reversibility of gasoline sulfur effects

Transcription

API Contract No. 2012-106409
REVERSIBILITY OF GASOLINE SULFUR EFFECTS
ON EXHAUST EMISSIONS
FROM LATE MODEL VEHICLES
June 20, 2013
Prepared for:
American Petroleum Institute
1220 L Street, NW
Washington, DC 20005
www.api.org
Prepared by:
SGS Environmental Testing Corporation
Keith Vertin and Aaron Reek
2022 Helena St. Aurora, CO 80011
(303) 344-5470
www.sgs.com/etc
This page intentionally blank
API 2012-106409 FUEL SULFUR REVERSIBILITY STUDY
REVERSIBILITY OF GASOLINE SULFUR EFFECTS ON
EXHAUST EMISSIONS FROM LATE MODEL VEHICLES
Table of Contents
List of Figures................................................................................................................................................. ii
List of Tables ................................................................................................................................................. iii
Abbreviations and Acronyms ....................................................................................................................... iv
Acknowledgements ....................................................................................................................................... v
1.0
Executive Summary ........................................................................................................................... 1
2.0
Introduction ....................................................................................................................................... 2
3.0
Test Plan for the Fuel Sulfur Reversibility Study ............................................................................... 4
4.0
Fuel Specification and Preparation ................................................................................................... 6
5.0
Vehicle Model Selection and Description.......................................................................................... 8
6.0
Preparation for Testing.................................................................................................................... 12
6.1
Catalyst and Sensor Aging ........................................................................................................... 12
6.2
Chassis Dynamometer Lab and Emissions Measurement ........................................................... 16
6.3
Vehicle Preparation and As-Received Exhaust Emissions ........................................................... 20
7.0
Sulfur Reversibility Study – Individual Vehicle Test Results ............................................................ 22
7.1
API01 2009 Chevrolet Malibu ...................................................................................................... 23
7.2
API02 2012 Honda Civic EX .......................................................................................................... 25
7.3
API03 2012 Hyundai Sonata ........................................................................................................ 27
7.4
API04 2012 Ford Focus ................................................................................................................ 29
7.5
API05 2012 Audi A3 ..................................................................................................................... 31
7.6
API06 2012 Toyota Camry ........................................................................................................... 33
7.7
Comparison of Vehicle Exhaust Temperatures and Emissions ................................................... 35
7.8
Raw Emissions and Catalyst Efficiency Data ................................................................................ 39
7.9
Comparison of API01 Malibu NOx Results with the Umicore Study ........................................... 41
7.10 Reversibility Data Tables ............................................................................................................. 43
8.0
Sulfur Reversibility Study Results - Statistical Analysis.................................................................... 48
8.1
Statistical Analysis Approach ....................................................................................................... 48
8.2
Statistical Analysis Results and Discussion .................................................................................. 51
9.0
Summary and Conclusions .............................................................................................................. 56
10.0 References ....................................................................................................................................... 57
11.0 Appendices ...................................................................................................................................... 59
11.1 Fuel Sulfur Monitoring Results for Emissions Test Fuels ............................................................. 59
11.2 Certificate of Analysis for Emissions Test Fuels ........................................................................... 60
11.3 Catalyst Aging Test Fuel Properties ............................................................................................. 76
11.4 Exhaust and Catalyst Temperature Histograms for Aging Test ................................................... 77
11.5 Dynamometer Equivalent Test Weights and Road Load Coefficients ......................................... 83
11.6 Manufacturer Recommended Motor Oils ................................................................................... 83
11.7 Catalyst Warm-Up and NOx Light-Off for Each Vehicle, Reversibility Sequence, FTP75 ............ 84
11.8 Raw Exhaust Emissions and Catalyst Conversion Efficiency........................................................ 90
11.9 Soot, Particle Number and Size Distribution Reports ................................................................. 98
i
List of Figures
Figure 1. Vehicles Selected for the Gasoline Sulfur Effects Study ................................................................9
Figure 2. Catalyst Aging on JMT Engine Stand: V-8 Engine (Top), Multi-leg Exhaust System (Bottom).... 12
Figure 3. Typical Exhaust System Instrumentation for Catalyst Aging Test .............................................. 14
Figure 4. Air-Fuel Ratio Histogram for Vehicle API01 over the 225 hour Aging Run................................. 14
Figure 5. Exhaust Inlet, Close Coupled Catalyst and Underbody Catalyst Temperature Histograms for
Vehicle API01 over the 225 hour Aging Run............................................................................................... 15
Figure 6. API02 Civic in SGS-ETC Site 2 Chassis Dynamometer Emissions Lab .......................................... 16
Figure 7. Emissions Sampling Arrangement .............................................................................................. 17
Figure 8. Catalyst Bed Temperatures for 2009 Malibu at 5440 feet and 960 feet Elevation – FTP75 ...... 19
Figure 9. Catalyst Bed Temperatures for 2009 Malibu at 5440 feet and 960 feet Elevation – US06 ....... 20
Figure 10. Typical Exhaust System Instrumentation for Vehicle Emissions Tests ..................................... 21
Figure 11. Sulfur Reversibility Test Results, API01 Malibu ........................................................................ 24
Figure 12. Sulfur Reversibility Test Results, API02 Civic ............................................................................ 26
Figure 13. Sulfur Reversibility Test Results, API03 Sonata ........................................................................ 28
Figure 14. Sulfur Reversibility Test Results, API04 Focus .......................................................................... 30
Figure 15. Sulfur Reversibility Test Results, API05 A3 ............................................................................... 32
Figure 16. Sulfur Reversibility Test Results, API06 Camry ......................................................................... 34
Figure 17. Segment of the EPEFE Cycle Used for Catalyst Sulfur Purge .................................................... 35
Figure 18. Catalyst Warm-Up and NOx Light Off Comparison, 10ppm Sulfur Fuel ................................... 37
Figure 19. Soot Emissions Comparison in CVS Diluted Exhaust Stream, 10 and 80 ppm Sulfur Fuels ...... 38
Figure 20. Conversion of Hydrocarbons Across Close Coupled and Underbody Catalysts, Vehicle API05 39
Figure 21. NOx Conversion Across Close Coupled and Underbody Catalysts, Vehicle API03 .................... 40
Figure 22. 2009 Malibu NOx Emissions – Comparison between Umicore and API Fuel Sulfur Studies ..... 42
Figure 23. Sensitivity of API01 Underbody Catalyst NOx Conversion to Fuel Sulfur .................................. 43
Figure 24. Data Distributions for NOx and Soot Emissions ........................................................................ 49
Figure 25. Difference in Mean Emissions and 95% Confidence Intervals for 10 ppm Sulfur Fuel ............. 52
Figure 26. Soot and PN Correlation for Vehicle API04, 10 ppm and 80 ppm Fuels.................................... 53
Figure 27. Difference in Mean Emissions and 95% Confidence Intervals for 10 ppm Sulfur Fuel ............. 54
ii
List of Tables
Table 1. Test Sequence for Each Vehicle in the Sulfur Sensitivity Study ......................................................4
Table 2. Base Fuel Properties and Comparison with California LEV III Certification Fuel Standard .............7
Table 3. Test Fuel Names and Descriptions ..................................................................................................7
Table 4. Vehicle Models and Emissions Certification Label Information .....................................................9
Table 5. Vehicle ID Number, Emissions Control Equipment and Catalyst Summary................................. 10
Table 6. Catalyst Arrangement for Engine Stand Aging Runs .................................................................... 13
Table 7. Median and Peak Catalyst Exposure Temperatures over Aging Period (225 hours) ................... 16
Table 8. As-Received Vehicle Exhaust Emissions, FTP75, Federal Certification Gasoline ......................... 21
Table 9. Typical Exhaust Gas and Catalyst Bed Temperatures for EPEFE Cycle WOT Events .................... 35
Table 10. Median and Peak Catalyst Temperatures for the US06 and FTP75 Cycles, 10ppm Sulfur Fuel . 36
Table 11. Coefficient of Variation for Raw Exhaust Emissions, FTP75, 10 ppm Sulfur Fuel ....................... 41
Table 12. 2009 Malibu SULEV-II PZEV Fuel Sulfur Studies – Catalyst Aging and Test Fuels ....................... 42
Table 13. Fuel Sulfur Reversibility Study Dataset for Analysis, API01 and API02 ...................................... 44
Table 14. Fuel Sulfur Reversibility Study Dataset for Analysis, API03 ........................................................ 45
Table 15. Fuel Sulfur Reversibility Study Dataset for Analysis, API04 ........................................................ 46
Table 16. Fuel Sulfur Reversibility Study Dataset for Analysis, API05 and API06 ...................................... 47
Table 17. Mean Emissions and 95% Confidence Intervals from Statistical Analysis .................................. 55
iii
Abbreviations and Acronyms
API
CALEV3_10
CALEV3_xx
CC, CCC
CFR
CH4
CO
CO2
COV
CPC
CVS
EEPS
EPA
EPEFE
FID
FTP75
GDI
HC
I/M
JMT
LA4
mg
MILs/DTCs
NEDC
NMOG
NOx
ppm
PM
PN
PRLEV3_10
PRLEV3_xx
PSD
PZEV
RVP
SFI
SGS-ETC
SGS-OGC
SRC
SULEV-II
TC
UB, UBC
US06
WOT
California LEV III regular octane gasoline, nominal 10ppm sulfur content
California LEV III regular octane gasoline fuel doped to a sulfur content of xx ppm
Close Coupled or Close Coupled Catalyst
Code of Federal Regulations
Methane
Carbon monoxide
Carbon dioxide
Coefficient of Variation
Condensation Particle Counter
Constant Volume Sampling
Engine Exhaust Particle Sizer
U.S. Environmental Protection Agency
Reference to the sulfur purge drive cycle developed by the European Programme on
Emissions, Fuels and Engine Technologies
Flame Ionization Detector
Federal Test Procedure consisting of a 3-phase drive cycle
Gasoline Direct Injection
Total hydrocarbons
Inspection/Maintenance readiness state in on-board diagnostic system
Johnson Matthey Vehicle Testing and Development, Taylor, Michigan
2-phase drive cycle also known as the FTP72 or Urban Dynamometer Driving Schedule
Milligrams
Manufacturer Indicator Lamp or Diagnostic Trouble Codes
New European Driving Cycle
Non Methane Organic Gases, estimated as NMHC*1.1012 for E10 gasoline
Oxides of nitrogen
Parts per million
Particulate Matter, measured gravimetrically in this study
Particle Number, for accumulation mode particles measured per Euro 6 PMP protocol
California LEV III premium octane gasoline, nominal 10ppm sulfur content
California LEV III premium octane gasoline fuel doped to a sulfur content of xx ppm
Particle Size Distribution
Partial Zero Emissions Vehicle category within California LEV II Standards
Reid Vapor Pressure
Sequential multi-port fuel injection system
SGS Environmental Testing Corporation, Aurora, Colorado
SGS Oil, Gas and Chemical Analytical Laboratory, Deer Park, Texas
EPA Standard Road Cycle
Super Ultra Low Emissions Vehicle category within California LEVII Standards
K-type thermocouple
Underbody or Underbody Catalyst
US06 Supplemental Federal Test Procedure, a high speed and acceleration drive cycle
Wide Open Throttle
iv
Acknowledgements
The authors wish to thank the following individuals for their significant contributions to this study:
Myles Weddington, Brad Kotch, Dave Reeves, David Meyer, Jeff Reed, David Casias, Joe Schmidt, Brad
Farmer and Krystal Lewis at SGS Environmental Testing Corporation in Aurora Colorado; and Thomas
Villeneuve and Dominic Margitan for their catalyst aging expertise at Johnson Matthey Testing in Taylor
Michigan. Special thanks go to Gary Fenton of Air Academy Associates for review and discussion of the
statistical analysis approach.
The authors also acknowledge the technical contributions and support from participating API members:
David Lax
King Eng
James Uihlein
James Williams
Garry Gunter
Mani Natarajan
Matt Watkins
Phil Heirigs
Fred Cornforth
Jim Simnick
Shell
Chevron
Phillips 66
Marathon Petroleum
ExxonMobil
Chevron
Phillips 66
BP
v
1.0 Executive Summary
On March 29, 2013 the US Environmental Protection Agency (EPA) released a proposed rule for Tier 3
Motor Vehicle Emission and Fuel Standards.
The proposed NMOG+NOx tailpipe standards for lightduty vehicles represent approximately an 80% reduction from today’s fleet average. EPA is also
proposing that federal gasoline contain no more than 10 ppm of sulfur on an annual average basis by
2017. There are several proposals with regards to the fuel sulfur cap, including either to maintain the
current 80 ppm refinery gate and 95ppm downstream caps or to lower them to 50 and 65 ppm,
respectively. Currently, federal regulations limit the sulfur content of gasoline to a 30 ppm annual
average and a maximum cap of 80 ppm.
Sulfur is known to poison precious metal based three-way catalyst exhaust emission control systems.
The impact of gasoline sulfur on older vehicle technologies ranging from Tier 0 to ULEV is relatively well
understood.
In contrast, there is a lack of test data on the sensitivity and reversibility of very low emitting vehicles
(e.g., SULEV-II, PZEV, and Tier 2 Bin 2) to gasoline sulfur, especially for vehicles aged to full useful life.
Further research is needed to evaluate late model vehicle emissions using the low levels of fuel sulfur
proposed in the EPA Tier 3 rule.
This present study has tested six late model vehicles to determine if the exhaust emissions effects
caused by exposure to 80 ppm sulfur fuel were reversible, after the vehicle was refueled with 10 ppm
sulfur fuel. The reversibility test sequence included three segments: four baseline emissions tests run
on 10 ppm sulfur fuel, three high sulfur fuel exposure tests using 80 ppm fuel, and three tests run after
the vehicle was switched back to 10 ppm fuel. Each vehicle was driven 125 miles during the initial
baseline tests using 10 ppm sulfur gasoline, followed by approximately 372 miles of operation on the 80
ppm sulfur gasoline, and 72 miles after refueling with 10 ppm sulfur fuel. The base fuel was a California
LEVIII certification gasoline containing 10%vol ethanol. The 80 ppm fuel was produced by doping the
base fuel with a representative mixture of sulfur compounds.
Test vehicles included a 2009 Chevrolet Malibu, 2012 Honda Civic, 2012 Hyundai Sonata, 2012 Ford
Focus, 2012 Audi A3, and 2012 Toyota Camry. All vehicles were certified to California SULEV-II / PZEV
emissions standards except the Camry, which was Federal Tier 2 Bin 5. The vehicles represented a wide
range of emission control technologies. The Sonata, Focus and A3 were equipped with wall-guided
gasoline direct injection engines. The vehicles were selected to represent the latest in powertrain and
emissions controls technology, and were tested as a surrogate for EPA Tier 3 vehicles which are not yet
commercially available.
New catalytic convertors and sensors were procured and aged on an engine stand to the equivalent of
120,000 to 150,000 miles. The aged catalysts and sensors were then installed on six vehicles for
emissions testing.
FTP75 emissions tests were performed. Raw gaseous emissions were measured to quantify catalyst
efficiency, and bag dilute emissions were collected to determine accurate mass emissions for analysis.
Particulate matter, soot mass, particle number, and particle size distribution measurements were also
made.
Page 1
The vehicles responded quite differently to changing sulfur content.
Emissions trends, catalyst
temperature data, catalyst warm-up information and particulate comparisons are made in the report.
Five of the six vehicles tested using 10 ppm sulfur fuel had emissions under the proposed EPA Tier 3 Bin
30 FTP75 standard of 0.03 g/mile for NMOG+NOx.
This study aimed to provide independent and objective test results to the API for use in the EPA Tier 3
rule making process. The following conclusions were reached:

