetically driven, 

fuel properties have a large effect on combustion 

characteristics and timing. Fuel cetane 

characteristics regulate the tendency of a fuel to 

ignite in an HCCI engine, and fuel volatility can 

impact fuel mixing, evaporation, and the degree of 

homogeneity achieved. Fuel chemistry may have a 

large effect because of the various pre-flame 

reactions required for successful ignition. 

Conditions supportive of the compression ignition of 

fuels (mainly temperature) can be brought about 

through combination of a variety of engine 

parameters such as temperature, compression ratio, 

air/fuel ratio, boost pressure, internal or external 

exhaust gas recirculation (EGR), and supplemental 

ignition assist. Fuel chemistry and properties may 

interact differently depending on the engine 

conditions used to promote ignition. 

Approach 

The experiments discussed in this report were 

conducted on a single-cylinder research engine 

located at Oak Ridge National Laboratory (ORNL). 

This engine was converted from a single-cylinder 

Hatz industrial diesel engine. The engine was 

modified by lowering the compression ratio from 

20:1 to 10.5:1, by removing the conventional diesel 

injection system, by adding a 6 kW intake air heater, 

and by adding port fuel injection. The port fuel 

injection consists of an ORNL-designed heated 

atomizer which allows port injection of diesel fuel 

and provides a very uniform fuel/air mixture. The 

engine operates un-throttled, and combustion is 

regulated by intake air temperature. Figure 1 shows 

the engine and test rig, and Figure 2 shows details of 

the heated atomizer. Fuels are evaluated by 

 FY 2005 Progress Report 

Figure 1. HCCI Engine and Test Rig 

Figure 2. ORNL Heated Atomizer 

conducting a timing sweep controlled by intake air 

temperature to vary combustion phasing. 

As temperature is increased, timing advances, and 

this advance is limited by maximum rate of cylinder 

pressure rise. As temperature is decreased, timing 

is retarded, and this retard is limited by combustion 

variability. 

Results 

Optimum combustion phasing was shown to 

vary with fuel cetane number. To achieve maximum 

power output, higher-cetane fuels required more 

advanced fuel introduction than lower-cetane fuels. 

Fuels below 40 cetane possessed no low-temperature 

heat release (LTHR), while fuels above 40 cetane 

had increasing amounts of LTHR. Higher-cetane 

fuels also had a longer combustion duration 

(CA 10-90) than low-cetane fuels because of their 

increasing LTHR. Optimal timing and combustion 

duration are shown in Figure 3 as a function of 

cetane number. As timing was retarded for all the 

fuels, hydrocarbon (HC) and CO emissions 

increased, with CO increasing more rapidly for the 

high-cetane fuels. This indicates the sensitivity of 

95 
Fuels Technologies FY 2005 Progress Report 

Figure 3. Relationship of Cetane Number to Optimum 

Combustion Phasing 

LTHR to quenching effects and the generation of 

partial oxidation products during LTHR. NOx was 

low for all fuels in the range of optimal timings 

(below 10 ppm) and increased for all fuels as a 

function of rate of cylinder pressure rise for more 

advanced combustion timing, as shown in Figure 4. 

Increasing fuel aromatic content had a weak effect on 

increasing the rate of cylinder pressure rise, HC 

emissions, and NOx. It appeared that fuels with 

about 40 to 45 cetane number were optimum for 

maximum power output. As cetane number was 

increased from this, it became difficult to control 

combustion phasing late enough. With lower-cetane 

fuels, higher intake temperatures were needed for 

ignition, which tended to drive the engine into knock 

as fuel rate was increased. 

Conclusions 

Results from this study indicate that as cetane 

number increases, the optimum combustion phasing 

advances, low-temperature heat release increases, 

and NOx decreases slightly. Higher cetane resulted 

in a faster rate of cylinder pressure rise and higher 

NOx and HC emissions. Generally, NOx emissions 

were related to the maximum rate of cylinder 

pressure rise. Biodiesel operated differently from the 

petroleum-based fuels, exhibiting higher emissions, 

faster heat release, and less low-temperature heat 

release. All fuels operated successfully at the loads 

used for these experiments, and the heated atomizer 

proved to be a good way to simplify fuel delivery. In 

our mode of engine control, fuel rate is kept constant 

and intake heating is used to control to maximum 

power output. Changing intake air temperature also 

Figure 4. Relationship of NOx to Rate of Cylinder 

Pressure Rise 

changes combustion chamber temperature and fuel 

air ratio. Further defining these effects is a subject 

for future research along with further fuel and fuel 

blend studies. 

FY 2005 Publications/Presentations 

1. Bunting, B.G., FUEL CHEMISTRY AND CETANE 

EFFECTS ON DIESEL HCCI PERFORMANCE, 

COMBUSTION, AND EMISSIONS, presentation at 

2005 SAE HCCI Symposium, Lund, Sweden, 9/05. 

2. Bunting, B.G., Wildman, Szybist, Lewis, and Storey, 

FUEL CHEMISTRY AND CETANE EFFECTS ON 

HCCI PERFORMANCE, COMBUSTION, AND 

EMISSIONS, presentation at 2005 DOE DEER 

Conference, 8/05. 

3. Szybist, J.P., and Bunting, CETANE NUMBER AND 

ENGINE SPEED EFFECTS ON DIESEL HCCI 

PERFORMANCE AND EMISSIONS, 

SAE 2005-01-3723. 

4. Lewis, S.A., Storey, Bunting, and Szybist, PARTIAL 

OXIDATION PRODUCTS AND OTHER 

HYDROCARBON SPECIES IN DIESEL HCCI 

EXHAUST, SAE 2005-01-3737. 

5. Wildman, C.B., and Bunting, A COMPARISON OF 

BIODIESEL COMBUSTION PERFORMANCE 

WITH THAT OF THREE OTHER DIESEL FUELS 

IN A HOMOGENEOUS CHARGE COMPRESSION 

IGNITION ENGINE, offered for presentation at 2006 

ACS Biofuels for Transportation Symposium, 

Atlanta, GA., 4/06. 

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Fuels Technologies FY 2005 Progress Report 

IV Transition to Hydrogen Economy

97
Fuels Technologies FY 2005 Progress Report 

98
Fuels Technologies FY 2005 Progress Report 

IV.1 Advancing Gaseous Fuel Vehicle and Infrastructure Technology 

Richard Parish 

National Renewable Energy Laboratory 

1617 Cole Blvd. 

Golden, CO 80401 

DOE Technology Development Managers: Dennis Smith and David Hamilton 

Subcontractors: 

Clean Vehicle Education Foundation, Acworth, GA 

Cummins Westport Inc., Vancouver, BC, Canada 

Gladstein, Neandross & Associates, LLC, Santa Monica, CA 

John Deere Power Systems, Waterloo, IA 

Mack Trucks Inc., Hagerstown, MD 

Westport Innovations 

Objectives 

• Promote reduction of U.S. petroleum consumption via advancement of gaseous fuel vehicle and 

infrastructure technologies 

• Develop technologies to expedite the transition to the hydrogen-based transportation of the future 

• Reduce emissions of pollutants compared with conventional fuel vehicles 

Approach 

• Engine & Vehicle Platform Development: Develop commercially viable gaseous fuel vehicles (GFVs) that 

compare favorably with conventional counterparts in terms of cost, reliability, performance, and adherence 

to Environmental Protection Agency (EPA) emission standards. 

• Infrastructure Enhancement: Reduce costs and improve availability and reliability of gaseous fuel 

refueling. 

• Hydrogen Transition Technology Development: Develop technologies and infrastructure that exploit the 

synergy between hydrogen and natural gas (NG) vehicles, promoting the transition to hydrogen-based 

transportation. 

• Technology Transfer: Provide technical assistance to GFV adopters and introduce hydrogen technologies. 

Accomplishments 

Engine & Vehicle Platform Development 

• Completed project to develop a Cummins Westport Inc. (Cummins/Westport or CWI) lean-burn 8.9L NG 

engine and integrate it into multiple vehicle platforms* 

• Continued projects to develop and/or integrate the following NG engines: 8.1L John Deere, 

12L Mack/Volvo, and 15L Cummins/Westport* 

• Continued projects to develop 11L Mack/Volvo (variable valve timing) and 8.9L Cummins/Westport NG 

engines** 

• Initiated project to develop a NG stochiometric engine for transit buses** 

(*2007 EPA emission standards; **2010 EPA emission standards) 

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Fuels Technologies FY 2005 Progress Report 

Infrastructure Enhancement 

• Published final safety evaluation report of NG home refueling appliance 

Hydrogen Transition Technology Development 

• Completed evaluation of opportunities to integrate hydrogen into natural gas vehicle (NGV) fueling 

stations of the Interstate Clean Transportation Corridor (ICTC) 

Technology Transfer 

• Held Natural Gas Vehicle Technology Forum (NGVTF) meeting in August 2005 and updated its Web site 

• Held Transit Users Group (TUG) meeting in November 2004 

• Actively participated in California NGV Partnership 

• Provided leadership for codes and standards development 

Future Directions 

• Advance NG engine and vehicle technologies, including the following: 

– High-pressure direct injection (HPDI) 

– Digital camless variable valve timing 

– Three-way catalysts for heavy-duty stoichiometric engines 

– Lean air/fuel ratio, exhaust gas recirculation, and advanced aftertreatment 

– Hybridization of NGVs 

– Variable hydrogen compressed natural gas (HCNG) blend lean-burn engines 

• Develop synergy between NG and hydrogen vehicle and infrastructure technologies 

• Expand partnerships to advance and transfer gaseous fuel technologies; leverage R&D funding with 

additional partners 

Introduction 

The National Renewable Energy Laboratory 

(NREL) advances gaseous fuel vehicle (GFV) and 

infrastructure technology in support of two major 

U.S. Department of Energy (DOE) goals: 1) reduce 

petroleum consumption and 2) provide a transition to 

hydrogen-based transportation. GFVs can also 

reduce emissions of regulated pollutants compared 

with gasoline- and diesel-fueled vehicles. Gaseous 

fuels include natural gas, hydrogen, and hydrogennatural gas blends. 

Approach 

NREL employs an integrated strategy—from 

research to demonstration—to advance technology 

for commercially viable GFVs and related 

infrastructure, primarily for the medium- and heavyduty sectors (Figure 1). These efforts fall into four 

Figure 1. NREL’s Integrated Strategy for Advancing 

Gaseous Fuel Vehicle and Infrastructure 

Technology 

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Fuels Technologies

categories: engine & vehicle platform development, 

infrastructure enhancement, hydrogen transition 

technology development, and technology transfer. 

To leverage resources, NREL forms partnerships 

with industry and government. 

Results 

Engine & Vehicle Platform Development 

NREL carries out most of its engine and vehicle 

platform development as part of the Next Generation 

Natural Gas Vehicle (NGNGV) activity. The 

NGNGV activity is supported by DOE’s 

FreedomCAR & Vehicle Technologies Program, 

South Coast Air Quality Management District 

(SCAQMD), and the California Energy Commission. 

In FY 2005, NREL had eight NGNGV projects 

(Table 1 and Figure 2). 

NREL completed development and vehicle 

integration of a Cummins/Westport 8.9L NG engine 

that complies with the EPA 2007 emissions standards 

(1.2 g/bhp-hr NOx, 0.01 g/bhp-hr PM) for refuse 

trucks. 