Gaseous exhaust emissions were higher for the vehicles conditioned and tested using 80 ppm
sulfur fuel, relative to baseline tests run using 10 ppm fuel. Mean emissions increased for
vehicles run on the 80 ppm fuel as follows, with greater than 95% confidence:
o Fleet average NMOG increased by 20% (0.002 g/mile change)
o Fleet average NOx increased by 58% (0.006 g/mile change)
o Fleet average CO increased by 31% (0.078 g/mile change)
o Vehicle API02 (Civic) CO emissions increased by 54% (0.083 g/mile change)
o Vehicle API03 (Sonata) NOx emissions increased by 74% (0.004 g/mile change), noting
that mean emissions of 0.009 g/mile remained well under the SULEV-II standard

For the fleet of six vehicles, average soot and PN emissions were not statistically different for 80
ppm fuel compared to 10 ppm fuel results. Only vehicle API03 (Sonata), the highest PM emitter
in the study, had higher soot and PN emissions using 80 ppm fuel:
o Vehicle API03 (Sonata) soot emissions increased by 11% (0.41 mg/mile change)
o Vehicle API03 (Sonata) PN emissions increased by 17% (9.6x1011 #/mile change)

For each vehicle tested on 10 ppm sulfur fuel, the NMOG, NOx, CO, Soot and PN emissions were
found to be reversible following exposure to 80 ppm sulfur fuel. There was greater than 95%
confidence that the differences in the mean emissions values measured before and after the
high sulfur fuel exposure were not statistically different.

For the fleet of six vehicles combined, the NMOG, NOx, CO, Soot and PN emissions were found
to be reversible following exposure to 80 ppm sulfur fuel.

Vehicles equipped with GDI engines had about five to seven times higher soot mass and particle
number emissions on average compared to the SFI-equipped vehicles.

Vehicles equipped with GDI engines had very high variability in soot and PN emissions. The
vehicle emissions variability was shown to be far larger than the fuel sulfur effect under study.
2.0 Introduction
On March 29, 2013 the US Environmental Protection Agency (EPA) released a proposed rule for Tier 3
Motor Vehicle Emission and Fuel Standards [Ref. 1]. The proposed NMOG+NOx tailpipe standards for
light-duty vehicles represent approximately an 80% reduction from today’s fleet average. A 70%
reduction in particulate matter (PM) standards is also proposed.
Many of the proposed Tier 3
standards are harmonized with California LEV III standards.
Page 2
EPA is also proposing that federal gasoline contain no more than 10 ppm of sulfur on an annual average
basis by 2017. There are several proposals with regards to the fuel sulfur cap, including either to
maintain the current 80 ppm refinery gate and 95 ppm downstream caps or to lower them to 50 and 65
ppm, respectively. Currently, federal regulations limit the sulfur content of gasoline to a 30 ppm annual
average and a maximum cap of 80 ppm.
Sulfur is known to poison precious metal based three-way catalyst exhaust emission control systems. A
number of studies were conducted by industry and government agencies in the US, Europe and Japan in
the late 1980s and during the 1990s to evaluate the sensitivity of gasoline vehicle exhaust emissions to
changes in fuel sulfur content as well as the reversibility of the sulfur poisoning effect. In 1991 the
Auto/Oil Air Quality Improvement Research Program demonstrated the sulfur poisoning effect was
reversible [Ref. 2]. That is, following exposure to high sulfur gasoline the catalyst performance
recovered when switching back to lower sulfur gasoline.
In the European EPEFE program [Ref. 3],
researchers tested fuels containing 18 and 382 ppm sulfur, and reported that benefits of lower sulfur
fuel were strongly dependent on the precious metal formulation used for the catalyst coatings. The
Coordinating Research Council evaluated the effect of driving cycle on catalyst reversibility using fuels
with 30 and 630 ppm sulfur [Ref. 4]. The study included a comprehensive statistical analysis that
concluded the poisoning effect was completely or partially reversible. Consequently, the impact of
gasoline sulfur on vehicle technologies ranging from Tier 0 to ULEV is relatively well understood.
In contrast, there is a lack of test data on the sensitivity of very low emitting vehicles (e.g., SULEV-II,
PZEV, and Tier 2-Bin 2) to gasoline sulfur, and the reversibility of those effects. One study, conducted
by Umicore Autocat USA [Ref. 5], measured the impact of test fuels containing 3 ppm and 33 ppm sulfur
on NOx emissions from only one vehicle - a 2009 model year PZEV Malibu. Results were only reported
for the underbody catalyst. In addition to measuring sulfur sensitivity, the authors also found that use
of a high exhaust flow/high engine load driving cycle such as the US06 reversed the sulfur poisoning
associated with operation on 33 ppm sulfur fuel.
Previous research has shown that both sulfur sensitivity and sulfur reversibility are influenced by a
number of vehicle operating characteristics (e.g., air/fuel ratio control, catalyst temperatures) and
emission control system design, configuration and catalyst formulation. In contrast, the emissions of
late model vehicles to low sulfur levels is not well understood for very low sulfur fuels, and especially for
vehicles aged to full useful life. Further research is needed to evaluate late model vehicle emissions
using the low levels of fuel sulfur proposed in the EPA Tier 3 rule.
This present study has tested six late model vehicles to determine if the exhaust emissions effects
caused by exposure to 80 ppm sulfur fuel were reversible, after the vehicle was refueled with 10 ppm
sulfur fuel. The reversibility test sequence included four baseline tests run on 10 ppm sulfur fuel, three
high sulfur fuel exposure tests using 80 ppm fuel, and three tests after the vehicle was switched back to
10 ppm fuel. The base fuel was a California LEVIII certification gasoline containing 10%vol ethanol. The
80 ppm fuel was produced by doping the base fuel with a mixture of sulfur compounds.
120,000 to 150,000 miles, using an aging fuel with a sulfur range of 18.5 to 43 ppm. The aged catalysts
and sensors were then installed on six vehicles for emissions testing. FTP75 emissions tests were
performed. The results from this sulfur reversibility study are discussed in this report.
Page 3
3.0 Test Plan for the Fuel Sulfur Reversibility Study
The reversibility of fuel sulfur effects on vehicle exhaust emissions was studied using a protocol similar
to previous research [Ref. 4, 5]. The dynamometer test sequence was designed to allow comparison of
results with the 2009 Malibu PZEV tested using “Test Combination Two” from [Ref. 5].
120,000 to 150,000 miles (Section 6.1). The aged catalysts and sensors were then installed on the late
model vehicles for testing. Each vehicle was then tested using a base fuel with 10 ppm sulfur
concentration, exposed to 80ppm fuel and tested, and then retested on 10ppm fuel. The fuels and
vehicles are described in Sections 4 and 5, respectively. The objective of the experiment was to
determine if the vehicle exhaust emissions from tests run using 10 ppm sulfur gasoline were statistically
different following the exposure to 80 ppm sulfur fuel. The test sequence run for each vehicle is shown
in Table 1.
Table 1. Test Sequence for Each Vehicle in the Sulfur Sensitivity Study
Description
Procedure
Catalyst Sulfur Purge, 10ppm Sulfur Fuel
Double Drain and 70% Refill
EPEFE + 2 LA4 Sulfur Purge and Conditioning Cycles
12 to 24 Hour Soak
FTP75 Emissions Test
2 LA4 + 1 US06 Preparation Cycle
12 to 24 Hour Soak
1 US06 Preparation Cycle
12 to 24 Hour Soak
12 to 24 Hour Soak
300 Miles on Dynamometer, Standard Road Cycle
70% Refill
12 to 24 Hour Soak
12 to 24 Hour Soak
12 to 24 Hour Soak
12 to 24 Hour Soak
12 to 24 Hour Soak
12 to 24 Hour Soak
Baseline Emissions, 10ppm Sulfur Fuel
Exposure to 80ppm Sulfur Fuel
Establish Degree of Reversibility, 10ppm Sulfur Fuel
Miles
Cumulative
Miles for
Segment
42.2
11.1
22.9
11.1
8.0
11.1
8.0
11.1
125.4
300.0
22.9
11.1
8.0
11.1
8.0
11.1
372.1
22.9
11.1
8.0
11.1
8.0
11.1
72.1
Page 4
The test sequence began with an EPEFE cycle consisting of ten WOT events to elevate exhaust and
catalyst temperatures for sulfur purge. Previous studies have shown the EPEFE cycle is an effective
means for catalyst sulfur purge. The EPEFE + 2 LA4 cycles served to condition all vehicles uniformly
using 10 ppm low sulfur, prior to the baseline emissions tests.
The purpose of the four baseline tests was to establish vehicle exhaust emissions using the 10 ppm low
sulfur fuel, following the catalyst sulfur purge and prior to the 80 ppm sulfur fuel exposure. The baseline
emissions were the basis for comparison, used to quantify fuel sulfur sensitivity and reversibility effects
for the tests that followed.
A US06 prep cycle was performed in lieu of an LA4 prep cycle, prior to each soak period and FTP75
emissions test. The LA4 and FTP75 cycles used for emissions certification purposes reach a top vehicle
speed of only 56.7 mph, and exhaust temperatures are low in comparison to other chassis
dynamometer cycles. Therefore, repeated dynamometer testing using the LA4 and FTP75 cycles was
not necessarily representative of real-world driving. The US06 cycle was developed to address the
shortcomings with the FTP75 test cycle, to better represent higher speed and higher acceleration driving
behavior. Data from the US Federal Highway Administration show that nearly 46% of the average daily
vehicle miles of travel at posted speeds of 60 mph or higher occurs on urban roads [Ref. 6]. To better
represent real-world driving behavior, the reversibility test sequence used in this study included
alternating US06 and FTP75 cycles, to encompass both higher speed and lower speed vehicle operation.
Following the change to 80ppm fuel, each vehicle was conditioned on the chassis dynamometer for 300
miles using the EPA Standard Road Cycle. Three emissions tests were then run to determine the
sensitivity of vehicle exhaust emissions to catalyst poisoning that occurred during exposure to the 80
ppm sulfur fuel.
The vehicle fuel tank was then drained and refilled with 10 ppm sulfur fuel and triplicate emissions tests
were run. These final tests were performed to determine if the exhaust emissions effects caused by
80ppm sulfur fuel exposure were reversible. That is, the exhaust emissions were compared with the
baseline emissions, to determine if there were any statistical differences in results before and after the
80ppm fuel exposure.
Special care was taken to ensure fuel purges were complete and the vehicle was conditioned on each
fuel before emissions testing began. The start of the sequence included a double drain and fuel fill,
followed by an EPEFE sulfur purge cycle and two LA4 cycles. The EPEFE cycle consisted of a series of
ten WOT accelerations that significantly elevated the exhaust temperatures to promote sulfur purge
from the catalyst [Ref. 7]. The subsequent LA4 cycles served as a prep cycle for conditioning the vehicle
prior to emissions testing. Fuel drains were performed at the fuel rail to ensure a complete drain.
The test fuel and sulfur content were carefully controlled for the experiment. Fuel sulfur concentration
was held within a ±2ppm tolerance for all test fuels (Section 4). Some other inputs that effected
emissions responses are included below, with control measures noted in parentheses:





Vehicle model
Engine out emissions (consistent fuel conditioning and prep cycle used)
Catalyst conversion efficiency (consistent fuel conditioning and prep cycle used)
Driver (same driver used for nearly all tests, no driver violations accepted)
Lab-to-lab variability (same chassis dyno emission lab used for all tests)
Page 5

Day-to-day lab variation, drift (calibration procedures and data quality control)
The primary responses of interest for the reversibility analysis included FTP75 weighted NMOG, NOx,
CO, MPG, soot mass, and Particle Number (PN). All gaseous emissions were measured from CVS sample
bags, and particulate measured from a full dilution tunnel. NMOG emissions were estimated from
NMHC measurements, per Section 6.2. Many other measurements were made for each phase of the
FTP75 emissions test, and are cited in the results section and Appendix of the report.
4.0 Fuel Specification and Preparation
The base fuel for the study was California LEV III certification gasoline [Ref. 8]. This specification has 8
to 11 ppm sulfur, and nominal ethanol content of 10%vol. The certification fuel has a regular and
premium octane specification. The antiknock index, (R+M)/2, is 87 to 88.4 for regular unleaded and 91
minimum for premium unleaded.
Five of the six vehicles in the study were approved by the manufacturers for operation on regular octane
fuels (Section 5). One vehicle had a turbocharged engine and was selected to increase the diversity of
powertrain technology to be tested. The turbocharged engine required premium octane fuel.
Therefore, regular and premium octane base fuels were procured for the study.
At the start of the project, the California LEVIII certification fuel was not commercially available. The
base fuels were therefore made-to-order fuel batches formulated specifically for this project. The base
fuels were ordered with 10 ppm sulfur content and a TOP TIER detergent additive. The base fuel
properties are compared with the California LEVIII specification in Table 2. Fuel property results are
provided for regular and premium octane base fuels. Data from the certificate of analysis (Haltermann)
and from an independent laboratory (SGS-OGC) are presented. Most fuel property results were within
the specification, but a few properties were at or just over limit.
A mixture of sulfur compounds was added to the base fuels to prepare the test fuels with 80 ppm sulfur
concentration. The sulfur mixture consisted of 4 wt% dimethyldisulfide, 23 wt% thiophene, and 73 wt%
benzothiophene, representing the types and distribution of sulfur compounds present naturally in
gasoline [Ref. 9]. Four test fuels were prepared for the project, with identifying names per Table 3.
The test fuels were dispensed into drums. Because fuel sulfur was a critical control parameter in the
study, the fuel sulfur content in the drummed fuel was monitored. Samples were drawn from multiple
drums and sent for analysis (Appendix 11.1). The test fuels all had sulfur concentration within ±2ppm of
the nominal value, and well within the ±3ppm tolerance set for the study.
The certificate of analysis for each fuel is provided in Appendix 11.2.
Page 6
Table 2. Base Fuel Properties and Comparison with California LEV III Certification Fuel Standard
Fuel Name --->
Laboratory --->
Distillation
IBP
10%
50%
90%
EP
Sulfur
RVP
Ethanol
Lead
Unwashed Gum Content
Solvent Washed Gum Content
Copper Strip Corrosion
ASTM
Method
D86
D5453
D5191
D4815
D3237
D381
D381
D130
D4814
Silver Strip Corrosion
Annex A1
Oxidation Stability
D525
Density @ 60F
D4052
Carbon
D5291
Hydrogen
D5291
Oxygen
D4815
Aromatics
D1319
Saturates
D1319
Olefins
D1319
Multi-substituted Alkyl Aromatic HC D5769
RON
D2699
MON
D2700
D2699
Antiknock Index (R+M)/2
/D2700
D2699
Sensitivity
/D2700
Auto Vapor/Liquid Ratio
D5188
Net Heating Value
D240
Phosphorous
D3231
Benzene
D5580
MTBE
D4815
Units
REGULAR OCTANE
CALEV3_10
CALEV3_10
Haltermann
SGS-OGC
PREMIUM OCTANE
PRLEV3_10
PRLEV3_10
Haltermann
SGS-OGC
F
F
F
F
F
ppm
psi
%vol
g/gal
mg/100ml
mg/100ml
Rating
107
137
214
316
352
9
7.2
9.8
None
8.4
<0.5
1a
109.9
138.6
212.4
314.2
345.9
9
7.35
9.64
<0.01
16.5
<0.5
1a
109
136
212
316
357
9
7.2
10.2
None
19.5
<0.5
1a
108.9
138.2
208
314.1
349.5
9
7.25
10.08
<0.01
15.5
<0.5
1a
Rating
min
g/cm3
%mass
%mass
%mass
%vol
%vol
%vol
%vol
Rating
Rating
NA
1000+
0.7496
82.88
13.65
3.6
20.9
NA
1000+
0.7465
82.39
13.82
3.76
21.9
4.9
14
92.3
83.4
0
>240
0.7493
82.2
13.4
3.52
22.7
61.5
6.2
NA
92.4
84
4.4
13
97.8
88
0
>240
0.7464
81.9
13.6
3.7
21.1
62.4
6.5
NA
98.2
87.8
Rating
87.85
88.2
92.9
93
Rating
Rating
BTU/lb
g/gal
%vol
%vol
8.9
NA
18027
None
0.6
None
NA
137
NA
NA
NA
NA
9.8
NA
18118
None
0.7
None
NA
137
NA
NA
NA
NA
CA LEVIII
Specification
130-150
205-215
310-320
390 max
8-11
6.9-7.2
9.8-10.2
0.1 max
3 max
1
1000 min
3.3-3.7
19.5-22.5
4-6
13-15
87-88.4 (reg),
91 min (prem)
7.5 min
0.005 max
0.6-0.8
0.05 max
Table 3. Test Fuel Names and Descriptions
Fuel Name
CALEV3_10
CALEV3_80
PRLEV3_10
PRLEV3_80
Description
Regular Octane Base Fuel, California LEV III Specification, 10ppm Sulfur
Regular Octane Base Fuel doped to 80ppm Sulfur
Premium Octane Base Fuel, California LEV III Specification, 10ppm Sulfur
Premium Octane Base Fuel doped to 80ppm Sulfur
Page 7
5.0 Vehicle Model Selection and Description
This study differs from previous programs in that the focus is to test the latest technology vehicles on
very low sulfur gasoline. API specified the six vehicle models for testing were to have the following
emissions certifications:



One SULEV-II / PZEV vehicle, specifically the 2009 Chevrolet Malibu equipped with a 2.4L engine
to allow comparison with testing performed at Umicore Autocat [Ref. 5]
Four vehicles certified to meet either the Federal Tier 2, Bin 2 exhaust emission standards or the
California SULEV-II / PZEV exhaust emissions standards
One vehicle to represent a typical in-use Federal Tier 2 Bin 5 model
The vehicles were selected to represent the latest in powertrain and emissions controls technology, and
were tested as a surrogate for EPA Tier 3 vehicles which are not yet commercially available. The
preference was to select late model vehicles to represent a range of exhaust emission control system
design configurations available on high selling models. The vehicles were to have accumulated between
5,000 to 10,000 miles of customer driving before testing. An exception was made for the 2009 Malibu,
where a mileage between 10,000 and 20,000 miles was sought because all candidate vehicles were
approximately three years of age at the time of recruitment.
Candidate vehicles were identified by searching for models meeting these emissions standards using the
US EPA 2012 emissions database [Ref. 10]. From this search, all candidate vehicles certified to the
SULEV-II / PZEV emissions standard were equipped with four cylinder engines.
In 2010, EPA and NHTSA introduced a final rule to jointly regulate greenhouse gas emissions and
corporate average fuel economy. In response to increasing fuel economy requirements, there have
been many new vehicle models introduced with gasoline direct injection (GDI) engines in the United
States. Because movement to more fuel efficient GDI engine technology is expected to continue in the
US, it was important to represent GDI technology in the study.
The vehicle models selected for the study are listed in Table 4 and shown in Figure 1. Five of the six
vehicle models were certified to the California SULEV-II / PZEV emissions standards. Several of the
vehicle models had the engine and evaporative family certified to both California and Federal emissions
standards (Table 4). PZEV certification was verified from the vehicle emissions label. Three vehicle
models were equipped with sequential multiport fuel injection (SFI) engines, and three with GDI
engines. All vehicles in the study had stoichiometric combustion following warm-up, and employed
three way catalyst technology.
All vehicles except the Audi A3 were approved for operation on regular unleaded gasoline. For the
turbocharged Audi A3, the manufacturer recommended premium unleaded fuel. The Audi A3 was
selected because there was high interest to include a turbocharged GDI in the study to expand the
diversity of powertrain technology to be tested. Turbocharging and the effect of higher exhaust flow
rates on catalyst performance were of interest. The inclusion of this model also meant that premium
test fuels needed to be included in the study.
The Toyota Camry was chosen to represent Tier 2 Bin 5 vehicle technology, in part because it was
available with a V6 engine and added further diversity to the powertrain technology to be tested. The
Page 8
Honda Civic EX was one of only two non-hybrid vehicle models certified to federal Tier 2 Bin 2 in 2012,
according to the EPA database available at that time.
Table 4. Vehicle Models and Emissions Certification Label Information
Control Model
Number Year
Make
Model
Engine
Family Code
Evaporative
Emissions
Family Code
API01
2009
Chevrolet
Malibu
9GMXV02.4026
9GMXR0123702
API02
2012
Honda
Civic EX
CHNXV01.8VC2
CHNXR0111VZA
API03
2012
Hyundai
Sonata
CHYXV02.4YPC
CHYXR0155PPX
API04
2012
Ford
Focus
CFMXV02.0VZ2
CFMXR0110GBX
API05
2012
Audi
A3
CADXV02.03PA
CADXR0110237
API06
2012
Toyota
Camry
CTYXV03.5BEC
CTYXR0115A12
Engine
2.4L
SFI
1.8L
SFI
2.4L
GDI
2.0L
GDI
2.0L Turbo
GDI
3.5L V6
SFI
Automatic
Transmission
No. Gears
6
5
Emissions
Certification Standard
California LEV-II SULEV
and Federal Tier 2 Bin 5
6
6
6
6
Federal Tier 2 Bin 5
Figure 1. Vehicles Selected for the Gasoline Sulfur Effects Study
The following inspections and checks were made for each vehicle before committing to its procurement:







Odometer between 5,000 and 10,000 miles (2009 Malibu between 10,000 and 20,000 miles)
Confirm vehicle never in accident and clean CarFax history
Confirm no active or pending MILs/DTCs
Vehicle in I/M readiness state
Inspect tires, belts and hoses
Inspect for any obvious vehicle modifications or tampering
Inspect exhaust system and perform leak check
Page 9


Inspect evaporative emissions system, perform pressure decay check
Perform road load derivation, and a preliminary cold start FTP75 emissions cycle using the
vehicle’s street fuel to assess emissions
The five vehicles meeting SULEV-II standards were recruited from California and transported to SGS-ETC
by car carrier for testing. The vehicle ID numbers, starting mileage, emissions control technology from
the certification label, and catalyst arrangement are shown in Table 5. All vehicles except the Honda
Civic EX employed a close coupled catalyst and underbody catalyst combination.
Table 5. Vehicle ID Number, Emissions Control Equipment and Catalyst Summary
Control Model Make and
Number Year Model
Chevrolet
API01
2009
Malibu
Honda
API02
2012
Civic EX
Hyundai
API03
2012
Sonata
Ford
API04
2012
Focus
Audi
API05
2012
A3
Toyota
API06
2012
Camry
Vehicle ID No. (VIN)
Odometer
(miles)
Engine
Equipment on Emissions Label
Catalyst Arrangement
1G1ZH57B79F186689
10981
2.4L I4
SFI, HO2S, TWC, AIR
One close coupled, one underbody
2HGFB2F90CH529133
5823
1.8L I4
TWC, AF SENSOR, HO2S, EGR, SFI
One close coupled
5NPEB4AC3CH365795
6845
2.4L I4
DFI, HO2S(2), WU-TWC, TWC
1FAHP3F28CL155154
5000
2.0L I4
TWC, H2OS, DGI, HAFS
WAUKFAFM8CA000802
9028
2.0L I4
Turbo
DFI,TWC(2),HO2S(3),Air, CAC, TC, DOR One close coupled, one underbody
4T1BK1FK5CU514551
5057
3.5L V6
SFI, 2A/FS, 2WU-TWC, 2HO2S, TWC
Two close coupled, one underbody
The powertrain and emissions control technology is summarized below for each vehicle. Emissions
control equipment was determined from the vehicle emissions labels, from CARB Executive Orders for
emissions certifications, and from information published by the manufacturer. The number of
substrates, substrate size, cell geometry and material could only be determined by cutting the catalyst
cans open and was not completed at the time of this report.
API01 2009 Chevrolet Malibu
 2.4L “LE5” I-4 engine
Power: 169hp@6400rpm, Torque: 160lb-ft@4500rpm
Sequential Multi-Port Fuel Injection
Compression ratio = 10.4:1
16 valve, DOHC variable valve timing
 Air injection/rich operation for fast catalyst light-off [Ref. 5]
 Heated oxygen sensor
 Three way catalysts: one close coupled catalyst, one underbody catalyst
API02 2012 Honda Civic EX
 1.8L “i-VTEC” I-4 engine
16 valve, SOHC variable valve timing
 Exhaust Gas Recirculation
 Heated air-fuel ratio sensor
Page 10


Heated oxygen sensor
Three way catalyst: one close coupled catalyst
API03 2012 Hyundai Sonata
 2.4L “Theta” I-4 engine
Gasoline Direct Injection, wall guided type
 Late injection for fast catalyst light off
 Two heated oxygen sensors
API04 2012 Ford Focus
 2.0L “Ti-VCT” I-4 engine
 Peak injection pressure of 2150 psi
 Heated air-fuel ratio sensor
 Heated oxygen sensor
API05 2012 Audi A3
 2.0L “FSI” I-4 engine
Power: 200hp@5100rpm, Torque: 207lb-ft@1800-5000rpm
Turbocharged and intercooled
 Stratified lean operation on start and air injection for NMOG reduction [Ref. 11]
 Three heated oxygen sensors
 Direct ozone reduction, or DOR, pertains to vehicle radiator coatings and not the
powertrain
API06 2012 Toyota Camry
 3.5L “VVT-i” V-6 engine
 Two heated air-fuel ratio sensors
 Two heated oxygen sensors
 Three way catalysts: two close coupled catalysts, one underbody catalyst
Page 11
6.0 Preparation for Testing
6.1
Catalyst and Sensor Aging
New catalytic convertors and exhaust system sensors were procured for all vehicles and aged on an
engine test stand to the equivalent of 120,000 to 150,000 miles. All exhaust parts used for aging were
stock and procured from authorized dealerships. Johnson Matthey Testing (JMT) in Taylor, Michigan
provided the test protocol and performed the catalyst and sensor aging.
The engine test stand utilized an 8.1L Chevrolet V8 Engine with exhaust manifolds joined to a custom
quad leg exhaust system (Figure 2). The engine exhaust was split into four legs to allow the aging of
catalysts from multiple vehicles simultaneously.
Exhaust sample feeds, thermocouples and flow
controllers were instrumented into this system in their respective positions to support the precise
control of the aging cycle.
API03
Close Coupled Cat
Exhaust
Flow
API03
Underbody Cat
Vehicle
Sensors
API04
Close Coupled Cat
API04
Underbody Cat
Figure 2. Catalyst Aging on JMT Engine Stand: V-8 Engine (Top), Multi-leg Exhaust System (Bottom)
Page 12
The catalysts from all six vehicles were aged in two dynamometer runs. Where possible, manufacturer
hardware including interconnecting pipes, flex pieces and flanges were used in the test set-up. The
characteristic length between the close coupled catalyst and underbody catalyst was maintained. The
catalyst arrangement for each dynamometer run is summarized in Table 6. Exhaust system sensors
were included in the aging process. Since the sensors had wires and plastic connectors in close
proximity to the exhaust pipe, tube assemblies were designed to cool the sensors with shop air to avoid
melting during this high temperature test (visible in Figure 2).
Table 6. Catalyst Arrangement for Engine Stand Aging Runs
Exhaust
Leg
1
2
3
4
Engine Stand Aging Run #1
Engine Stand Aging Run #2
API01 Close Coupled Cat, API01 Underbody Cat
API02 Close Coupled Cat
API06 Left Bank Close Coupled Cat, API06 Underbody Cat
API06 Right Bank Close Coupled Cat
None
Protocols to accelerate the aging of automotive catalysts on the engine test stand have been in use for
many years and have evolved over time [Ref. 12,13,14]. The Rapid Aging Test, or RAT-A, utilizes a multimode sequence to produce elevated exhaust temperatures to thermally age the catalyst.
Manufacturers have developed proprietary catalyst aging tests based on RAT-A to correlate the test
results with real-world experience. For this study, it was not feasible to use proprietary aging cycles for
each of the vehicle systems. The CARB-modified RAT-A cycle was chosen as a contemporary method for
aging all vehicle systems in this study [Ref. 14]. The aging cycle parameters used were:
CARB Modified RAT-A: Four-Mode Aging
 Mode 1 = 40 seconds engine out condition @ stoichiometric fuel-air ratio
Inlet temperature @ 825°C (± 20°C)
80 scfm exhaust flow per converter
 Mode 2 = 6 seconds @ fuel-rich operation
3.0% CO (± 0.3%).
 Mode 3 = 10 seconds @ fuel-rich operation (same as Mode 2) with secondary air injection
3.0% O2 (± 0.3%).
 Mode 4 = 4 seconds engine out condition @ stoichiometric fuel-air ratio
Secondary air injection operation (same as Mode 3)
 225 hours cycle time, equivalent to 120,000 to 150,000 miles
The exhaust system included laboratory sensors for controlling the engine test stand. Typical exhaust
system instrumentation is shown in Figure 3. Note that K-type thermocouples (designated as “TC”)
were inserted radially through the can, one inch from the front face and rear face of the substrate per
standard industry practice.
An alcohol-free gasoline with 91 antiknock index was used for the catalyst aging tests. Several batches
of fuel were used during the aging period, and fuel properties for each batch are summarized in
Appendix 11.3. Aging fuel sulfur content varied from 18.5 to 43 ppm.
Page 13
Figure 3. Typical Exhaust System Instrumentation for Catalyst Aging Test
Precise control of air fuel ratio and secondary air injection is critical to ensure proper catalyst aging.
Exposure to excessive exhaust temperatures may potentially cause non-reversible thermal deactivation
of the catalyst coating, and such damage would not be representative of real world use. A complete
record of the air-fuel ratio (AFR), catalyst inlet and bed temperatures was recorded to allow analysis of
the thermal exposure. Histogram data are presented for API01 Malibu in Figures 4 and 5. Exhaust and
catalyst temperature histogram data are provided for all vehicles in the Appendix 11.4.
18.0
17.8
17.6
17.4
17.2
17.0
16.8
16.6
16.4
16.2
16.0
15.8
15.6
15.4
15.2
15.0
14.8
14.6
14.4
14.2
14.0
13.8
13.6
13.4
13.2
13.0
12.8
12.6
12.4
12.2
100
90
80
70
60
50
40
30
20
10
0
12.0
Hours at AFR
Distinct air-fuel ratios for each of the four modes of the CARB modified RAT-A cycle are apparent in the
AFR histogram (Figure 4). The data confirm the exhaust inlet temperature was held to 825°C for a
majority of the test cycle, as expected since Mode 1 is longest in duration (Figure 5, top). Temperature
was hottest near the front face of the close coupled catalyst, due to an exothermic reaction of the
exhaust gas. A peak temperature measurement of 1015°C was reached during the aging cycle.
AFR
Figure 4. Air-Fuel Ratio Histogram for Vehicle API01 over the 225 hour Aging Run
Page 14
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
100
CCC Front Bed
1050
1040
1030
1020
1010
990
1000
980
970
960
950
940
930
920
910
900
890
880
870
860
850
840
830
820
810
800
790
780
770
UBC Front Bed
760
90
80
70
60
50
40
30
20
10
0
CCC Inlet
750
Hours at Temperature
Temperature (°C)
Figure 5. Exhaust Inlet, Close Coupled Catalyst and Underbody Catalyst Temperature Histograms for
Vehicle API01 over the 225 hour Aging Run
Median and peak catalyst exposure temperatures are summarized in Table 7. Vehicle API03 and API05
(Sonata and A3, respectively) had the highest exposure temperatures. Vehicle API02 (Civic) had
significantly lower exothermic reaction at the CCC front bed location. The close coupled catalyst
temperature results for vehicle API06 (Camry) pertain to the left bank of the V6 engine.
Page 15
Table 7. Median and Peak Catalyst Exposure Temperatures over Aging Period (225 hours)
Vehicle
API01
API02
API03
API04
API05
API06
6.2
Make
Malibu
Civic
Sonata
Focus
A3
Camry
Close Coupled Catalyst
Underbody Catalyst
Front Bed Temperature (°C) Front Bed Temperature (°C)
Median
Peak
Median
Peak
Temperature Temperature Temperature Temperature
859
1015
791
850
853
955
NA
NA
891
1035
809
895
868
1025
809
895
891
1015
823
895
865
1005
788
870
Chassis Dynamometer Lab and Emissions Measurement
Emissions tests were performed in certification-compliant emissions laboratories at SGS Environmental
Testing Corporation in Aurora, Colorado (Figure 6). All tests were run on Site 2, featuring a Burke Porter
48” roll dynamometer in a temperature and humidity controlled environment. The laboratory has a
constant volume sampling system (CVS), raw modal and dilute bag gas sampling and analysis. The
emission sampling arrangement is shown in Figure 7.
Figure 6. API02 Civic in SGS-ETC Site 2 Chassis Dynamometer Emissions Lab
Page 16
Raw Tailpipe
Raw Intermediate Raw Engine Out
Under Body Cat
Close Coupled Cat
MSS
1st Dil
Bags
CVS Tunnel
2nd Dil
EEPS
CPC
PM2.5µm
cyclone
(heated)
PM Filter
(heated)
Figure 7. Emissions Sampling Arrangement
Vehicle API06 was equipped with a V6 engine. The continuous raw stream exhaust samples were drawn
from both banks at the engine-out and intermediate locations. The raw stream emissions presented in
this report therefore represent the combined emissions from both banks of the engine.
The following equipment was used to ensure accurate measurement of the very low emission
concentrations expected from these vehicles:

Bag samples were simultaneously collected from the diluted vehicle exhaust and from the
ambient, to ensure quantification of the background, and accurate calculation of cycle average
exhaust mass emissions. Bag gas analysis included measurement of CO, CO2, NOx, total HC, and
CH4.