NREL continued to integrate three other EPA 

2007-compliant NG engines into various platforms. 

A John Deere 8.1L engine was certified to target 

NOx levels, demonstrated in transit and school bus 

fleets, and is planned to be developed into a 9.0L 

engine to meet 0.2 g/bhp-hr NOx levels in a 

follow-on procurement action. A liquefied natural 

gas (LNG) pump and tank was designed, and 

certification is underway for an EPA 2007-compliant 

15L Cummins/Westport engine for tractor-trailer 

platforms. Finally, an EPA 2007-compliant 

Mack/Volvo 12L engine was integrated into a refuse 

truck platform and is ready for demonstration under a 

follow-on activity funded by SCAQMD. 

NREL also continued to develop NG engines 

capable of achieving EPA 2010 emission standards 

of 0.2 g/bhp-hr NOx and 0.01 g/bhp-hr PM for 

medium- and heavy-duty vehicle applications. 

A Mack/Volvo 11L engine under development uses 

variable valve timing to increase combustion and 

cycle efficiency and decrease emissions. 

A “concept” 8.9L Cummins/Westport engine is now 

operational and ready for demonstration. 

 FY 2005 Progress Report 

Table 1. Next Generation Natural Gas Vehicle Engine & 

Vehicle Platform Development FY 2005 

Projects 

Infrastructure Enhancement 

NREL published a final report about its 

independent safety evaluation of FuelMaker’s home 

refueling appliance (HRA), which is designed to 

refuel compressed natural gas (CNG) vehicles inside 

residential garages. The report is being used to 

educate local code officials during initial deployment 

of the HRA. 

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Fuels Technologies FY 2005 Progress Report 

Figure 2. Next Generation Natural Gas Vehicle Engine & 

Vehicle Platform Development Projects 

Hydrogen Transition Technology Development 

NREL completed a project with Gladstein, 

Neandross & Associates to investigate establishing 

combined hydrogen-NG stations along the Interstate 

Clean Transportation Corridor (ICTC) (Figure 3). 

The ICTC is a network of CNG and LNG stations in 

California and surrounding states. 

ICTC project findings and recommendations 

have been presented in a report for future planning. 

Technology Transfer 

NREL leads DOE’s Natural Gas Vehicle 

Technology Forum (NGVTF) to facilitate 

communication and leverage resources among its 

stakeholders, including those who will play a key 

role in proliferating hydrogen vehicle technology. 

Around 80 people attended the NGVTF meeting held 

August 2-4, 2005, in Washington, DC. Participants 

included representatives of original equipment 

manufacturers, vehicle/infrastructure packagers, 

national laboratories, federal/state/local 

governments, industry/trade associations, 

consultants, utilities, fuel distributors, and fleet 

operators. 

Figure 3. Map of Current Hydrogen Vehicle & Station 

Development Projects with Proposed ICTC 

Hydrogen Demonstration Projects Added 

As part of the NGVTF, NREL leads DOE’s 

Natural Gas Transit Users Group (TUG). A TUG 

meeting was held in November 2004 in Anaheim, 

California, in conjunction with an American Public 

Transit Association Workshop. 

NREL provided leadership and direction for 

codes and standards development related to NGV 

technology development. NREL and its 

subcontractors actively participated in meetings 

hosted by the National Fire Protection Association, 

Society of Automotive Engineers, and the DOE 

Hydrogen Codes & Standards Committee. 

Conclusions 

As much as 800 million gallons of diesel fuel 

could be displaced annually if NGVs replaced diesel 

vehicles in half of all transit buses, school buses, 

refuse trucks, and demand-response vehicles. 

DOE/NREL-sponsored engines are already 

displacing as much as 72 million gallons of diesel 

fuel each year. NG transit buses continue to be the 

single largest niche application (Figure 4), 

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Fuels Technologies

Figure 4. Proportion of U.S. Transit Buses Powered by 

Natural Gas (Source: American Public 

Transportation Association) 

constituting approximately 25% of all new transit 

buses ordered in 2004 (4). TUG remains an effective 

forum for this critical sector. 

Current medium- and heavy-duty NGVs 

typically exhibit lower emissions (particularly NOx) 

compared with their diesel counterparts. NREL has 

developed engines that meet EPA 2007 emissions 

standards and demonstrated those that meet EPA 

2010 emissions standards. Meeting these stringent 

emissions standards promotes the use of NGVs. 

NREL continues to explore synergistic 

opportunities between hydrogen and NG, regarding 

both engine development and fuel infrastructure. 

NREL has investigated combined hydrogen-NG 

fueling stations as a way to expedite the transition of 

a hydrogen-based transportation network. 

FY 2005 Publications 

1. Safety Evaluation of the FuelMaker Home Refueling 

Concept: Final Report http://www.nrel.gov/ 

vehiclesandfuels/ngvtf/pdfs/36780.pdf 

2. Evaluating the Safety of a Natural Gas Home 

Refueling Appliance http://www.nrel.gov/ 

vehiclesandfuels/ngvtf/pdfs/037333ng_refuel.pdf 

 FY 2005 Progress Report 

3. Assisting Transit Agencies with Natural Gas Bus 

Technologies http://www.nrel.gov/vehiclesandfuels/ 

ngvtf/pdfs/037921ng_bus.pdf 

4. Strategy for the Integration of Hydrogen as a Vehicle 

Fuel into the Existing Natural Gas Vehicle Fueling 

Infrastructure of the Interstate Clean Transportation 

Corridor Project http://www.nrel.gov/ 

vehiclesandfuels/ngvtf/pdfs/38720.pdf 

5. Heavy-Duty Waste Hauler with Chemically Correct 

Natural Gas Engine Diluted with EGR and Using a 

Three-Way Catalyst http://www.nrel.gov/ 

vehiclesandfuels/ngvtf/pdfs/38222.pdf 

FY 2005 Presentations 

1. NGNGV Presentation at the Faster Freight-Cleaner 

Air 2004 Conference, December 2004 http:// 

www.nrel.gov/vehiclesandfuels/ngvtf/pdfs/37406.pdf 

2. Alternative Fuels and Systems for Refuse Trucks, 

Presented to the Municipal Waste Management 

Association, March 2005 http://www.nrel.gov/ 

vehiclesandfuels/ngvtf/pdfs/37843.pdf 

3. NGVTF Meeting Presentations, August 2005 

http://www.nrel.gov/vehiclesandfuels/ngvtf/ 

tech_comm_mtg_aug05.html 

References 

1. Energy Information Administration Annual Energy 

Review (U.S. Department of Energy), 2002, 

www.eia.doe.gov/emeu/aer/contents.html. 

2. Transportation Energy Data Book, Edition 23, Oak 

Ridge National Laboratory (U.S. Department of 

Energy), 2001, www-cta.ornl.gov/data/Index.html. 

3. U.S. Environmental Protection Agency Air Pollutant 

Emission Trends Web Site, 2001, www.epa.gov/ttn/ 

chief/trends/index.html. 

4. Assisting Transit Agencies with Natural Gas Bus 

Technologies (U.S. Department of Energy), 2005, 

http://www.nrel.gov/vehiclesandfuels/ngvtf/pdfs/ 

037921ng_bus.pdf. 

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Fuels Technologies FY 2005 Progress Report 

IV.2 Recovery of Natural Gas from Renewable Resources 

James Wegrzyn 

Brookhaven National Laboratory 

Building 815 

Upton, New York 11973 

DOE Technology Development Manager: Dennis Smith 

Subcontractors: 

Mack/Volvo; Allentown, PA 

Acrion; Cleveland, OH 

Air Products; Allentown, PA 

Chart Industries; Burnsville, MN 

Waste Management; Houston, TX 

Objectives 

• Support R&D projects to identify vehicle fuel quality issues when liquefied natural gas (LNG) is produced 

from landfill gas (LFG) which is derived from renewable sources. 

• Develop LNG recovery from LFG technologies in order to displace over 3 million gallons of diesel fuel 

per year per landfill. 

• Address climate change issues by minimizing methane release and improving overall system efficiency by 

integrating LFG collection, clean-up, and liquefaction with LNG storage and delivery. 

Approach 

• Install a 10 gallon per hour process development unit (PDU) at the Burlington, New Jersey, landfill for 

converting LFG into LNG. 

• Produce 10,000 gallons of LNG from LFG for vehicle fuel quality evaluation. 

• Disassemble and analyze for premature failures refuse truck engines that were fueled with LNG derived 

from LFG. 

Accomplishments 

• Performed regularly scheduled commercial collection of refuse using trucks fueled with the 10,000 gallons 

of continuously produced LNG from LFG. 

• Trucks experienced no downtime related to fuel quality issues during the 600-hour road tests. 

• Disassembly and examination of the engines indicated no evidence of premature wear, performance 

degradation, or the presence of compounds that could adversely affect engine operation, durability or 

reliability. 

• Increased LNG production rate from 9.6 gallons per hour to 14.0 gallons per hour by allowing the CO2 

concentration in the LNG to increase while still keeping it below solubility limits. 

Future Directions 

No additional work is currently planned, but the following work could be considered if funds become available 

in the future. 

104 
Fuels Technologies FY 2005 Progress Report 

• Gas separation studies could further improve the 

production rate of LNG from LFG. Figure 1 shows 

a 45.8% increase in production rate by better 

controlling the carbon dioxide and methane 

separation process. 

• A LNG from LFG project costs from $10 to 15 

million dollars. By issuing a $1 million dollar cost 

share request for proposal, DOE could direct this 

activity towards a “no atmospheric methane 

release” strategy in the recovery/use of LNG from 

LFG. 

• Conduct a technical feasibility analysis to 

determine the number of active landfills and related 

refuse handling trucks & equipment in the U.S. that 

are good candidates for this technology. Identify potential project partners for an expanded field test 

or demonstration project. 

Figure 1. Liquid Methane Production Run #1 – 

August 10 to August 15, 2004 

Introduction 

This project reports the first sustained production 

and utilization of liquid methane from landfill gas 

which is derived from renewable resources. (LNG 

from LFG is more accurately referred to as liquid 

methane, since its composition is very low in the 

higher hydrocarbons such as ethane, propane, etc., 

when compared to LNG from pipeline natural gas.) 

Through the process of making LNG, the diluents in 

landfill gas such as CO2 and N2 are removed which 

lower heating value and limit its usefullness to nontransportation applications. The LNG production 

process removes virtually all the contaminants such 

as sulfur oxides associated with landfill gas. By 

making LNG, a low-value fuel is upgraded to an 

ultra-clean high value fuel suitable for transportation 

vehicles and heavy-duty equipment. 

This new achievement in landfill gas processing 

took place at the Rutgers N.J. EcoComplex, located 

adjacent the Burlington County Landfill, Columbus, 

New Jersey. The landfill-derived LNG powered two 

Mack dedicated natural gas-powered refuse trucks 

owned and operated by Waste Management, Inc. 

The trucks saw daily service from the Burlington 

County Landfill to the Fort Dix Army Base and the 

McGuire Air Force Base. Each truck accumulated 

more than 600 hours of service and consumed about 

10,000 gallons of LNG. 

Approach 

Acrion Technologies, Inc. has investigated 

production of liquid methane from landfill gas for 

more than a decade. During the past several years, 

with direction from Brookhaven National Laboratory 

and funding from DOE, these investigations have 

noticeably raised the confidence level of industrial 

stakeholders in the viability of Acrion’s LFG cleanup 

technology. For example, the accomplishments 

listed in this report were a cooperative effort of Mack 

Trucks, Acrion, Waste Management, Air Products, 

Chart Industries, and the Burlington County, N.J., 

EcoComplex. The approach has been guided by 

Acrion’s past successes. In 2001, an independent 

testing lab (Atlantic Analytical Laboratory, 

Whitehouse, N.J.) verified that Acrion’s cleanup 

technology removed halogenated compounds, 

siloxane, sulfur and non-methane organic 

contaminates from landfill gas to levels below one 

part per million (ppm) aggregate (Table 1). At the 

request of Mack Trucks, these results were replicated 

in 2002. In 2003, Acrion designed and installed CO2 

removal and methane liquefaction to its PDU at the 

EcoComplex and first produced liquid methane from 

LFG on May 16, 2003. Upon the successful 

completion of these performance trials, the next step 

was the production of sufficient quantities of liquid 

methane using Acrion’s technology. The goal is to 

operate refuse trucks for 600 hours in order to verify 

no adverse effects on the engines from running on 

LNG from LFG. 

105 
Fuels Technologies FY 2005 Progress Report 

Table 1. Summary of Analytical Testing Performed by Atlantic Analytical Laboratory 

Sample ID Truck Fuel Raw LFG Truck Fuel Truck Fuel 

Sample Date 13 Aug 04 2 Dec 04 2 Dec 04 13 Jan 05 

AAL Number 1352 2527-1rev 2527-2rev 2982 

Test Performed 

Non Condensable Gases 3 3 3 3 

Volatile Hydrocarbons 3 3 3 3 

Siloxanes (by GC/MS) 3 3 

Volatile Sulfur Compounds 3 3 

GC/MS TO-14 Target List 3 3 

GC/MS Non TO-14 Target List 3 3 

Toxic Substances Sub-17 Extended List 3 3 

Analysis Overview 

Methane, CH4 94.05% 57.13% 99.19% 98.55% 

Carbon Dioxide, CO2 0.12% 42.2% ND 480 ppm 

Nitrogen, N2 5.81% 0.43% 0.73% 1.18% 

Siloxanes NA 1.2 ppm ND NA 

Other ND 390 ppm 10 ppm C3 13 ppm C3 

3.2 ppm TX 

Notes: NA not analyzed; ND not detected; TX toluene xylene 

Results 

Two dedicated natural gas refuse haulers ran 

daily service from October 19th, 2004, through 

January 27th, 2005, on LNG from the Burlington 

County Landfill. Each truck accumulated more than 

600 hours engine time and consumed 10,000 gallons 

of LNG. Average fuel consumption in daily refuse 

collection service was about 7.5 gallons liquid 

methane per hour of engine operation. The trucks 

experienced no downtime related to fuel quality 

issues, and the drivers’ comments were positive on 

several accounts: no odor, no smoke and reduced 

noise. LFG typically contains siloxanes that form 

silicates when burned in the combustion chamber, 

resulting in hard silicate plating on exhaust 

components. The silicates will accelerate engine 

wear if siloxanes are not removed from the LFG. 

Disassembly and examination of these engines 

produced no evidence of premature wear, 

performance degradation, or accumulation of 

deposits that could adversely affect engine operation, 

durability or reliability. Chlorinated hydrocarbons 

are also found in LFG that form acids and can attack 

engine bearings. No chlorinated hydrocarbons were 

found in the oils taken from these engines. Finally, it 

should be noted that the engine control system was 

operating as intended. This would suggest that there 

was no contamination to the fuel system or other 

sensor systems from using the processed LFG. 

Following the inspection, Mack engineers then 

reassembled the engines such that they retained the 

same warranty as new natural gas engines. 

Conclusions 

The first objective of demonstrating vehicle fuel 

quality of LNG from LFG was met. These results, 

when combined with diesel fuel prices exceeding 

$2.00 a gallon, have created a market-driven interest 

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Fuels Technologies

in using landfill gas derived from renewable 

resources to power LNG vehicles. The metric of 

“vehicles converted to alternative fuels” has been 

used in the past to assess the viability of DOE’s 

alternative fuel program. The future metric is likely 

to be petroleum displaced. The conversion of 300 

landfills to produce LNG can result in the 

displacement of over 1 billion gallons of diesel 

yearly. DOE also has the responsibility to see that 

this emerging LFG to LNG technology reduces and 

 FY 2005 Progress Report 

doesn’t add to climate change concerns. Designs of 

LNG refueling stations must take into account that 

LNG is a “use it or lose it” fuel, and the atmospheric 

venting of methane by either the vehicle or refueling 

station has to be addressed before this technology can 

be successfully commercialized. Lastly, LNG from 

LFG has international appeal. DOE can, through its 

existing international partnerships, further develop 

and transfer a sustainable energy technology that is 

environmentally acceptable. 

107 
Fuels Technologies FY 2005 Progress Report 

108
Fuels Technologies FY 2005 Progress Report 

V Petroleum Displacement Fuels/

Fuel Blending Components

109 
Fuels Technologies FY 2005 Progress Report 

110
Fuels Technologies FY 2005 Progress Report 

V.1 Operability Results of Class 6 Vehicles Operating on GTL Fuel with 

Catalyzed DPFs 

Teresa L. Alleman (Primary Contact), Robert L. McCormick 

National Renewable Energy Laboratory 

1617 Cole Blvd, MS 1633 

Golden, CO 80401 

DOE Team Lead: Steve Goguen 

DOE Technology Development Manager: Kevin Stork 

Project Partners: 

South Coast Air Quality Management District, Diamond Bar, CA 

International Truck and Engine Corporation, Melrose Park, IL 

Johnson Matthey, Inc., Malvern, PA 

Shell Global Solutions (U.S.) Inc., Houston, TX 

Yosemite Waters, Fullerton, CA 

Objectives 

• Assess real-world impact of gas-to-liquid (GTL) diesel fuel combined with catalyzed diesel particle filters 

(DPFs) on emissions, operability, and operating costs in a heavy-duty truck fleet, including fuel economy 

and maintenance costs. 

Accomplishments 

• Completed six-month operability analysis from fleet fueling and maintenance records. 

• Demonstrated that a heavy-duty fleet vehicle using GTL fuel with a DPF has similar maintenance costs 

to such a vehicle using conventional fuels. 

Future Directions 

• Use successes from this project as basis for future projects evaluating larger fleets and new technology 

engines and emission control systems. 

Introduction 

Gas-to-liquid (GTL) fuel is a near-zero-sulfur 

and high-cetane diesel fuel that can be substituted for 

conventional diesel fuel. GTL fuel is an attractive 

alternative diesel fuel due to these premium fuel 

properties and the fact that the fuel can be produced 

from renewable and/or domestic resources like coal, 

biomass and natural gas. 

Several studies have shown the emission 

reduction potential of GTL fuel in light- and 

heavy-duty engines and vehicles [1]. Emission 

control systems, which have been tested with GTL 

fuels, are expected to play an integral role in meeting 

upcoming emission regulations. 

While the emission reductions for this fuel have 

already been proven, the impact on fleet operating 

costs has yet to be quantified. By collecting fleet 

fueling and maintenance records, the impact of the 

fuel on operations can be quantified. 

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Fuels Technologies

Approach 

A fleet of six vehicles was selected to participate 

in the project. The vehicles operated on a variety of 

city, suburban, and freeway routes delivering 

5-gallon water bottles to residential and commercial 

customers. The vehicles were nominally identical 

and powered by 2001 model year International 

DT466 engines (195 hp and 525 ft-lb peak torque). 

Half of the vehicles were operated as-is on California 

Air Resources Board (CARB) specification diesel 

fuel with no emission control devices; half the 

vehicles were fueled exclusively with GTL fuel and 

retrofit with Johnson Matthey Catalyzed 

Continuously Regenerating Technology (CCRTTM) 

DPFs. The fleet was operated from January to July, 

2004. 

Fleet maintenance and fueling records were 

collected and analyzed to determine maintenance 

costs for the fuel/filter technologies. Comparison 

and analysis of the records was used to determine if 

any fuel or filter related maintenance was 

experienced by the fleet. Additionally, the real-world 

fuel economy was determined through the fueling 

records. Emissions have been previously reported 

[2]. 

Results 

Fueling records detailing the amount of each fill 

and miles traveled between fills were collected for 

analysis. The records were scrutinized for accuracy, 

and erroneous entries were purged from the data set. 

A confounding factor for the fuel economy for this 

fleet was the dedicated duty cycles for the vehicles. 

Each vehicle operated over a dedicated route with 

varying amounts of freeway and city driving, which 

influenced the fuel economy. On average, the fuel 

economy from the GTL-fueled vehicles was similar 

to that of the CARB diesel-fueled vehicles over the 

study period (Figure 1). Driver feedback on the 

GTL-fueled vehicles was overwhelmingly positive; 

the drivers noted similar performance characteristics 

with the GTL fuel and DPFs. 

The fleet maintenance records were also 

evaluated, including preventative maintenance, 

 FY 2005 Progress Report 

Figure 1. Fuel Economy for the Test Vehicles over the 

6-Month Study Period 

unscheduled maintenance, and warranty events. The 

most significant event during the study period was 

the replacement of the starter in one of the vehicles. 

The starter for this vehicle was replaced twice during 

the study period. The cause of the failure was not 

related to the fuel or filter technology; therefore, 

costs associated with this repair were omitted from 

the data analysis. Beyond this event, four warranty 

items occurred which were remedied at no cost to the 

fleet. The results from the analysis indicated that the 

cost to maintain the CARB-fueled vehicles was 

$0.03/mile and the cost to maintain the GTL fueled 

vehicles was $0.02/mile. Start-up costs, such as filter 

procurement, and fuel costs were not considered in 

this analysis. Given the size of the vehicle fleet 

tested and the precision of fleet maintenance data, the 

costs to operate the CARB-fueled and GTL-fueled 

vehicles are similar. 

Conclusions 

A fleet of vehicles participated in a fleet test to 

determine the operating cost of GTL fuel with a DPF. 

These vehicles were compared to current in-use 

technology vehicles operating on CARB 

specification diesel fuel with no emission control 

systems. The fleet was evaluated for a period of six 

months, with chassis emissions data collection 

(previously reported). The results from the 

operability analysis indicate that the maintenance 

costs and fuel economy were similar for both groups 

112 
Fuels Technologies FY 2005 Progress Report 

of vehicles. Thus, the analysis indicates that 

exclusive of fuel costs, the cost of operating these 

vehicles with GTL fuel and DPFs is similar to the 

cost with conventional fuels and technology. The 

emissions and operability impact of GTL fuel on 

current technology vehicles has been proven. Future 

research should verify similar results for vehicles 

with advanced technology meeting future emissions 

standards. 

FY 2005 Publications/Presentations 

1. “Performance of GTL Fuels: Fuel-Engine 

Compatibility and Achieving Low Emissions”, 

presented to Fuels Technologies Merit Review, 

Denver, CO, March 2005. 