NMHC was equal to the FID total hydrocarbons minus the response factor-corrected methane.
Methane measurement was by gas chromatograph FID.

Continuous raw tailpipe emissions were measured to provide information on the time to
catalyst light-off, and also to provide redundant information for bag-to-modal mass
comparisons. This bag-to-modal mass correlation served as a quality check for each test.

Continuous engine-out raw emissions were measured to provide information on catalyst
conversion efficiency. The test site used three raw sample streams to determine catalyst
conversion efficiency for close coupled and underbody catalysts.
Page 17

Low range analyzers and low concentration span gas bottles were used to ensure appropriate
analyzer response and resolution, per normal operating practice.

Fuel consumption was calculated using the carbon balance method, accounting for actual mass
% of carbon, hydrogen and oxygen in the fuel. Fuel economy was calculated using the
“uncorrected method”. The corrected calculation for MPG, per 40CFR600.113-08(h)(1), was not
applicable for oxygenated fuels used in the study.
Speciation of the exhaust gas for NMOG determination was beyond the scope of this study.
mass emissions were estimated using a formula from an experimental correlation [Ref. 15]:
NMOG
NMOGEST = (%EtOH * 0.0071 + 1.0302) * NMHC
where %EtOH was vol% ethanol in fuel. NMOG results presented in this report were estimated using
this formula. For gasoline containing 10%vol ethanol, NMOGEST = 1.1012 * NMHC.
The effect of sulfur on particulate matter and particle number emissions was of interest, especially with
the inclusion of GDI-equipped vehicles in the study. The entire exhaust volume was diluted in a full
dilution tunnel (Figure 7) for the purposes of particulate matter measurement.
The primary mass measurement for the study was made using an AVL483 photo acoustic microsoot
sensor (MSS). This instrument sampled from the CVS tunnel to minimize thermophoretic deposition
losses. The instrument only measures the soot fraction (elemental carbon fraction) of the total
particulate matter. The instrument is very sensitive, with a measurement resolution of ≤ 0.01 mg/m3.
Particulate matter (PM) samples were taken on Teflo 47mm filter media using a 40CFR Part 1065
compliant particulate matter sampler. Filters were processed in a temperature and humidity controlled
clean room equipped with electrostatic charge neutralizers and a Mettler Toledo UMX2 microbalance.
PM filter loading was commonly under 20µg for Phase 2 and Phase 3 of the FTP75 cycle, and not as
repeatable as the microsoot sensor instrument. PM measurements were made primarily to estimate of
the elemental carbon fraction of the total particulate matter. Particle Number (PN) measurements were
made using equipment compliant to the Euro 6 PMP GPRE specification. Diluted exhaust samples were
extracted from the CVS and coarse particles removed with a cyclone. The sample was further diluted
using a Matter Engineering rotating disk diluter, and then passed through a thermodenuder (300°C
evaporation tube) to remove nuclei mode volatile and sulfate aerosols. Second stage dilution was used
to prevent re-condensation. Particle number measurement was made using a TSI Model 3790
Condensation Particle Counter (CPC). The CPC has a 23nm D50 cutoff. Only accumulation mode solid
particles were counted.
Particle size distribution (PSD) was measured with a TSI Model 3090 Engine Exhaust Particle Sizer (EEPS)
spectrometer. The data was used primarily to verify the removal of nuclei mode particles. The EEPS
performs particle size classification based on differential electrical mobility classification. Charging of the
aerosol is accomplished through two unipolar diffusion chargers. The charged particles are collected on
electrically isolated electrodes located at the outer wall, and the PN concentration is determined by
measuring the electrical current collected. An inversion algorithm is used to de-convolute the data,
converting currents from the electrometers into 32 channels of output. This process allows the
maximum resolution of the instrument to be represented by output channels that are equally spaced on
a log scale between 5.6 nm and 560 nm. PN data was collected at a sampling rate of 1 Hz over the entire
Page 18
test cycle. The EEPS sampled from the same evaporation tube and diluter system used for the CPC. The
EEPS also produced total particle number counts, but the data is less reliable than the CPC in part due to
electrometer noise at low particle concentrations.
Statement on Testing at High Altitude
SGS Environmental Testing Corporation is located in Aurora, Colorado, at 5440 feet elevation above sea
level. SGS-ETC performs emissions certification tests for vehicle and engine manufacturers, at local
altitude and at other altitudes by employing altitude simulation equipment.
For this present study, the data analysis is focused on making relative comparison of vehicle emissions
when tested on fuels having different sulfur content. The relative trends from this study are expected
to be representative of results obtained at lower altitudes. Modern vehicles employ speed-density or
MAF-based engine control systems that have compensation for barometric pressure. Under closed
loop operation, fuel-air stoichiometry is controlled ensuring exhaust and catalyst temperatures are
comparable at different altitudes. Under hard acceleration open loop operation, vehicles employ long
term fuel trim (LTFT) adaptation for fuel enrichment and catalyst thermal protection. Because of these
control strategies, exhaust and catalyst temperatures are comparable at different altitudes. This point is
illustrated by comparing the catalyst bed temperatures for the 2009 Malibu. The same vehicle model
was tested at SGS-ETC (5440 feet) and in Auburn Hills, Michigan (960 feet) [Ref. 5]. Close coupled
catalyst front bed temperatures were in general agreement for the FTP75 and more aggressive US06
driving cycles (Figures 8 and 9, respectively). Exact thermocouple placement was not assured for this
comparison.
Figure 8. Catalyst Bed Temperatures for 2009 Malibu at 5440 feet and 960 feet Elevation – FTP75
Page 19
Figure 9. Catalyst Bed Temperatures for 2009 Malibu at 5440 feet and 960 feet Elevation – US06
6.3
Vehicle Preparation and As-Received Exhaust Emissions
Road load derivations were performed on the Burke Porter dynamometer per SAE J2264. The
equivalent test weights and road load coefficients used for the study are provided in Appendix 11.5.
The oil and oil filter were changed on each vehicle prior to the start of testing. Motor oils meeting
manufacturer recommended specifications were used (Appendix 11.6). The study required using the
same brand of motor oil for all vehicles. Since some oil viscosities were only available in a synthetic
formulation, Mobil 1 synthetic oil was used. Some of the motor oils were very light viscosity and had
the potential to impact hydrocarbon emissions measurement. To condition the oil following the oil
change, each vehicle was run for at least two consecutive Standard Road Cycles.
The vehicles were tested in the as-received condition, to establish emissions for the factory original
catalysts at low miles.
The starting vehicle mileage is provided in Table 5. Federal certification
gasoline (40CFR86.113-04) was used for these as-received emissions tests only, because the California
LEV III fuel was not available at the time of testing. The test sequence was:





Drain and 40% refill
Four LA4 prep cycles
Drain and 40% refill
12 to 24 hour soak
FTP75 3-bag emissions test, bag only
As-received vehicle emissions results are shown in Table 8. The vehicle emissions were compared to
the most stringent standard that applied for that vehicle model (California SULEV-II, except for API06
certified to Federal Tier 2 Bin 5). This comparison was made to verify the selected vehicles were
representative of properly operating vehicles in the fleet. NOx, CO and NMOG emissions were all below
Page 20
the applicable emissions standard. NMOG emissions were very near to the standard for vehicles
certified to SULEV-II. This trend may partly be explained because the “as-received” emissions tests
performed differed from the certification procedure:



Federal Tier 2 certification gasoline was used, rather than oxygenated California Phase 2 fuel.
Oxygenated gasoline has been shown to lower NMHC and CO for some late model vehicles [Ref.
16, 17]
No canister load was performed
NMOG emissions were estimated from NMHC, per Section 6.2
NMHC and estimated NMOG emissions were very close in value and appear indistinguishable in Table 8
because Federal Tier 2 certification gasoline contains no oxygenate.
Table 8. As-Received Vehicle Exhaust Emissions, FTP75, Federal Certification Gasoline
NOx
API01 - 2009 Malibu
SULEV II Standard @ 150k miles
API02- 2012 Civic
API03 - 2012 Sonata
API04 - 2012 Focus
API05 - 2012 A3
API06 - 2012 Camry
T2 B5 Standard @ 50k miles
0.008
0.020
0.006
0.020
0.007
0.020
0.009
0.020
0.011
0.020
0.021
0.050
FTP75 Weighted Bag Emissions (g/mile)
CH4
CO
HC
NMHC Est NMOG
0.678
1.000
0.141
1.000
0.206
1.000
0.037
1.000
0.318
1.000
0.093
3.400
0.012
-0.010
-0.008
-0.008
-0.012
-0.012
--
0.004
-0.002
-0.001
-0.001
-0.005
-0.002
--
0.009
-0.008
-0.007
-0.007
-0.008
-0.010
--
0.009
0.010
0.008
0.010
0.007
0.010
0.007
0.010
0.008
0.010
0.010
0.075
MPG
24.32
-34.52
-26.64
-31.62
-27.51
-25.6
--
The factory original exhaust system was then removed for each vehicle and replaced with the catalyst
and sensor components that were aged on the engine stand (Section 6.1). Additional instrumentation
was added to measure exhaust gas temperatures, and to allow for raw exhaust gas sample extraction
for emissions measurement. Typical instrumentation used for the vehicle test is shown in Figure 10.
Figure 10. Typical Exhaust System Instrumentation for Vehicle Emissions Tests
Page 21
7.0 Sulfur Reversibility Study – Individual Vehicle Test Results
Exhaust emissions and fuel economy results are shown for individual vehicles in Figures 11 to 16. These
charts display the results weighted over the three phases for the FTP75 emissions test cycle. Gaseous
emissions were determined from bag analysis. Soot and particle number emissions were measured by
drawing continuous samples from the primary dilution tunnel.
There were ten data points for each reversibility sequence run: four baseline tests run on 10 ppm sulfur
fuel, three tests using 80 ppm fuel, and three tests after the vehicle was switched back to 10 ppm fuel
(Section 3). These ten test results are shown sequentially in the Figures 11 to 16, from left to right. For
each of these three segments of data, the mean value is shown as a horizontal line. The vertical scales
for these charts were chosen to magnify the results to identify small changes in emissions, in favor over
keeping the scales the same for all vehicles. In this section, observations are made regarding emissions
trends before, during and after the 80 ppm fuel exposure. Owing to the considerable variability within
each group of data, some of the observed trends discussed in this section may not be statistically
significant. A statistical analysis of the reversibility effects was performed using the FTP75 weighted
data in Section 8, to draw conclusions about individual vehicles and the test fleet of six vehicles.
Gaseous mass emissions were also determined using continuous raw exhaust stream measurements
taken at the engine-out, between catalyst, and tailpipe locations. This data was used to quantify the
conversion efficiencies of the close coupled and underbody catalysts. The raw exhaust emissions and
catalyst efficiency data were of secondary interest for this study, but the interested reader may gain
some important insights regarding catalyst light-off, catalyst system behavior, and sources of emissions
variability (Sections 7.7 and 7.8, Appendix 11.7 and 11.8).
A representative report of soot, particle number and particle size distribution is provided for each of the
vehicles run on 10 ppm and 80 ppm sulfur fuels in Appendix 11.9. The same color contour scale was
used for all color contour plots presented, to allow visual comparison. There is currently no certification
standard for automotive particle number emissions in the United States. The Euro 6 PN standard of
6.0x1011 #/km (9.7x1011 #/mile), which begins for some GDI vehicle weight classes in September 2014,
provides some perspective on future PN emissions levels. It is noted that Euro 6 PN standard applies to
the NEDC cycle. Therefore a strict comparison of these results to the Euro 6 standard is not appropriate
because the NEDC is a geometric based cycle with fewer transient maneuvers than the FTP75.
Page 22
7.1
API01 2009 Chevrolet Malibu
Emissions results for the 2009 Malibu fitted with aged catalysts and sensors are shown in Figure 11.
NMOG and NOx emissions appeared to increase with each subsequent emissions test run on 80ppm
sulfur fuel. For the third test run on 80ppm fuel, NMOG and NOx emissions exceeded the SULEV-II
emissions standards of 0.01 and 0.02 g/mile, respectively. Following the change back to 10 ppm sulfur
fuel, mean NMOG emissions were just below the baseline mean value indicating the sulfur effects on
NMOG were reversible. NOx emissions dropped more gradually during the subsequent recovery tests
performed following the switch to 10 ppm fuel, with the final test result having NOx emissions below
the baseline NOx levels.
NOx emissions more than doubled when this vehicle was run on 80 ppm fuel, relative to the baseline.
NOx emissions from this vehicle responded to fuel sulfur changes differently than other vehicles in the
study.
There was no observed change in mean CO emissions during and after 80 ppm sulfur fuel exposure.
Soot mass and PN emissions showed increases during and after the 80 ppm fuel exposure, but the
emissions were at very low levels for this SFI-equipped vehicle. The variability of the soot and PN data
was considered in Section 8 to conclude that the differences in the means before and after 80ppm fuel
exposure were not statistically significant.
The first baseline test point showed higher CO and soot emissions than all other tests. The test met
quality assurance criteria and the result remained in the dataset for statistical analysis. No soot
measurement was available for the third test using 80 ppm sulfur fuel due to instrument malfunction.
The soot fraction of total PM was estimated to be 56% for the reversibility sequence performed. The
highest PM measurement for the vehicle was 1.1 mg/mile (corresponding to the first baseline test in
Figure 11), far below the 10 mg/mile emissions standard.
The 2009 Malibu was chosen for this study to allow a comparison with previous published results [Ref.
5]. A comparison of the catalyst conversion efficiency, raw tailpipe emissions, and discussion is provided
in Section 7.9.
Page 23
API01
NMOG
grams/mile
0.012
0.01
0.008
0.006
NOx
grams/mile
0.02
0.01
0
CO
grams/mile
0.8
0.6
0.4
0.2
Miles per Gallon
0
Fuel Economy
26
25.5
25
24.5
24
Soot
mg/mile
0.6
0.5
0.4
0.3
0.2
Particle Number
#/mile
1.5E+12
1.0E+12
5.0E+11
Test Sequence
10ppm Baseline
80ppm
10ppm Reversibility
Average
Figure 11. Sulfur Reversibility Test Results, API01 Malibu
Page 24
7.2
API02 2012 Honda Civic EX
Emissions results for the 2012 Civic fitted with aged catalysts and sensors are shown in Figure 12. All
weighted NMOG emission results exceeded the SULEV-II emissions standard of 0.01 g/mile for the
vehicle equipped with the aged catalyst, using both 10 ppm and 80 ppm sulfur fuels. NMOG emissions
for some tests approached 0.02 g/mile, nearly double the standard. NOx and CO emissions were under
the SULEV-II standards.
The mean NMOG, CO and NOx emissions all increased for 80 ppm fuel tests, compared to the baseline
emissions performed using 10 ppm fuel. Following the change back to 10 ppm sulfur fuel, mean NMOG,
NOx and CO emissions were just below the baseline mean value indicating the sulfur effects on
emissions were reversible.
The highest PM measurement for the vehicle was 1.3 mg/mile, far below the 10 mg/mile emissions
standard. The soot fraction of total PM was estimated to be 45% for the reversibility sequence
performed. Soot mass and PN emissions were at very low levels for this SFI-equipped vehicle. There
were only very slight changes to mean soot and PN emissions during and after 80 ppm sulfur fuel
exposure.
Page 25
API02
grams/mile
0.025
NMOG
0.02
0.015
0.01
NOx
grams/mile
0.02
0.01
grams/mile
0
0.3
CO
0.2
0.1
Miles per Gallon
0
Fuel Economy
35
34.5
34
33.5
33
Soot
mg/mile
0.5
0.4
0.3
0.2
0.1
0
Particle Number
#/mile
1.5E+12
1.0E+12
5.0E+11
0.0E+00
Test Sequence
10ppm Baseline
80ppm
10ppm Reversibility
Average
Figure 12. Sulfur Reversibility Test Results, API02 Civic
Page 26
7.3
API03 2012 Hyundai Sonata
Emissions results for the 2012 Sonata fitted with aged catalysts and sensors are shown in Figure 13.
Most weighted NMOG emission results exceeded the SULEV-II emissions standard of 0.01 g/mile, when
the vehicle was run on 10 ppm and 80 ppm fuels using the aged catalyst. NMOG emissions appeared to
increase with each subsequent emissions test run on 80ppm sulfur fuel, peaking at 0.020 g/mile for the
third test. The NMOG emissions had high “within group” variability, meaning the variability was quite
large for consecutive tests performed on the same fuel. The variability in NMOG emissions is attributed
to catalyst performance. Engine-out emissions were relatively constant for consecutive tests by
comparison (Appendix 11.8), and had a considerably lower coefficient of variation than post-catalyst
emissions as further discussed in Section 7.8. The variation in catalyst performance does not appear due
to thermal differences, since engine exhaust and catalyst temperature profiles were very repeatable for
the tests run (Appendix 11.7).
All NOx and CO emissions results were well under the SULEV-II standards. Combined NMOG+NOx
emissions were under the proposed Tier 3 Bin 30 standard of 0.03 g/mile for both 10ppm and 80ppm
sulfur fuels.
The mean NMOG, CO and NOx emissions all increased for 80 ppm fuel tests, compared to the baseline
emissions performed using 10 ppm fuel. Following the change back to 10 ppm sulfur fuel, mean NMOG,
NOx and CO emissions decreased relative to the 80 ppm fuel results, but remained slightly higher than
the baseline results run with 10 ppm fuel. The variability of the data has a bearing on determining if the
mean values before and after 80 ppm fuel exposure are statistically equivalent, and is discussed in
Section 8.
Vehicle API03 was equipped with a GDI engine. This vehicle produced the highest PM, soot and particle
number emissions compared to other vehicles in the study. Nevertheless, PM emissions were below
SULEV-II mass standards. The highest PM measurement for the vehicle was 6.3 mg/mile, below the 10
mg/mile emissions standard. The soot fraction of total PM was estimated to be 71% for the reversibility
sequence performed.
Soot and particle number emissions were highest during the first hill in Phase 1 of the FTP75, but
emissions were also evident during transient maneuvers even after the catalyst warm-up (Appendix
11.9).
This vehicle’s PM, soot and PN emissions were all found to be sensitive to 80 ppm fuel. Mean soot and
PN emissions increased by 11% and 17% respectively when using 80 ppm fuel, relative to the baseline
results. Following the change back to 10 ppm sulfur fuel, mean soot and PN emissions were just below
the baseline mean value indicating the sulfur effects on emissions were reversible.
Page 27
API03
0.025
NMOG
grams/mile
0.02
0.015
0.01
0.005
NOx
grams/mile
0.015
0.01
0.005
grams/mile
0
0.3
CO
0.2
0.1
Miles per Gallon
0
Fuel Economy
28
27.5
27
26.5
mg/mile
26
4.5
Soot
4.0
3.5
3.0
Particle Number
#/mile
7.0E+12
6.0E+12
5.0E+12
4.0E+12
Test Sequence
10ppm Baseline
80ppm
10ppm Reversibility
Average
Figure 13. Sulfur Reversibility Test Results, API03 Sonata
Page 28
7.4
API04 2012 Ford Focus
Emissions results for the 2012 Focus fitted with aged catalysts and sensors are shown in Figure 14.
There are two complete reversibility test sequences shown on each chart. The left set designated as
the “Initial Sequence” is discussed first.
Initial Sequence
NMOG and CO emissions were found to be sensitive to the 80 ppm fuel. When run on 80 ppm fuel, the
vehicle produced mean NMOG and CO emissions that were 16% and 77% higher, respectively, compared
to results using the 10 ppm baseline fuel. The coefficient of variation for NMOG and CO emissions were
quite large compared to engine-out emissions, and compared to tailpipe emissions from other vehicles
in the study (Section 7.8). This emissions variability was isolated to the catalyst performance, as it
occurred despite the relatively constant engine-out emissions (Appendix 11.8), and comparable catalyst
temperature profiles for the tests run (Appendix 11.7).
The vehicle’s mean NMOG and CO emissions both showed good reversibility when the vehicle was
switched back to 10 ppm sulfur fuel, following the 80 ppm fuel exposure. For the Initial Sequence, mean