2. “Comparison of Two Rounds of Chassis Emission 

Testing from a Fleet of Class 6 Trucks with GTL Fuel 

and Catalyzed DPFs”, poster presentation at 15th 

CRC On-Road Emissions Workshop, San Diego, CA, 

April 2005. 

3. Alleman, T.L., Barnitt, R., Eudy, L., Miyasato, M., 

Oshinuga, A., Corcoran, T., Chatterjee, S., Jacobs, T., 

Cherrillo, R.A., Clark, N., Wayne, W.S., “Final 

Operability and Chassis Emissions Results from a 

Fleet of Class 6 Trucks Operating on Gas-to-Liquid 

Fuel and Catalyzed Diesel Particle Filters”, SAE 

Technical Paper No. 2005-01-3769, 2005. 

References 

1. Alleman, T.L., McCormick, R.L., “Fischer-Tropsch 

Diesel Fuel – Properties and Exhaust Emissions: 

A Literature Review”, SAE Technical Paper No. 

2003-01-0763, 2003. 

2. Alleman, T.L., Eudy, L., Miyasato, M., Oshinuga, A., 

Allison, S., Corcoran, T., Chatterjee, S., Jacobs, T., 

Cherrillo, R.A., Virrels, I., Nine, R., Wayne, S., 

Lansing, R., “Fuel Property, Emission Test, and 

Operability Results from a Fleet of Class 6 Vehicles 

Operating on Gas-to-Liquid Fuel and Catalyzed 

Diesel Particle Filters”, SAE Technical Paper No. 

2004-01-2959, 2004. 

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Fuels Technologies FY 2005 Progress Report 

V.2 Biodiesel Quality and Stability 

Robert L. McCormick (Primary Contact), Teresa Alleman 

National Renewable Energy Laboratory (NREL) 

1617 Cole Boulevard, MS1633 

Golden, Colorado 80401 

DOE Technology Development Manager: Dennis Smith 

Subcontractors: 

Magellan Midstream Partners, Kansas City, Kansas 

Southwest Research Institute, San Antonio, Texas 

Objectives 

• Insure that biodiesel is of adequate quality and stability. 

Approach 

• Conduct a nationwide survey of biodiesel blend (B20) quality and stability. 

Accomplishments 

• Completed nationwide assessment of biodiesel (B20) quality and stability. 

• Identified a significant issue with blending of biodiesel to form homogeneous mixtures. 

• Identified potential issues with peroxide formation and low water interfacial tension that require further 

investigation. 

Future Directions 

• Complete nationwide survey of B100 and B20 quality and stability, applying lessons learned from 2004 

and 2005 surveys. 

• Complete a detailed study of oxidation stability of B100, B20, and B5 with the objective of determining 

the best test method and specification limits. 

Introduction 

Biodiesel consists of fatty acid methyl esters 

produced from vegetable oils, animal fats, and waste 

cooking oil via transesterification with methanol. 

The primary feedstocks for biodiesel in the United 

States are soybean oil and waste cooking oil (yellow 

grease). Approximately 94 million liters (25 million 

gallons) of biodiesel were consumed in the United 

States during 2001 [1], with estimates of current 

consumption in the range of 75 million gallons 

annually. The current annual production potential 

for biodiesel based on feedstock supplies is estimated 

at 5.8 billion liters (1.5 billion gallons) [2] from an 

analysis assuming high petroleum fuel prices that 

create strong demand for a renewable replacement. 

Life cycle analysis indicates that biodiesel is truly 

renewable and its use, therefore, produces real 

reductions in petroleum consumption and carbon 

dioxide emissions [3]. Thus, biodiesel holds the 

potential to displace on the order of 5% of on-road 

diesel fuel, consistent with the Office of 

FreedomCAR and Vehicle Technology (OFCVT) 

program goals for fuels R&D. 

To insure adequate fuel quality, biodiesel (B100) 

intended for blending in the United States must meet 

the requirements of American Society for Testing 

and Materials (ASTM) Standard D6751. However, 

at present there is no quality specification for 20% 

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Fuels Technologies

biodiesel blends (B20), the current most common 

blend level. This study examined the quality of B20 

samples collected nationwide in order to provide data 

relevant to development of a new ASTM 

specification. 

Approach 

Fifty sites using B20 from across the country 

were selected to participate in the B20 quality 

survey. The basis of selection was two-fold: to 

represent the range of weather-related operating 

environments across the U.S. and to represent all of 

the U.S. major (greater than one million gallon 

annual production) biodiesel producers. However, 

samples were collected in August and September of 

2004, so the survey does not reveal properties 

relevant to wintertime operation. 

The test plan consisted of tests or properties to be 

measured for the B20 samples, as shown in Table 1. 

Magellan Midstream Partners performed all tests 

except oxidation stability by Rancimat. Robert 

Table 1. Tests conducted for B20 samples 

Property Test Method 

Water and Sediment

a ASTM D2709 

Visual Appearance ASTM D4176 Procedure 2 

Acid Number WLS-102 

(Field Acid Number) 

Kinematic Viscosity ASTM D445 

Silver Strip Test IP227 

Peroxide Number ASTM D3703 

Oxidation Stability EN14112 (Rancimat) 

Water Extraction GM Test Method 

Density ASTM D4062 

Carbon Residue ASTM D524 

Biodiesel Content FTIR Method 

Cloud Point ASTM D2500 

Distillation (T90) ASTM D86 

Sulfur Content ASTM D5453 or D2622, 

as appropriate 

 FY 2005 Progress Report 

Bosch Corporation and Southwest Research Institute 

supplied replicate Rancimat data sets. In addition, 

Parker-Racor supplied interfacial tension 

measurements. The National Biodiesel Board’s B20 

Fleet Evaluation Team, a committee of primarily 

automotive industry technical experts, proposed this 

list of tests. 

Results 

Results for the following tests showed no reason 

for concern (i.e., they met D975 requirements for 

No. 2 diesel or were otherwise within normal range): 

Water and Sediment, Visual Appearance, Kinematic 

Viscosity, Silver Strip Corrosion, Density, Acid 

Number, Cloud Point, and Carbon Residue. The 

results for the balance of the tests conducted are 

discussed in more detail below, with full results 

available at NREL’s website [4]. 

Biodiesel Content 

Figure 1 shows results of biodiesel content 

determination for the 50 B20 quality survey samples. 

Thirty-two of the samples were nominally B20 

(between 18 and 22 percent biodiesel), while the 

remaining 18 samples exhibited biodiesel content 

from 7% to 98%. We believe that this indicates a 

serious issue with biodiesel blending practices. 

Figure 1. Percent Biodiesel Content for B20 Quality 

Survey Samples aTest to be conducted only if D4176 haze rating is significant 

115 
Fuels Technologies FY 2005 Progress Report 

However, it should be noted that no specific protocol Peroxide Value 

was followed for the collection of these samples. 

Most blenders prepare blends by so-called splash 

blending, where the blends are prepared by pumping 

biodiesel and petroleum diesel sequentially into a 

tank (typically a transport truck or storage tank). 

Apparently, in many cases, a homogeneous mixture 

of biodiesel and petroleum diesel is not being 

obtained. Because B100 is slightly more dense than 

petroleum diesel, a poorly blended tank will have a 

high biodiesel content on the bottom of the tank and 

a low biodiesel content at the top of the tank. 

While the use of blends containing less than 

20% biodiesel is not a concern from a maintenance 

and durability standpoint, the use of blends with 

dramatically high biodiesel content can cause serious 

issues. The National Biodiesel Board is currently 

working with biodiesel producers and blenders to 

make sure that proper blending procedures are 

followed. These primarily involve insuring that 

adequate splashing or turbulence is occurring during 

blending. As the industry grows, a transition from 

splash blending to in-line blending should occur and 

will eliminate this problem. 

Distillation 

Figure 2 shows 90% recovery distillation 

temperatures (T90) for the survey samples. Many of 

the B20 samples meet the 338°C (640°F) upper limit 

for No. 2 diesel fuel, but a significant fraction do not. 

This suggests that any future B20 quality 

specification will require a slightly higher T90 limit 

than is currently used for No. 2 diesel. 

Figure 3 shows results of peroxide value 

measurements for the quality survey samples. 

Peroxides can form as a result of biodiesel or 

petroleum diesel oxidation, and ultimately can 

decompose yielding aldehydes, acids, and polymers. 

They are of concern because of the potential to form 

acids and deposits, and also because certain fuel 

system plastics and elastomers may degrade in the 

presence of certain types of peroxides. The results 

show a broad range of peroxide content from values 

less than 10 which are not of concern to values of 

several hundred. 

While these high peroxide values may raise 

significant issues, there are a number of unanswered 

questions that must be answered in order to 

understand their significance. First, we do not know 

the peroxide content of a typical diesel fuel, nor do 

we know the tolerance of diesel fuel system 

elastomers/plastics to diesel fuel derived peroxides. 

Second, this method for measuring peroxides was not 

developed specifically for biodiesel or biodiesel 

blends but for testing of gasoline and jet fuel. Thus, 

it is possible that the reported high peroxide values 

are an experimental artifact of applying this method 

to a substance for which it was not intended and that 

peroxide levels are not, in fact, this high. Research to 

answer these questions is currently ongoing. 

Additionally, in the near future, the B100 quality 

specification will be modified to include an oxidation 

stability requirement. This will presumably prevent 

or limit the potential for peroxide formation. 

Figure 2. Distillation Results (ASTM D86) for B20 

Quality Survey Samples (horizontal dashed line 

shows upper T90 limit for No. 2 diesel fuel) 

Figure 3. Peroxide Value (or number) Determined by 

ASTM D3703 for Quality Survey Samples 

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Fuels Technologies

Interfacial Tension 

Parker-Racor kindly supplied the results for 

interfacial tension. These tests were conducted using 

ASTM D971 Interfacial Tension of Oil Against 

Water by the Ring Method. Results of water 

interfacial tension (IFT) measurements are shown in 

Figure 4. Having an adequately high interfacial 

tension is required for on-board vehicle water 

separators that operate based on coalescence. A 

coalescer that operates in the upper 95% efficiency 

range in high interfacial tension fuel (around 30 

dynes/cm) may show a decrease in efficiency by up 

to 30% as the IFT decreases below 25 dynes/cm 

depending on the type of medium being used in the 

coalescer (per SAE J1488). So, coalescence as a 

mechanism for water separators (which most water 

separators depend on) is highly influenced by fuel 

chemistry (i.e., IFT). 

Of the 33 samples analyzed, only six displayed 

interfacial tensions above 15 dynes/cm. There were 

13 samples that had IFTs at or below 10 dynes/cm. 

Of the six samples that had IFTs over 15 dynes/cm, 

the highest was only 19.5 dynes/cm. Water 

separation from diesel fuel begins to become 

unpredictable below 25 dynes/cm. In areas where 

there is not much water in fuel, it would probably not 

be noticed. In areas where there is often water in 

diesel fuel, this could lead to higher injector 

maintenance costs, over long periods of time, than 

previously experienced using diesel fuels with higher 

interfacial tension. 

 FY 2005 Progress Report 

Thus, these results are a serious concern, but 

there are a number of outstanding questions. It is 

possible that the low IFT is caused by highly polar 

compounds in the biodiesel blends such as the 

peroxides noted above. Implementation of an 

oxidation stability requirement would be expected to 

mitigate the problem of low IFT as well. Also, it is 

possible that other types of coalescer media and other 

types of water removal devices could be 

implemented. This might include the installation of 

specifically designed water separation filters/devices 

at the fuel dispenser nozzle for separation of water 

prior to pumping into the vehicle fuel tank. 