NOx emissions did not change appreciably during or after the 80 ppm fuel exposure.
This vehicle was equipped with a GDI engine. PM, soot and PN emissions were higher than those
measured from the SFI-equipped vehicles in the study as expected. The highest PM measurement for
the vehicle was 2.6 mg/mile, well below the 10 mg/mile PM emissions standard. The soot fraction of
total PM was estimated to be 62% for the reversibility sequence performed. Soot and particle number
emissions peaked in Phase 1 of the FTP75, but emission peaks were also evident during accelerations
even after the catalyst warm-up (Appendix 11.9).
The mean values for soot and PN emissions increased during testing with 80 ppm sulfur fuel, and
remained at that elevated level following the switchback to 10 ppm fuel. After deeper examination of
the data, this behavior was not believed to be a fuel sulfur effect but rather was due to poor
repeatability in this vehicle’s soot and PN emissions (Section 8.2).
Repeat Sequence
The entire reversibility test sequence was repeated for vehicle API04, in order to further investigate the
sensitivity and reversibility of soot and PN emissions to fuel sulfur. The dataset located at right in Figure
14 is designated the “Repeat Sequence” and further discussed here.
Upon retest, very different observations were made regarding the sensitivity of vehicle soot and PN
emissions to fuel sulfur. In the retest, there was no statistical difference in the means at the baseline, 80
ppm fuel exposure, and 10 ppm fuel recovery segments of the test sequence. The variation of the soot
and PN data is further discussed in Section 8.2.
NMOG emissions were just over the SULEV-II standards for two of the emissions tests, whereas NOx and
CO emissions were well within the standards. Combined NMOG+NOx emissions were under the
proposed Tier 3 Bin 30 standard of 0.03 g/mile for both 10ppm and 80ppm sulfur fuels. Following the
change back to 10 ppm sulfur fuel, mean NMOG, NOx and CO emissions were just below the baseline
mean values indicating the sulfur effects on emissions were reversible.
Regarding the statistical
analysis of gaseous emissions, the conclusions drawn from the Initial Sequence and Repeat Sequence
were identical (Section 8.2).
Page 29
API04
0.015
NMOG
grams/mile
Initial Sequence
0.01
grams/mile
0.005
0.015
NOx
0.01
0.005
0
CO
grams/mile
0.3
0.2
0.1
Miles per Gallon
0
Fuel Economy
33.5
33
32.5
32
mg/mile
31.5
1.5
Soot
1
0.5
0
4.0E+12
#/mile
Repeat Sequence
Particle Number
3.0E+12
2.0E+12
Test Sequence
10ppm Baseline
80ppm
10ppm Reversibility
Average
Figure 14. Sulfur Reversibility Test Results, API04 Focus
Page 30
7.5
API05 2012 Audi A3
Emissions results for the 2012 Audi A3 fitted with aged catalysts and sensors are shown in Figure 15.
NMOG emission results were near or just above the SULEV-II emissions standard of 0.01 g/mile for the
vehicle equipped with the aged catalyst, using both 10 ppm and 80 ppm sulfur fuels. NOx emissions
from a single test (the third test run on 80 ppm fuel) were over the emissions standard of 0.02 g/mile.
All other NOx and CO emissions results were within the SULEV-II standards.
This vehicle was equipped with a turbocharged GDI engine. NMOG, CO, Soot and PN emissions were not
sensitive to the change to 80 ppm sulfur fuel, so reversibility of vehicle emissions was not relevant for
those species.
NOx emissions increased significantly for a single test run on 80 ppm fuel. Following the change back to
10 ppm sulfur fuel, mean NOx emissions were the same as the baseline mean values indicating the
sulfur effects on NOx emissions were reversible.
The highest PM measurement for the vehicle was 2.8 mg/mile, well below the 10 mg/mile emissions
performed.
Page 31
API05
grams/mile
0.015
NMOG
0.01
grams/mile
0.005
0.04
NOx
0.03
0.02
0.01
grams/mile
0
0.8
CO
0.6
0.4
0.2
Miles per Gallon
0
Fuel Economy
28
27.5
27
26.5
mg/mile
26
1.5
Soot
1
0.5
#/mile
5.0E+12
0
Particle Number
4.0E+12
3.0E+12
2.0E+12
Test Sequence
10ppm Baseline
80ppm
10ppm Reversibility
Average
Figure 15. Sulfur Reversibility Test Results, API05 A3
Page 32
7.6
API06 2012 Toyota Camry
Emissions results for the 2012 Camry fitted with aged catalysts and sensors are shown in Figure 12.
NMOG, NOx and CO emissions were far under the Federal Tier 2 Bin 5 standards that apply to this
vehicle, for all fuels tested. The Camry emissions test results were more repeatable than other vehicles
in the study.
NMOG, NOx and CO emissions test results peaked for the first emissions test performed following 300
miles of conditioning on the chassis dynamometer using 80 ppm fuel. The US06 cycle run between
emissions tests appeared to effectively reduce the sulfur effects on gaseous emissions for subsequent
tests using 80 ppm fuel. The emissions from this vehicle therefore appeared to have some sensitivity to
the 80ppm fuel, but it is postulated that the effects may not be as apparent for aggressive driving
applications.
Following the change back to 10 ppm sulfur fuel, mean NMOG, NOx and CO emissions were at or just
below the baseline mean value indicating the sulfur effects on emissions were reversible.
The highest PM measurement for the vehicle was 0.6 mg/mile, far below the 10 mg/mile emissions
performed.
This SFI-equipped vehicle has the lowest PM, soot and PN emissions of all vehicles in the study. The
change to mean soot and PN emissions was negligible during and after 80 ppm sulfur fuel exposure.
Page 33
API06
NMOG
grams/mile
0.04
0.03
0.02
0.01
0
NOx
grams/mile
0.03
0.02
0.01
grams/mile
0
0.8
CO
0.6
0.4
0.2
Miles per Gallon
0
Fuel Economy
27.5
27
26.5
26
25.5
Soot
mg/mile
0.5
0.4
0.3
0.2
0.1
0
Particle Number
#/mile
1.5E+12
1.0E+12
5.0E+11
0.0E+00
Test Sequence
10ppm Baseline
80ppm
10ppm Reversibility
Average
Figure 16. Sulfur Reversibility Test Results, API06 Camry
Page 34
7.7
Comparison of Vehicle Exhaust Temperatures and Emissions
A key aspect of the study was to ensure a proper sulfur purge occurred to condition the catalysts at the
start of the reversibility test sequence. The EPEFE cycle [Ref. 7] was used to accomplish the catalyst
sulfur purge. The EPEFE cycle included a series of ten wide open throttle accelerations to increase
catalyst operating temperature. During WOT acceleration, most vehicles use open loop fueling control
to command rich combustion for catalyst thermal protection. A segment of the EPEFE cycle shown in
Figure 17 illustrates the fuel enrichment, exhaust gas temperature and catalyst front bed temperature
during the WOT event.
Figure 17. Segment of the EPEFE Cycle Used for Catalyst Sulfur Purge
Typical peak operating temperatures for the WOT event are compared for the vehicles in Table 9. The
exhaust gas temperature exceeded the criteria of 700°C for all vehicles without resorting to artificial
means such as increasing the dyno roll load. The temperatures for vehicle API01 were substantially
hotter than the other vehicles. For vehicle API06, the close coupled catalyst temperatures in the
following tables correspond to the left bank of the V6 engine.
Table 9. Typical Exhaust Gas and Catalyst Bed Temperatures for EPEFE Cycle WOT Events
Typical WOT Conditions
CC Catalyst Inlet Temp (°C)
CC Catalyst Front Bed Temp (°C)
UB Catalyst Front Bed Temp (°C)
Lambda
API01
854
888
771
0.76
API02
788
838
-0.87
API03
782
843
766
0.77
API04
788
838
777
0.83
API05
754
810
760
0.82
API06
777
849
721
0.88
Criteria
>700
< 1.0
The reversibility test sequence used in this study included alternating US06 and FTP75 cycles, to
encompass both higher speed and lower speed vehicle operation (Section 3). The US06 cycle has higher
exhaust temperatures than the FTP75, and therefore may play a role in reversing the catalyst sulfur
poisoning effect depending on the vehicle technology. A comparison of US06 and FTP75 median and
Page 35
peak catalyst temperatures is provided in Table 10. This table illustrates a balance in vehicle operation
over the reversibility test sequence. For about 75% of the time the vehicle was operated on the longer
duration FTP75 cycle with speed averaging 21.2 mph. For the remaining 25% of time, the vehicle was
operated over the US06 cycle averaging 48.4 mph, and the median CCC front bed temperature increased
by about 140 to 180°C relative to the FTP75 depending on the vehicle technology.
Table 10. Median and Peak Catalyst Temperatures for the US06 and FTP75 Cycles, 10ppm Sulfur Fuel
US06 Cycle, Median and Peak Temperatures (US06 Duration=596 seconds, Average Speed=48.4 mph)
Engine Out
Temperature (°C)
Vehicle
API01
API02
API03
API04
API05
API06
Model
Malibu
Civic
Sonata
Focus
A3
Camry
Underbody Catalyst
Median
Peak
Median
Peak
Median
Peak
Test ID Temperature Temperature Temperature Temperature Temperature Temperature
2110425
724
846
809
944
695
795
2109139
603
757
735
859
--2110626
695
839
804
932
697
806
2110386
650
903
804
906
716
809
2110205
598
714
700
791
649
743
2110109
603
699
721
847
556
633
FTP75 Cycle, Median and Peak Temperatures (FTP75 Duration=1877 seconds, Average Speed=21.2 mph)
Engine Out
Temperature (°C)
Vehicle
API01
API02
API03
API04
API05
API06
Model
Malibu
Civic
Sonata
Focus
A3
Camry
Underbody Catalyst
Median
Peak
Median
Peak
Median
Peak
Test ID Temperature Temperature Temperature Temperature Temperature Temperature
2110445
569
713
654
845
506
610
2109547
456
632
565
744
--2110637
556
702
651
834
513
627
2110397
469
601
621
752
492
610
2110229
463
558
552
711
496
570
2109627
457
587
579
726
378
456
A comparison of catalyst warm-up temperatures and catalyst light off is shown for the first phase of the
FTP75 test in Figure 18. Vehicle API03 had the fastest warm-up of engine-out exhaust gas. The
manufacturer claims to use a late fuel injection strategy to promote fast catalyst light off and this does
appear to be the case as tailpipe NOx emissions were very low for this vehicle in comparison to other
vehicles (Figure 18, bottom).
Vehicle API01 had the fastest warm-up of the catalyst front bed temperature. This vehicle was
equipped with secondary air injection and employed rich operation at startup to promote fast catalyst
light-off [Ref. 5].
Catalyst warm-up and tailpipe NOx emissions are shown for individual vehicles in Appendix 11.7.
Representative data is shown for a baseline test on 10 ppm fuel, for an 80 ppm fuel test, and for a
reversibility test returning to 10 ppm fuel. The catalyst temperatures were very repeatable for FTP75
tests regardless of fuel, suggesting that the differences in NOx emissions were not due to differences in
substrate warm-up during testing.
Page 36
1000
Temperature (°C)
800
Engine Out Temp
600
400
200
API01
API02
API03
API05
API06 Bank 1
API06 Bank 2
API04
0
1000
CC Catalyst Bed Temp
Temperature (°C)
800
600
400
200
API01
API02
API03
API04
API05
API06 Bank 1
API06 Bank 2
0
1000
Temperature (°C)
UB Catalyst Bed Temp
800
600
API01
API03
API05
API06
API04
400
200
0
800
Tailpipe NOx Concentration
Tailpipe NOx (ppm)
700
600
500
400
300
200
API01
API02
API03
API04
API05
API06
100
0
0
20
40
60
Test Time (sec)
80
100
120
Figure 18. Catalyst Warm-Up and NOx Light Off Comparison, 10ppm Sulfur Fuel
Page 37
Soot emissions are compared for the six vehicles tested using 10 ppm and 80ppm fuels in Figure 19. The
soot concentrations were from measurements taken in the CVS dilution tunnel, with the same CVS flow
used for all tests. Therefore, soot concentrations also represents continuous soot mass emissions, but
are not to be compared with raw stream concentrations. All of the GDI-equipped vehicles emitted soot
during the start-up and before the vehicle was shifted into drive (between 0 and 20 seconds). All
vehicles produced measurable soot during the first acceleration. Vehicle API03 produced by far the
highest soot emissions. Soot emissions decreased substantially upon vehicle warm-up.
Only vehicle API03 was conclusively found to have higher mean soot and particle number emissions on
80 ppm fuel compared to 10 ppm fuel. Vehicles equipped with GDI engines had about five to seven
times higher soot mass and particle number emissions on average compared to the SFI-equipped
vehicles.
A strong correlation existed between soot mass and PN emissions, as expected since both methods
measured elemental carbon and excluded volatile organic and sulfate aerosols. Representative PN
emissions and size distributions are reported for 10 ppm and 80 ppm fuels in Appendix 11.9. It is noted
the same color contour scale was used for all color contour plots presented.
Figure 19. Soot Emissions Comparison in CVS Diluted Exhaust Stream, 10 and 80 ppm Sulfur Fuels
Page 38
7.8
Raw Emissions and Catalyst Efficiency Data
Raw exhaust stream measurements were taken at the engine-out, between catalyst, and tailpipe
locations. This data was used to quantify the conversion efficiencies of the close coupled and