Oxidation Stability by Rancimat 

Southwest Research Institute performed the 

Rancimat test and provided 20 replicate results for a 

peanut oil standard showing a mean of 5.04 hr, 

standard deviation of 0.22 hr, and 95% confidence 

interval of +/-0.1 hr. A striking feature of these 

results is evident from the frequency plot of Figure 5. 

Twenty-one out of the thirty-six samples tested 

exhibited induction times of less than 2.5 hr. Much 

longer induction times were anticipated based on the 

very long times typically reported for petroleum 

derived diesel fuel, which makes up a large fraction 

of the composition of these samples. The short 

induction times may have been observed because of 

the age of these samples when tested. The samples 

were collected in September and October of 2004 

and most analyses were conducted soon after. 

However, the Rancimat measurements were made in 

March and April of 2005, roughly 6 months later. 

Figure 4. Results of Water Interfacial Tension 

Measurements by ASTM D971 for B20 Survey 

Samples 

Figure 5. Frequency Distribution for B20 Rancimat 

Stability Test Results 

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Fuels Technologies

Although these small samples were stored in an 

air-conditioned laboratory environment in sealed 

containers, the “oxidation reserve” of these samples 

may have been depleted during this time. It is 

recommended that in future quality surveys all tests 

be conducted within one month of sample collection. 

Conclusions 

Because no fuel quality specification currently 

exists for B20, we cannot compare the results of this 

survey to standard requirements. Most of the 

properties examined showed acceptable levels for 

use in diesel engines. However, the survey data point 

to a number of issues and potential issues. Chief 

among these is the biodiesel content of the 

supposedly B20 samples. Only 32 out of the 50 

samples contained nominally 20% biodiesel. The 

cause of this is believed to be inadequate mixing 

during splash blending of these fuels. This result is 

being made widely known to the biodiesel industry in 

hopes that education on proper blending procedures 

can solve this problem. 

Additionally, many of the B20 samples exhibited 

high levels of peroxides. This is of concern because 

certain vehicle fuel system components are made of 

materials that may not be compatible with peroxides. 

However, this contention is based on experience with 

gasoline, and the peroxides that form in biodiesel are 

chemically much different, having a much higher 

molecular weight. It is not known if biodiesel 

peroxides will produce the same effects on fuel 

system materials. Furthermore, it is widely agreed 

that the B100 specification, and perhaps the B20 

specification, should include an oxidation stability 

requirement. Should such a requirement be 

implemented, it seems highly likely that antioxidant 

additives would be used to meet it, resulting in much 

lower potential for peroxide formation. 

The B20 samples exhibited low interfacial 

tension with water when tested using the ring 

method. A minimum level of interfacial tension is 

required for the proper performance of water 

separators that are used in engine fuel systems to 

protect the engine from water in the fuel. There are a 

number of potential causes of this problem, including 

the presence of highly polar materials such as 

peroxides in the biodiesel. Thus, this is another issue 

that might be resolved by implementation of an 

oxidation stability requirement. 

 FY 2005 Progress Report 

The B20 samples were tested for oxidation 

stability by the Rancimat method. Many of the 

samples exhibited induction times of less than 

2 hours; however, the samples had been stored for 

on the order of 6 months prior to the oxidation 

stability measurements. Thus, it is not clear if the 

short induction times are intrinsic properties of these 

samples or are caused by the relatively long storage 

time where the samples’ capacity to resist oxidation 

was consumed. 

Future surveys of B20 quality should insure that 

all tests are conducted within one month of sample 

collection. Additionally, future surveys should 

include other oxidation stability tests such as ASTM 

D2274. 

FY 2005 Publications/Presentations 

1. McCormick, R.L., Alleman, T.L., Moens, L., 

Ratcliff, M., Lawrence, R. “Survey of the Quality and 

Stability of Biodiesel and Biodiesel Blends in the 

United States in 2004,” National Renewable Energy 

Laboratory, NREL/TP-540-38836, October 2005 

http://www.nrel.gov/docs/fy06osti/38836.pdf. 

References 

1. United States Department of Energy, Energy 

Information Agency, Alternatives to Traditional 

Transportation Fuels 2000, http://www.eia.doe.gov/ 

cneaf/alternate/page/datatables/ table10.html, 

accessed October 25, 2004. 

2. Tyson, K.S., Bozell, J., Wallace, R., Petersen, E., 

Moens, L. “Biomass Oil Analysis: Research Needs 

and Recommendations,” National Renewable Energy 

Laboratory, NREL/TP-510-34796, June 2004. 

3. Sheehan, J., Camobreco, V., Duffield, J., 

Graboski, M. Shapouri, H. “An Overview of 

Biodiesel and Petroleum Diesel Life Cycles,” 

National Renewable Energy Laboratory, 

NREL/TP-580-24772, May 1998. 

4. McCormick, R.L., Alleman, T.L., Moens, L., 

Ratcliff, M., Lawrence, R. “Survey of the Quality 

and Stability of Biodiesel and Biodiesel Blends in the 

United States in 2004,” National Renewable Energy 

Laboratory, NREL/TP-540-38836, October 2005 

http://www.nrel.gov/docs/fy06osti/38836.pdf. 

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Fuels Technologies FY 2005 Progress Report 

V.3 Resolving Barriers and Showing Incentives for Non-Petroleum Fuels in 

Near-Term Uses – Oil Sands Fuels Characterization 

Samuel A. Lewis, Sr., John M. E. Storey (Primary Contact), Bruce Bunting, Michael Kass 

Oak Ridge National Laboratory at NTRC 

P.O. Box 2008, MS 6472 

Oak Ridge, TN 37831-6472 

DOE Technology Development Manager: Kevin Stork 

Objectives 

• Research and experiments will be conducted to clear any barriers to use of non-petroleum based fuels 

(NPBF) in the near-term 

• Develop or implement analytical methods for identifying unique components of NPBFs, including fuels 

from the Athabascan Oil Sands 

Approach 

• Establish relationships with Canadian counterparts for research on fuel properties 

• Develop separation methods for cycloparaffinic compounds 

• Develop identification methods for cycloparaffins and other unique compounds 

• Determine fuel chemistry and property effects on engine performance, including combustion, lubricity, 

and emissions controls performance 

Accomplishments 

• Utilized blended oil sands fuel for operation of a light-duty diesel equipped with a NOx adsorber catalyst 

using in-cylinder regeneration modes 

• Separated oil sands fuel fractions with large column chromatography 

– Urea crystallization used to remove alkanes 

• Developed a combination of electron impact (EI) and chemical ionization (CI) mass spectroscopic (MS) 

methods for identification of fuel components 

• Utilized oil sands blend in advanced engine and emissions systems 

Future Directions 

• Extend chemical analysis to several upgrader streams of oil sands fuels 

– Relate to parallel characterization at other national laboratories 

• Research engine performance with the same fuel streams in normal and advanced combustion modes 

to understand potential fuel chemistry effects 

• Identify other near-term NPBFs such as shale-derived fuels for analysis 

• Report in the literature on findings 

Introduction However, if substitution is hurried and problems 

arise with engines or vehicles, the substitution 

As a key ingredient of national energy security, process can be set back. Some properties of NPBFs 

DOE wishes to utilize NPBFs to the extent possible. may actually be found that provide incentive for their 

119 
Fuels Technologies

use. An emissions benefit from an NPBF additive 

would be an example. However, regulated and 

unregulated emissions from NPBFs must be 

evaluated to ensure that no new toxic emissions are 

produced. Reliable, thorough data regarding the 

benefits and issues of NPBFs need to be developed 

before these fuels will be adopted. 

As an example of a NPBF, the synthetic crudes 

derived from Athabascan heavy crude are already 

making an impact on the Nation’s energy supply. 

Canada is the largest supplier of crude oil to the U.S. 

and their present production of Athabascan heavy 

crude represents around 40% of their total crude oil 

production. Canada exports between 80 and 90% of 

their crude oil production to the U.S. and it is likely 

that oil sands liquids will represent an increasing 

portion of our transportation fuel.. 

The composition of Athabascan heavy crude 

differs from other crude oil sources, most notably in 

the large percentage of unsaturated hydrocarbon and 

aromatic species present in the heavy crude. This 

requires the crude to be hydro-treated before 

shipment to U.S. refineries. This treatment results in 

a higher-than-normal concentration of cycloparaffins 

among other products. The high percentage of 

cycloparaffins affects downstream refining 

procedures and fuel quality, generally increasing 

energy requirements for fuel production. If, instead, 

combustion parameters can be modified to exploit 

the cycloparaffins, then less refining energy would be 

required. A thorough chemical understanding of 

fuels derived from heavy crude can help guide 

optimization of combustion in future engine designs. 

Basic chemical composition of diesel fuel can be 

classified into four groups: paraffins, isoparaffins, 

cycloparaffins and aromatics. The determination of 

the types and quantity of cycloparaffin 

configurations in this diesel fuel is an important 

variable and should be considered when 

characterizing this fuel. 

Approach 

We propose the following protocol for the 

quantification and identification of cycloparaffins. 

Separation of Cycloparaffins: Because 

cycloparaffins have the same molecular weight and 

similar boiling points as straight-chain alkanes and 

 FY 2005 Progress Report 

alkenes, it can be challenging to separate and identify 

these compounds in a complex mixture such as diesel 

fuel. Using ASTM Method 2549-91, diesel fuel is 

separated into two groups: paraffins and aromatics. 

The paraffin mixture can be further separated into 

n-paraffins, isoparaffins and cycloparaffin groups. 

The differences in solubility of cycloparaffins and 

paraffins in solutions of urea and thiourea can be 

exploited to separate the compound classes [1]. The 

crystallization of urea from solution selectively 

removes paraffins. The remaining solution of 

isoparaffins and cycloparaffins can be further 

separated using thiourea. 

Identification of cycloparaffins: Cycloparaffins 

can be identified by mass spectroscopy (MS) or 

nuclear magnetic resonance (NMR) spectroscopy. 

MS is the most promising method due to the flexible 

ionization techniques and small sample volumes 

required. Using a soft ionization technique such as 

chemical ionization, the molecular weights of these 

cycloparaffins may be determined. A higher-energy 

ionization technique, such as electron ionization, 

would result in fragmentation patterns that provide 

insight into the molecular structure. MS analysis 

would also relax separation requirements due to the 

uniqueness of mass spectrum or molecular weight for 

different groups of these compounds. Due to 

differences in ionization efficiency, quantification 

using standards of the compounds of interest must be 

done. 

With NMR, the determination of the chemical 

structure could be accomplished by proton or 13C 

probes, and the quantity could be calculated by 

integrating the area of the signal. Problems with the 

NMR technique may lie in the typical concentrations 

needed for detection. Typically, a concentration in 

the high parts per million is required. An additional 

drawback is associated with the difficulty in 

interpreting mixtures possessing the same basic 

structure, although the newest, high-resolution 

NMRs may overcome this challenge. 

As part of the determination of near-term 

suitability of NPBFs, Oak Ridge National Laboratory 

(ORNL) will evaluate the performance of NPBFs in 

advanced engine systems, including homogeneous 

charge compression ignition (HCCI) engines, and 

advanced diesel aftertreatment systems. Engine 

experiments with full-size catalysts will feature 

120 
Fuels Technologies

hydrocarbon (HC) speciation to characterize 

different regeneration and desulfation strategies and 

their effects on the NOx adsorber performance. 

Results 

Thus far, the urea crystallization separation and 

analyses with gas chromatography (GC)/MS have 

been completed for a blended oil sands fuel. Figure 1 

illustrates the total ion chromatograms for the oil 

sands fuel and ECD1, a low-sulfur test fuel produced 

by BP Amoco between 2001 and 2003. Note that the 

envelope and boiling range look very similar for 

these fuels. The difference between the fuels is that 

the oil sands fuel has cycloparaffins whereas the 

ECD1 has mainly branched alkanes in addition to the 

n-alkanes. In Figure 2, the same fuels are compared 

after urea encapsulation, which removes the 

n-alkanes. Note that the envelope of the ECD is 

much smaller due to its paraffinnic content being 

removed, where as the extended envelope of the oil 

sands fuel indicates a broader base of compounds. 

Figure 1. Gas chromatograms of (a) ECD1, a low-sulfur 

refinery fuel from petroleum sources, and 

(b) an oil sands blend provided to ORNL by 

Natural Resources Canada. TIC is total ion 

counts, indicating the combined signal of all 

of the ions measured by the mass spectrometer. 

 FY 2005 Progress Report 

These chromatograms were obtained with the MS in 

electron impact (EI) ionization mode. 

Because the cycloparaffins can have the same 

base molecular mass as olefins, it was necessary to 

distinguish between them. Chemical separation can 

be effected with thiourea crystallization, but it was 

desirable to use an analytical technique that directly 

distinguished without further preparatory steps. By 

using a mass spectrometer in positive chemical 

ionization (CI) mode with CH4, the two classes of 

compounds produced different molecular ions. CI of 

cycloparaffins produces a strong (M-1)+ peak, that is, 

a molecular ion with a mass 1 less than the molecular 

weight of the compound. CI of olefins produces a 

strong (M+1)+ peak, a molecular ion with a mass 1 

greater than its molecular weight [2]. Figure 3 

illustrates the importance of the distinction. Note 

that the EI spectra of the two adjacent peaks, 

representing two distinct compounds, have the same 

molecular ion of 166. The fragmentation patterns are 

different, but the first peak could still represent a 

branched olefin, for instance. The CI spectra show 

the differences, with the first peak having a (M-1)+ 

ion of 165, and the second peak having a (M+1)

+ ion 

of 167 present. The first peak is a cycloparaffin, 

dimethyl decalin, while the second peak is an olefin 

with two double bonds. Figure 4 shows the different 

molecular structures of decalins found in the oil 

sands blend. 

The differences in molecular structure 

notwithstanding, the oil sands blend has similar fuel 

properties to many of the hydrogen-rich fuels 

Figure 2. A comparison of ECD1 and the oil sands fuel 

after treatment by urea encapsulation to remove 

n-alkanes. 

121 
Fuels Technologies FY 2005 Progress Report 

Figure 3. A comparison of EI and CI spectra of two compounds in the oil sands fuel. 

The compounds are of the same molecular weight. 

expected to meet the 2006 standard for S content. 

At ORNL, this fuel was used in a single-cylinder 

research engine as part of a study of cetane effects on 

Figure 4. Substituted Decalins Found in the Oil Sands 

Fuel 

HCCI combustion. The performance of the fuel in 

this engine was consistent with traditional petroleumbased fuels of similar cetane number. 

The oil sands fuel was also used in a 1.7L fourcylinder diesel engine operating in high-efficiency 

clean combustion (HECC) modes. It behaved 

similarly to the BP15 test fuel, which has similar 

distillation properties, cetane and sulfur level under 

these combustion conditions. In a third ORNL study, 

the oil sands blend was incorporated into a fuels 

study of NOx adsorber regeneration. During the 

“rich” regeneration period of a NOx adsorber system, 

ORNL has shown that different fuel chemistries 

generate different exhaust species [3], and the 

question was whether or not these differences 

affected NOx reduction performance. Under the 

particular engine conditions studied, the oil sands 

fuel was found to perform very similarly to BP15 for 

two different rich-lean regeneration intervals. Figure 

5 illustrates the comparison for short and long 

regeneration intervals at the same steady-state 

operating point. 

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Fuels Technologies

Figure 5. A comparison of NOx conversion performance 

for a light-duty engine equipped with a NOx 

adsorber system for two different ultra-low 

sulfur fuels. 

Conclusions and Future Effort 

The fuels analysis work demonstrated a 

reasonable method for determining the 

cycloparafinnic compounds in fuels derived from the 

Athabascan Oil Sands. Several derivatives of 

decalin, the base 10-carbon cycloparaffin, were 

identified. Additional methods using multidimensional chromatography as well as 

derivatization for liquid chromatographic separations 

will be investigated. 

 FY 2005 Progress Report 

In terms of near-term usage in advanced engine 

systems, the oil sands blends tested performed in 

close accordance with bulk fuel properties such as 

cetane and distillation range in a single-cylinder 

HCCI engine, during HECC modes in a four-cylinder 

engine, and during NOx regeneration studies. Our 

continuing combustion projects plan to include oil 

sands and other NPBFs in the matrix.FY 2005 

Publications/Presentations 

FY 2005 Publications/Presentations 

1. Sluder, C.S., Wagner, R.M., Lewis, S.A., and 

Storey, J.M.E. “Fuel Property Effects on Emissions 

from High Efficiency Clean Combustion in a Diesel 

Engine,” accepted for SAE Congress 2006. Society 

of Automotive Engineers. 

References 

1. Lappas, A.A.; Patiaka, D.; Ikonomou, D.; 

Vasalos, I.A. “Separation and characterization of 

paraffins and naphthenes from FCC feedstocks.” 

Industrial & Engineering Chemistry Research, 

36, 8 (1997) 

2. Field, F.H. Journal of The American Chemical 

Society, 90, 5649 (1968) 

3. West, B.H., Huff, S. P., Parks, J.E., Lewis, S.A., 

Choi, J-S., Partridge, W.P., and Storey, J.M.E. 

“Assessing reductant chemistry during in-cylinder 

regeneration of diesel lean NOx traps.” SAE Paper 

no. 2004-01-3023, Society of Automotive Engineers 

(2004). 

123 
Fuels Technologies FY 2005 Progress Report 

124
Fuels Technologies FY 2005 Progress Report 

VI New Technology Impacts

125
Fuels Technologies FY 2005 Progress Report 

126
Fuels Technologies FY 2005 Progress Report 

VI.1 Weekend Ozone Effect Studies 

Douglas R. Lawson 

National Renewable Energy Laboratory 

1617 Cole Blvd., MS 1633 

Golden, CO 80401 

DOE Technology Development Manager: James J. Eberhardt 

Subcontractor: 

Envair, Berkeley, CA 

Objectives 

• Ambient ozone (O3) levels in southern California are about 50% higher on Sundays than on mid-week 

days. The objective of this study is to identify whether this phenomenon exists in other parts of the U.S. 

that experience violations of the national ambient air quality standard for ozone. 

• This project will characterize day-of-week differences in: 

– ambient concentrations of primary pollutants, including nitric oxide (NO), oxides of nitrogen (NOx), 

speciated volatile organic compounds (VOCs), carbon monoxide (CO), and black carbon (BC); 

– ambient concentrations of ozone and particulate matter (PM) nitrate; 

– responses of ozone and PM nitrate concentrations to changes in the ambient concentrations of primary 

pollutants. 

The principal focus is on the gas-phase species NO, NOx, CO, VOCs, ozone, and PM nitrate. 

Approach 

The analyses were carried out at ambient air quality monitoring sites in ozone problem areas in 23 states: 

the Northeast corridor (including the New York-Northern New Jersey-Long Island, Philadelphia-WilmingtonTrenton, and Baltimore-Washington metropolitan areas); the Gulf of Mexico coast (including the HoustonGalveston-Brazoria and Beaumont-Port Arthur and Baton Rouge metropolitan areas); Dallas-Fort Worth; 

Phoenix; and the Colorado Front Range area (including Denver, Colorado Springs, Boulder, and Fort Collins). 

Previous work carried out for the Atlanta area and for six Midwestern states (Ohio, Michigan, Indiana, Illinois, 

Missouri, and Wisconsin) was also incorporated in this study. The time period analyzed was 1998 through 

2002 (or 2003 where data were available). 

Accomplishments 

• Completed analysis of 1998-2002 or 2003 ambient ozone precursor and ozone data from many U.S. 

monitoring locations. 

• Wrote and sent draft report to air quality staff in the regions/states studied for technical comments and peer 

review. The report was sent to the states of Arizona, Texas, and Colorado; Northeast States for 

Coordinated Air Use Management; Mid-Atlantic Regional Air Management Association; and the Lake 

Michigan Air Directors Consortium. 

• Submitted paper summarizing study results to the Journal of the Air & Waste Management Association for 

peer review and subsequent publication. 

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Fuels Technologies FY 2005 Progress Report 

Future Directions 

• Began proximate ozone modeling study in southeast Michigan region in November 2005, in collaboration 

with state and local government groups and industry representatives in that area. 

Introduction 

The occurrence of generally comparable – or 

even higher – ambient concentrations of ozone on 

Saturdays and Sundays than on other days of the 

week is commonly known as the “weekend effect for 

ozone,” or, simply, the “weekend effect.” Because 

emissions of ozone precursors, including volatile 

organic compounds (VOC), oxides of nitrogen 

(NOx), and carbon monoxide (CO), are lower on 

weekends than on weekdays, the weekend ozone 

effect is counterintuitive. To provide a better 

understanding of the implications of the weekend 

effect, a thorough analysis of weekday and weekend 

precursor concentrations and composition is needed. 

Observed in air quality data from the mid-1960s and 

early 1970s, the weekend effect in California 

recently has been studied at length. Fujita et al. [1] 

and Lawson [2] conclude that weekend reductions of 

NO emissions are the most important factor leading 

to higher weekend ozone, allowing ozone to 

accumulate earlier in the day and to reach higher 

concentrations compared with weekdays, and that 

proposed alternative hypotheses are not supported by 

ambient data and do not explain the weekend effect 

in southern California. In contrast, Croes et al. [3] 

considered the available air quality data and 

photochemical models inadequate to conclusively 

determine the causes of the weekend ozone effect in 

southern California. 

This study provides further analysis of the 

weekend ozone effect in areas of the United States 

outside California. The weekend ozone effect 

provides air quality managers and scientists the 

opportunity to make empirical observations of the 

kind that are so important in testing hypotheses by 

asking “What if” questions regarding emission 

reductions that are needed to reduce ambient O3 

levels. Seldom are such opportunities available 

using ambient data regarding how the atmosphere 

actually responds to changes in emissions because 

most air quality regulations provide small 

incremental benefits and take effect over long 

periods of time. 

Approach and Results 

Ambient air quality monitoring data were 

analyzed to evaluate the differences between mean 

day-of-week ambient concentrations of ozone 

precursors (NO, NOx, CO, and VOC) using 1998­

2003 ambient air-pollutant data from monitoring 

sites in 23 states in New England, the Midwest, the 

mid-Atlantic, and isolated urban areas in the western 

and southern U.S. During the months of March 

through October, median decreases of NO, NOx, and 

CO at 6 a.m. Sundays compared with 6 a.m. 

Wednesdays were 71, 58, and 42 percent, 

respectively, as shown in Figure 1. The median 

Figure 1. Median ambient pollutant concentration 

decreases from Wednesdays to Sundays. 

Results are shown for morning and noon 

concentrations of NO, NOx, and CO (March – 

October), and for 1-hour and 8-hour peak 

ozone concentrations on all ozone-season days 

(March – October) and on high-ozone days 

(top three peak days per day of week per year). 

PM nitrate levels are obtained from 24-hour 

sampling periods. Positive values represent 

higher Wednesday concentrations; negative 

values indicate that concentrations were higher 

on Sundays than on Wednesdays. The time 

period analyzed was 1998 through 2003. 

128 
Fuels Technologies

declines of NO, NOx, and CO at 12 noon Sundays 

compared with 12 noon Wednesdays were 46, 40, 

and 12 percent, respectively. The Wednesday/ 

Sunday PM nitrate median decline at 69 sites was 

2.6%, with the difference statistically significant at 

only one location. 

The large reductions in ambient concentrations 

of ozone precursors on weekends did not produce 

meaningful reductions of ambient ozone levels. To 

the contrary, median 1-hour and 8-hour ozone daily 

maxima on Sundays increased by 1 and 3 percent, 

respectively, from their mean peak levels on 

Wednesdays. When restricted to high-ozone days, 

the median 8-hour ozone daily maxima were 

unchanged on Sundays compared with Wednesdays, 

while the median 1-hour peak ozone levels decreased 

by 2 percent from Wednesdays to Sundays. 

The changes observed in weekend ozone levels 

relative to weekday concentrations were the net 

result of weekday/weekend differences in a number 

of processes affecting ozone formation, including 

emissions, ozone transport, and local ozone 

formation: 

• Ozone accumulation began about one hour 

earlier on Sundays than on Wednesdays. Ozone 

can accumulate only after NO concentrations fall 

to low levels. 

• Regional ozone levels contributed the majority 

of the peak ozone concentrations measured 

downwind of four urban areas where ozone 

transport was studied in detail (Atlanta, Chicago, 

Dallas-Fort Worth, and Phoenix). 

• Statistically significant day-of-week differences 

in ozone levels did not occur at either upwind or 

downwind locations. Ozone concentrations 

averaged about 5 to 10 ppbv lower on Sundays 

than on Wednesdays upwind of Atlanta, 

Chicago, and Phoenix; none of these differences 

were statistically significant, and no day-of-week 

transport differences were observed for DallasFort Worth. Data from the Houston area are 

depicted in Figure 2. 

Conclusions 

The weekend ozone effect provides a natural 

experiment for understanding how urban ozone and 

 FY 2005 Progress Report 

PM nitrate respond to large reductions in ozone 

precursor emissions. The data suggest that, for ozone 

problem areas in and downwind of urban U.S. 

locations, VOC emission reductions reduce ozone, 

while NOx emission reductions increase ambient 

ozone levels. Despite large weekend reductions of 

NO emissions, there is little change in PM nitrate 

concentrations on weekends. The findings from this 

study may require a rethinking of present control 

strategies to reduce urban ozone and PM nitrate 

exposure and ozone transported downwind of urban 

locations in the U.S. 

We interpret the observed absence of differences 

between weekday and weekend ozone levels, in 

combination with significantly lower ambient levels 

of NOx, as an indication that ozone formation in our 

study areas is VOC-limited. Our analyses of 

weekday/weekend differences in ozone precursor 

emissions show that different emission reductions 

of ozone precursors than normally take place on 

weekends will be required before significant 

reductions in ambient ozone can be achieved. Yet, 

in relative magnitudes, the emission changes that are 

projected to occur between now and 2010 more 

closely resemble the weekend reductions that we 

report here than the historical emissions trends, 

in which VOC emission reductions have exceeded 

reductions of NOx emissions on a relative basis. 

Our results call into question the rates of future 

progress in reducing peak ozone levels in major 

metropolitan areas in the United States. 

References 

1. Fujita, E.M., W.R. Stockwell, D.E. Campbell, 

R.E. Keislar, D.R. Lawson. Evolution of the 

magnitude and spatial extent of the weekend ozone 

effect in California’s South Coast Air Basin. J. Air 

Waste Manage. Assoc., 2003, 53, 802-815. 

2. Lawson, D.R. Forum – the weekend ozone effect – 

the weekly ambient emissions control experiment. 

EM, 2003, July, 17-25. 

3. Croes, B.E., L.J. Dolislager, L. Larsen, J.N. Pitts. 

Forum – the O3 “weekend effect” and NOx control 

strategies – scientific and public health findings and 

their regulatory implications. EM, 2003, July, 27-35. 

129 
Fuels Technologies FY 2005 Progress Report 

Figure 2. Geographical comparisons of mean Sunday to mean Wednesday daytime (6 a.m. through 3 p.m.) 

concentrations of CO and NOx and mean peak daily one-hour and eight-hour ozone in southeastern Texas. 

The differences were determined from all days, March-October 1998-2003. 

130 
Fuels Technologies FY 2005 Progress Report 

VII Abstracts of Newly Awarded Projects

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Fuels Technologies FY 2005 Progress Report 

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Fuels Technologies FY 2005 Progress Report 

VII.1 Natural Gas Vehicle Cylinder Safety, Training and Inspection 

Clean Vehicle Education Foundation 

The overall object of this project is to increase the understanding of the safe and proper use and 

maintenance of vehicular compressed natural gas (CNG) fuel containers. There is a large and growing number 

of CNG-powered vehicles on the road in North America today. The high-pressure fuel containers they use 

require periodic inspection and maintenance to insure safe and proper operation. This project will identify and 

address CNG cylinder needs related to existing law, codes and standards, available training and inspection 

programs, and assure coordination among vehicle users, public safety officials and training providers. 

Methodology: The project is composed of six separate phases: 

I Public and Industry Awareness Campaign 

II Training Scholarships or Tuition Assistance 

III Evaluation of Current Training and Testing Practices 

IV CNG Cylinder Safety Monitoring and Investigation Activities 

V CNG Cylinder Recertification 

VI Compressed Hydrogen/HCNG Cylinder Safety Considerations 

The information generated by this project will assess current high-pressure fuel container inspection and 

maintenance and provide the basis for potential future changes to existing codes and standards. This 

information will also be useful in assessing the adequacy of codes and standards for high-pressure fuel 

containers for compressed hydrogen and mixtures of compressed hydrogen and natural gas. 

133 
Fuels Technologies FY 2005 Progress Report 

VII.2 Natural Gas Vehicle Roadmap and Data Collection Effort 

Clean Vehicle Education Foundation (CVEF) 

This project will develop a comprehensive roadmap for targeted development of natural gas refueling 

infrastructure projects (compressed natural gas [CNG], liquefied natural gas [LNG] and/or a combination of 

the two) to support successful deployments of light- and heavy-duty natural gas vehicles in niche markets. The 

project will involve public and private stakeholders utilizing the already established CVEF Market Advisory 

Committee as the primary working group. This working group will address the drivers and barriers to the 

successful deployment of natural gas vehicles, research and document the lessons learned from existing 

projects, and develop criteria that allow decision-makers to focus limited resources. Also included in the effort 

is the development and implementation of a plan for the collection of natural gas (CNG and LNG) vehicle fuel 

sales information. A review of the several external efforts currently on-going that collect national and state 

estimates where feasible for CNG/LNG fuel use data in the transportation sector will be made. The work 

addressed will not only be a check and balance of those efforts, but will add the most value by concentrating on 

fuel use data collection efforts for CNG/LNG niche markets (e.g., transit buses, school buses, airport taxis and 

shuttles, short- and long-haul freight carriers, and refuse haulers) and aggregating and reporting the collected 

data at the state and national levels. Both retail and wholesale sales from private and public pumps will be 

included. 

The Natural Gas Vehicle Roadmap will document the drivers and barriers to the successful deployment of 

natural gas vehicles (technical and market based), which includes, at a minimum, identifying regional 

differences and opportunities and the role for new natural gas vehicle and fuel technologies in meeting energy 

and environmental goals; documenting lessons learned from existing projects; describing potential fleet and 

niche market applications; developing criteria that allow decision-makers to focus limited resources and 

leverage investments through partnerships; documenting roles and opportunities for local gas distribution 

companies, fuel providers, and other industry stakeholders (including implementation steps and outreach 

required for public acceptance); and documenting the potential for natural gas infrastructure to build a 

foundation for future hydrogen infrastructure. Electronic versions of the Roadmap will be distributed via 

websites; a limited number of printed copies will be made available. 

The natural gas vehicle fuel use data collection activity will focus on niche market applications (e.g., 

transit buses, school buses, airport taxis and shuttles, short- and long-haul freight carriers and refuse haulers). 

The data collected will be aggregated to the state and national levels, and, as feasible, attributable to Clean 

Cities jurisdictional boundaries. Both retail and wholesale sales from private and public refueling stations will 

be included. A protocol will be established so that data can be updated on an annual basis. 

134 
Fuels Technologies FY 2005 Progress Report 

VII.3 Investigation of Bio-Diesel Fueled Engines under Low-Temperature 

Combustion Strategies 

University of Illinois 

This project will investigate the combustion characteristics of bio-diesel under low-temperature 

combustion (LTC) conditions. Bio-diesel has been found to be a very promising alternative to petroleum 

diesel fuel. It is renewable and is rich with oxygenates which have been shown to reduce soot emissions 

significantly. However, its utilization has been limited to some extent by its higher NOx emissions relative to 

petroleum diesel under conventional direct injection (DI) diesel engine combustion operation. LTC has the 

potential to dramatically reduce NOx emissions while keeping similar fuel efficiency as DI diesel engines. 

Using bio-diesel in LTC engines has the potential to achieve both high efficiency and very low exhaust 

emissions. 

Meeting the challenge of developing and optimizing the combustion processes of bio-diesel fueled LTC 

engines will require a new level of the understanding of the physical phenomena that are common to the DI 

diesel engines and low-temperature combustion engines, which will be strongly affected by the different fuel 

properties, which in turn affect fuel/air mixture preparation, combustion and emissions. In particular, the 

liquid droplet vaporization process in the cylinder is highly transient and complicated due to the 

multi-component fuel effects and the interaction with the in-cylinder turbulent flow and combustion processes. 

It is difficult to evaluate (or control) the impact of the bio-diesel fuel on emissions without detailed knowledge 

of the in-cylinder fuel/air mixing. To date, little if any in-cylinder measurements have been made on such 

bio-diesel fueled LTC engines. The objective of this project is to provide detailed information on (1) bio-diesel 

fuel properties; (2) the effects of bio-diesel fuel properties on fuel-air mixing, ignition, combustion, and 

emissions in LTC engines; (3) knowledge of NOx, soot, hydrocarbon and CO emissions formation in 

bio-diesel LTC engines; (4) the effects of engine operating parameters on the efficiency and emissions 

of bio-diesel LTC engines; and (5) the strategies for reducing exhaust emissions and increasing the efficiency 

of bio-diesel LTC engines. 

A multi-cylinder diesel engine will be used for measuring emissions and performance. A single-cylinder 

research engine based on the same engine geometry, modified for optical access using a Bowditch piston 

arrangement, will be used to study in-cylinder processes using the latest laser diagnostic and multi-dimensional 

modeling techniques. The combined experimental and modeling efforts will provide the useful physical 

insight and detailed quantitative information needed to optimize engine performance and minimize emissions. 

135 
Fuels Technologies FY 2005 Progress Report 

136
Fuels Technologies FY 2005 Progress Report 

VIII Acronyms

°C Degrees Celsius 

ACS American Chemical Society 

A/F Air-fuel ratio 

Ag Silver 

Al2O3 Aluminum oxide; alumina 

ANL Argonne National Laboratory 

APBF-DEC Advanced Petroleum-Based Fuels - 

Diesel Emission Control 

ASME American Society of Mechanical 

Engineers 

ASTM American Society for Testing and 

Materials 

ATDC, atdc After top dead center 

AU, a.u. Arbitrary units 

B20 A blend consisting of 20% biodiesel 

and 80% conventional diesel 

B100 Neat (100%) biodiesel 

Ba Barium 

BaCO3 Barium carbonate 

BC Black carbon 

BMEP Brake mean effective pressure 

BP British Petroleum 

BSNOx Brake-specific oxides of nitrogen 

BTDC Before top dead center 

CA Crank angle 

cad Crank angle degree(s) 

CaFCP California Fuel Cell Partnership 

CARB California Air Resources Board 

cc Cubic centimeter(s) 

CCRT Catalytic continuously regenerating 

trap 

CeO2 Ceric oxide 

CFD Computational fluid dynamics 

CH4 Methane 

CI Chemical ionization 

CIDI Compression ignition direct injection 

cm Centimeter 

CN Cetane number 

CNG Compressed natural gas 

CO Carbon monoxide 

CO2 Carbon dioxide 

CP Cylinder pressure 

CR Compression ratio 

CRC Coordinating Research Council 

CRF Combustion Research Facility 

CVEF Clean Vehicle Education Foundation 

CWI Cummins Westport Inc. 

DCDC 

DCN 

DECSE 

DEER 

deg 

DEM 

DGE 

DI 

DOE 

DPF 

ECD 

ECS 

EGR 

EI 

EO 

EP 

EPA 

EPMA 

ESC 

FCV 

FE 

FID 

FSN 

FT 

FTIR 

ft-lb 

FTP 

FTP-75 

FY 

g 

g/bhp-hr 

g/cc 

GC 

GC/MS 

g/hp-hr 

g/ihp-hr 

g/mi 

GFV 

g/kw-hr 

GM 

gph 

Dilute clean diesel combustion 

Derived cetane number 

Diesel Emission Control Sulfur Effects 

Diesel Engine Emissions Reduction 

Degrees 

Delayed extended main 

Diethylene glycol diethyl ether 

Direct injection 

U.S. Department of Energy 

Diesel particulate filter, diesel particle 

filter 

Emission control device 

Emission control system 

Exhaust gas recirculation 

Electron impact 

Engine-out 

End point 

U.S. Environmental Protection Agency 

Electron probe microanalysis 

European 13-mode, steady-state engine 

test procedure; also known as the 

OICA/ACEA cycle 

Fuel cell vehicle 

Fuel economy 

Flame ionization detector 

Filter smoke number 

Fischer-Tropsch 

Fourier transform infrared 

Foot-pound 

Federal Test Procedure 

Federal Test Procedure for light-duty 

vehicles 

Fiscal year 

Gram(s) 

Gram(s) per brake horsepower-hour 

Gram(s) per cubic centimeter 

Gas chromatography 

Gas chromatography/mass 

spectroscopy 

Gram(s) per horsepower-hour 

Gram(s) per indicated horsepowerhour 

Grams per mile 

Gaseous fuel vehicle 

Gram(s) per kilowatt-hour 

General Motors 

Gallons per hour 

137 
Fuels Technologies FY 2005 Progress Report 

GTL Gas-to-liquid 

H2 Diatomic hydrogen 

H2S Hydrogen sulfide 

HC Hydrocarbon 

HCCI Homogeneous charge compression 

ignition 

HCNG Hydrogen compressed natural gas 

HC-SCR Hydrocarbon selective catalytic 

reduction 

HECC High-efficiency clean combustion 

HFET Highway Fuel Economy Test 

hp, HP Horsepower 

HP High-pressure 

HPDI High-pressure direct injection 

hr Hour 

HRA Home refueling appliance 

HVA Hydraulic valve actuation 

IBP Initial boiling point 

ICTC Interstate Clean Transportation 

Corridor 

IFT Interfacial tension 

IQT Ignition quality tester 

J Joules 

JSAE Japan Society of Automotive 

Engineers 

K Kelvin 

K Potassium 

km Kilometer(s) 

kPa Kilopascal 

L Liter 

LANL Los Alamos National Laboratory 

LFG Landfill gas 

LLNL Lawrence Livermore National 

Laboratory 

LNG Liquefied natural gas 

LNT Lean NOx trap 

LP Low-pressure 

LTC Low-temperature combustion 

LTHR Low-temperature heat release 

MECA Manufacturers of Emission Controls 

Association 

MFB50 Crank angle for 50% completion of 

combustion 

mg Milligram(s) 

μg Microgram(s) 

mi Mile(s) 

min Minute(s) 

MJ/kg Megajoule(s) per kilogram 

ml, mL Milliliter(s) 

μm Micrometer(s) 

mm 

MON 

MOU 

mpg 

ms 

MS 

MSAT 

MY 

N2 

N2O 

N/A 

NAC 

N-CLD 

NETL 

ng 

NG 

NGNGV 

NGV 

NGVTF 

NH3 

nm 

NMHC 

NMR 

NO 

N2O 

NO2 

NOx 

NPBF 

NREL 

O2 

O3 

OEM 

OFCVT 

ORNL 

P 

P 

PAH 

PCCI 

PDU 

PGM 

PM 

PM2.5 

PNNL 

ppbv 

ppm, PPM 

Millimeter(s) 

Motor octane number 

Memorandum of Understanding 

Mile(s) per gallon 

Millisecond(s) 

Mass spectrometer 

Mobile source air toxic 

Model year 

Diatomic nitrogen 

Nitrous oxide 

Not applicable 

NOx adsorber catalyst 

Nitrogen-specific chemiluminescence 

detector 

National Energy Technology 

Laboratory 

Nanogram(s) 

Natural gas 

Next Generation Natural Gas Vehicle 

Natural gas vehicle 

Natural Gas Vehicle Technology 

Forum 

Ammonia 

Nanometer 

Non-methane hydrocarbon 

Nuclear magnetic resonance 

Nitric oxide 

Nitrous oxide 

Nitrogen dioxide 

Oxides of nitrogen 

Non-petroleum based fuel 

National Renewable Energy 

Laboratory 

Diatomic (molecular) oxygen 

Ozone 

Original equipment manufacturer 

Office of FreedomCAR Vehicle 

Technologies 

Oak Ridge National Laboratory 

Phosphorus 

Pressure 

Polyaromatic hydrocarbon 

Premixed charge compression ignition 

Process development unit 

Platinum group metal 

Particulate matter 

Fine particles smaller than 2.5 μm 

Pacific Northwest National Laboratory 

Parts per billion by volume 

Parts per million 

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Fuels Technologies FY 2005 Progress Report 

ppmw Parts per million by weight 

Pt Platinum 

R&D Research and development 

RON Research octane number 

RPM, rpm Revolution(s) per minute 

s Second(s) 

S Sulfur 

SAE Society of Automotive Engineers 

SCAQMD South Coast Air Quality Management 

District 

SCORE Sandia Compression-ignition Optical 

Research Engine 

SCR Selective catalytic reduction 

sec Second 

SI Spark ignition 

SING Spark-ignited natural gas 

SNL Sandia National Laboratories 

SO2 Sulfur dioxide 

SpaciMS Spatially resolved capillary inlet mass 

spectrometer 

SSP Saturated stoichiometric product 

SULEV Super ultra low emission vehicle 

SUV Sports utility vehicle 

SwRI Southwest Research Institute 

T Temperature 

T50 Temperature where 50% of a fuel is 

evaporated during distillation 

TDC Top dead center 

TDI Turbocharged direct injection 

TEM Transmission electron microscopy 

THC Total hydrocarbon 

TIC 

TP 

TPGME 

TUG 

TWC 

UC 

UDDS 

UEGO 

ug 

ULSD 

U.S. 

US06 

USDA 

UTM 

V 

VGT 

VOC 

Vol% 

VVT 

wt 

wt% 

XPS 

XRD 

XRF 

yr 

ZDDP 

Total ion count 

Tailpipe 

Tri-propylene glycol monomethyl 

ether 

Transit Users Group 

Three-way catalyst 

University of California 

Urban Dynamometer Driving Schedule 

Universal exhaust gas oxygen 

Micro-gram(s) 

Ultra-low sulfur diesel 

United States 

An aggressive chassis dynamometer 

emissions test procedure, part of the 

Supplemental Federal Test Procedure 

United States Department of 

Agriculture 

Universal Transverse Mercator 

(mapping projection methodology) 

Volt 

Variable geometry turbocharger 

Volatile organic compound 

Volume percent 

Variable valve timing 

Weight 

Weight percent 

X-ray photoelectron spectroscopy 

X-ray diffraction 

X-ray fluorescence spectroscopy 

Year 

Zinc dialkyldithiophosphate 

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Fuels Technologies FY 2005 Progress Report 

140
Fuels Technologies FY 2005 Progress Report 

IX Author Index

A

Aceves, Salvador M. .............................................76

Alleman, Teresa L. ..............................................111


B

Bunting, Bruce G. ................................39, 44, 85, 94

H

Hayes, R. Robert ...................................................59

L

Lawson, Douglas R. ............................................127


M

McCormick, Robert L. ........................................114


Mueller, Charles J. .................................................65

P

Parish, Richard ......................................................99


Pitz, William J. ......................................................72

R

Rohrbach, Ronald ................................................. 50

S

Sluder, C. Scott ..................................................... 90

Storey, John M. E. ........................................ 55, 119


T

Taylor, Joshua D. .................................................. 81

Thomas, John F. .................................................... 31

Thornton, Matthew J. ..................................... 17, 24

W

Wegrzyn, James .................................................. 104


West, Brian H. ...................................................... 35

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Fuels Technologies FY 2005 Progress Report 

142
Acknowledgement

We would like to express our sincere appreciation to QSS Group, Inc., Oak Ridge National 

Laboratory, and Argonne National Laboratory for their technical and artistic contributions 

in preparing and publishing this report.

In addition, we would like to thank all the participants for their contributions to the programs and all the authors who prepared the project abstracts that comprise this report.
A Strong Energy Portfolio for a Strong America 

Energy efficiency and clean, renewable energy will mean a stronger economy, a cleaner environment, 


and greater energy independence for America. Working with a wide array of state, community, industry, and 


university partners, the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy 


invests in a diverse portfolio of energy technologies.


For more information contact:


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1-877-EERE-INF (1-877-337-3463)


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