underbody catalysts (Appendix 11.8). The raw exhaust emissions and catalyst efficiency data are of
secondary interest for this study, but some observations regarding catalyst system behavior and sources
of emissions variability are discussed in this section.
Conversion efficiency of hydrocarbon emissions was greater than 98% across the close coupled catalyst
for all vehicles in the study. For all vehicles except API05, all of the hydrocarbon conversion occurred
across the close coupled catalyst which is engineered for fast light-off, whereas comparatively little
hydrocarbon conversion occurred across the underbody catalyst. Vehicle API05 was the only vehicle to
have HC conversion across the underbody catalyst (Figure 20). The bars in the chart represent triplicate
test results for the three segments of the reversibility test sequence: baseline tests using 10 ppm sulfur
fuel, using 80 ppm fuel, and tests following the switch back to 10 ppm fuel.
Figure 20. Conversion of Hydrocarbons Across Close Coupled and Underbody Catalysts, Vehicle API05
The performance of close coupled catalysts and underbody catalysts varied substantially for different
vehicles, reflecting the diversity of the vehicle technology chosen for study. Vehicle API03 had very
repeatable engine-out emissions for the reversibility sequence, using both 10 ppm and 80 ppm fuels.
The performance of the close coupled catalyst was found to be affected by the 80 ppm fuel and had
lower NOx conversion efficiency (Figure 21, upper right).
The NOx concentration entering the
underbody catalyst was therefore higher for the 80 ppm fuel tests. But in contrast, the underbody
catalyst NOx conversion efficiency was better for the tests with 80 ppm sulfur fuel. Underbody catalyst
conversion efficiency improved for tests with higher inlet NOx concentrations (Figure 21, lower).
Vehicle API03 appeared to have interdependency between the exhaust feed gas concentration and
conversion efficiency, noting that catalyst temperatures were about the same for the tests (Appendix
Page 39
11.7). API04 exhibited similar behavior for some tests. These examples reinforce the importance of
testing the complete vehicle system to evaluate sulfur reversibility effects, because misleading
conclusions could be drawn from individual component results.
Figure 21. NOx Conversion Across Close Coupled and Underbody Catalysts, Vehicle API03
Some of the vehicles had quite substantial variations in gaseous emissions from bag analysis, as noted in
Sections 7.1 to 7.6. There are many possible contributors to these variations, but principle contributors
may be driver variation, measurement error at low emissions levels, engine variation and catalyst
performance variation. A quality plan was implemented to control test-related variations: for instance,
all tests were performed in the same chassis dynamometer laboratory and the same driver was used for
all except two of the tests. Moreover, all tests presented in this report met quality control criteria for
driver violations. There was evidence the variations seen in the emissions data were due to the vehicle
itself, since procedural controls and quality checks were used to minimize laboratory sources of
variation.
The raw emissions dataset was used to further explore the source of vehicle emissions variation. Mean
values and standard deviations for engine-out, intermediate, and tailpipe emissions were tabulated for
tests using 10 ppm sulfur fuel (7 total tests per vehicle). The coefficient of variation (COV=standard
deviation/mean) were compared at these three locations in Table 11. The COVs for NOx, CO and HC
were considerably smaller at the engine-out location for every vehicle in the study, relative to postcatalyst locations. This finding indicated the engine-out emissions were more repeatable (also shown in
Appendix 11.8), suggesting the vehicle was being driven consistently on the dyno from test-to-test.
Exhaust and catalyst temperatures, which are known to effect catalyst performance, were also very
repeatable from test-to-test (Appendix 11.7). COVs were 3 to 17 times higher at the tailpipe location
Page 40
compared to engine-out, indicating the catalyst system was a large source of variability in the emissions
data. Apparently, small variations in catalyst input parameters produced a large variation in tailpipe
emissions results. The tailpipe emissions COVs for vehicles API01 and API03 were large in comparison to
vehicles API05 and API06, suggesting the variability was a function of vehicle technology and was not
dominated by measurement error.
Table 11. Coefficient of Variation for Raw Exhaust Emissions, FTP75, 10 ppm Sulfur Fuel
Vehicle ID
NOx Emissions
API01
API02
API03
API04
API05
API06
CO Emissions
API01
API02
API03
API04
API05
API06
HC Emissions
API01
API02
API03
API04
API05
API06
7.9
Mean
3.38
2.73
2.55
2.38
2.58
2.89
Mean
10.83
6.11
11.79
11.19
10.85
11.91
Mean
1.19
1.51
1.74
2.03
1.71
1.94
Engine-Out
Stdev
0.14
0.09
0.06
0.08
0.03
0.04
Stdev
0.31
0.08
0.24
0.38
0.24
0.18
Stdev
0.03
0.03
0.06
0.08
0.04
0.04
COV
0.040
0.033
0.024
0.033
0.010
0.014
COV
0.028
0.013
0.020
0.034
0.022
0.015
COV
0.027
0.023
0.033
0.041
0.023
0.021
Mean
0.055
-0.016
0.022
0.087
0.026
Mean
0.871
-0.695
0.357
3.054
0.426
Mean
0.010
-0.010
0.010
0.017
0.019
Intermediate
Stdev
0.006
-0.004
0.005
0.019
0.003
Stdev
0.236
-0.054
0.032
0.239
0.050
Stdev
0.002
-0.003
0.002
0.020
0.001
COV
0.112
-0.264
0.248
0.217
0.119
COV
0.271
-0.078
0.089
0.078
0.117
COV
0.221
-0.298
0.225
0.018
0.079
Mean
0.0071
0.0074
0.0059
0.0065
0.0139
0.0213
Mean
0.3974
0.1255
0.1589
0.1137
0.4076
0.2838
Mean
0.0119
0.0190
0.0150
0.0104
0.0151
0.0267
Tailpipe
Stdev
0.0025
0.0011
0.0007
0.0009
0.0019
0.0023
Stdev
0.1953
0.0248
0.0320
0.0179
0.0336
0.0305
Stdev
0.0011
0.0032
0.0043
0.0014
0.0014
0.0016
COV
0.353
0.143
0.121
0.138
0.140
0.110
COV
0.491
0.198
0.201
0.157
0.082
0.107
COV
0.095
0.169
0.287
0.137
0.095
0.059
Comparison of API01 Malibu NOx Results with the Umicore Study
The 2009 Malibu SULEV-II PZEV was chosen for study in order to compare data with published results
from Umicore [Ref. 5]. The Umicore study reported NOx emissions results for the underbody catalyst
only.
The studies used the same specification vehicle, both equipped with dynamometer-aged aftertreatment
systems. A comparison of catalyst aging and test fuels is shown in Table 12. The Umicore study used 33
and 3 ppm sulfur fuels, whereas the present study used 80 ppm and 10 ppm sulfur fuels to explore
sulfur reversibility. Raw emissions measurements were made to determine catalyst conversion
efficiency.
Page 41
Table 12. 2009 Malibu SULEV-II PZEV Fuel Sulfur Studies – Catalyst Aging and Test Fuels
Umicore Study
API Sulfur Effects Reversibility Study
Close Coupled
Catalyst Aging
Catalyst aged on dyno to 150,000 mile equivalent
4-mode aging cycle for 150 hours
Peak bed temperature = 1030°C
Catalyst aged on dyno to 120,000 to 150,000 mile equivalent
Underbody
Catalyst Aging
CC and UB catalysts aged for different durations
CC and UB catalyst aged in same set-up
Aging Fuel
Not specified
Alcohol-free gasoline with 91 antiknock index
Fuel sulfur content = 18.5 to 43 ppm
CARB Phase II Certification Gasoline
Emissions Test Fuel 11% vol MTBE nominal
High Sulfur
Fuel sulfur content = 33 ppm
California LEV III Certification Gasoline
10% vol ethanol nominal
Fuel sulfur content = 80 ppm (by doping base fuel)
EEE-Lube Certification Gasoline
Emissions Test Fuel Alcohol free
Low Sulfur
California LEV III Certification Gasoline
10% vol Ethanol nominal
There were some differences in the test protocol that may be identified through the review of Section 3
and [Ref. 5]. In both studies, triplicate FTP75 emissions tests were performed using a “high sulfur” fuel,
and then triplicate tests were repeated following switchover to a “low sulfur” fuel. The NOx results
from the studies are compared in Figure 22, with Umicore results on top and results from the present
study on bottom.
Figure 22. 2009 Malibu NOx Emissions – Comparison between Umicore and API Fuel Sulfur Studies
The NOx emissions upstream of the underbody catalyst ranged from 25 to 48 mg/mile for the Umicore
tests, and 46 to 63 mg/mile for the present study. The close coupled and underbody catalyst
temperatures were comparable between the labs for the FTP75 emissions test and also for the US06
prep cycle that was run between emissions tests (Figures 8,9). The US06 cycle was not run between
emissions tests when the 3 ppm fuel was run at Umicore (Figure 22b).
Page 42
The Umicore results show lower catalyst conversion efficiency and higher tailpipe NOx emissions for
both 33 ppm and 3 ppm sulfur fuels, compared to 10 ppm fuel results from the present study. Baseline
NOx emissions (Figure 22c), and stabilized results from tests run after the 80 ppm fuel exposure (Figure
22d) were below the stabilized NOx emissions measured at Umicore using 3 ppm fuel (Figure 22b).
Tests were run to investigate the sensitivity of the underbody catalyst to fuel sulfur ranging from 10 to
30 ppm. Stabilized emissions results, run in a randomized order, are shown in Figure 23.
The
comparison of NOx using 30 ppm fuel (Figure 23) to the stabilized NOx results using 33 ppm fuel from
Umicore (Figure 22a Test 3) is favorable.
Figure 23. Sensitivity of API01 Underbody Catalyst NOx Conversion to Fuel Sulfur
The lowest underbody catalyst conversion efficiency was 73% from the present study, and occurred for
the first test run using 80 ppm fuel (Appendix 11.8). By contrast, NOx conversion efficiency ranged from
42 to 56% for four of the six Umicore tests run using 33 and 3 ppm sulfur fuels (Figure 22). The
“unstabilized” NOx emissions of 26 mg/mile (Figure 22a, Test 1) were considerably higher than NOx
emissions measured using 80 ppm fuel in the present study. The reason for these discrepancies may be
related to procedural differences leading up to the emissions tests, fuel differences, or catalyst aging
differences noted in Table 12.
7.10 Reversibility Data Tables
The emissions and fuel economy data from the sulfur reversibility study are provided in Tables 13 to 16.
The gaseous emissions were from bag analysis, and all results are weighted emissions over the FTP75
cycle. This dataset was used for the statistical analysis in Section 8.0.
Page 43
Table 13. Fuel Sulfur Reversibility Study Dataset for Analysis, API01 and API02
WTD
Bag
CH4
GPM
WTD
Bag
NMHC
GPM
WTD
Bag
NMOG
GPM
WTD
Bag
NOx
GPM
WTD
Bag
NMOG
+NOx
GPM
WTD
Bag
CO
GPM
WTD
Bag
CO2
GPM
WTD
Bag
ECON
MPG
WTD
MSS
Soot
(mg/mi)
WTD
CPC
Particle
Number
(#/mi)
Test
Number
Odometer
Driver
Step
Test
Start
Date
Control
Number
Fuel
WTD
Bag
THC
GPM
Test 0
1/28/2013
API01
CALEV3_10
0.0138
0.0059
0.0082
0.0090
0.0067
0.0157
0.8893
346.84
24.67
0.595
1.26E+12
2109151
11601
JREED
Test 1
1/29/2013
API01
CALEV3_10
0.0106
0.0035
0.0072
0.0080
0.0104
0.0183
0.3036
344.03
24.93
0.324
8.53E+11
2109166
11621
MWEDDINGTON
Test 2
1/30/2013
API01
CALEV3_10
0.0116
0.0038
0.0080
0.0088
0.0084
0.0172
0.3399
343.98
24.93
0.333
1.02E+12
2109191
11640
MWEDDINGTON
Test 3
1/31/2013
API01
CALEV3_10
0.0109
0.0033
0.0078
0.0086
0.0064
0.0149
0.2390
347.86
24.67
0.263
8.79E+11
2109222
11659
MWEDDINGTON
Test 1
2/4/2013
API01
CALEV3_80
0.0124
0.0047
0.0080
0.0088
0.0141
0.0229
0.5103
341.30
25.11
0.445
1.43E+12
2109276
12017
MWEDDINGTON
Test 2
2/5/2013
API01
CALEV3_80
0.0120
0.0042
0.0080
0.0089
0.0153
0.0241
0.3088
344.43
24.90
0.391
1.18E+12
2109309
12036
MWEDDINGTON
Test 3
2/6/2013
API01
CALEV3_80
0.0148
0.0047
0.0104
0.0114
0.0210
0.0324
0.4717
343.21
24.97
--
1.12E+12
2109340
12046
MWEDDINGTON
Test 1
2/12/2013
API01
CALEV3_10
0.0115
0.0043
0.0073
0.0081
0.0135
0.0216
0.4598
344.96
24.85
0.405
1.20E+12
2109445
12133
MWEDDINGTON
Test 2
2/13/2013
API01
CALEV3_10
0.0105
0.0038
0.0069
0.0076
0.0081
0.0156
0.3275
348.87
24.59
0.519
1.23E+12
2109474
12152
MWEDDINGTON
Test 3
2/14/2013
API01
CALEV3_10
0.0117
0.0042
0.0077
0.0085
0.0058
0.0142
0.4064
348.56
24.60
0.530
1.24E+12
2109509
12172
MWEDDINGTON
Test 0
1/28/2013
API02
CALEV3_10
0.0175
0.0030
0.0147
0.0161
0.0104
0.0265
0.1599
248.62
34.51
0.268
4.76E+11
2109134
6461
MWEDDINGTON
Test 1
1/29/2013
API02
CALEV3_10
0.0148
0.0034
0.0117
0.0129
0.0083
0.0212
0.1380
249.10
34.45
0.299
6.36E+11
2109162
6480
MWEDDINGTON
Test 2
1/30/2013
API02
CALEV3_10
0.0208
0.0033
0.0177
0.0195
0.0075
0.0270
0.1961
250.68
34.22
0.276
7.80E+11
2109187
6499
MWEDDINGTON
Test 3
1/31/2013
API02
CALEV3_10
0.0146
0.0030
0.0117
0.0129
0.0068
0.0197
0.1126
252.62
33.98
0.237
6.97E+11
2109229
6518
MWEDDINGTON
Test 1
2/4/2013
API02
CALEV3_80
0.0212
0.0044
0.0170
0.0187
0.0095
0.0282
0.1929
248.44
34.53
0.372
5.87E+11
2109290
6870
JREED
Test 2
2/5/2013
API02
CALEV3_80
0.0193
0.0044
0.0151
0.0166
0.0166
0.0332
0.2618
250.74
34.19
0.192
5.37E+11
2109312
6889
MWEDDINGTON
Test 3
2/6/2013
API02
CALEV3_80
0.0186
0.0042
0.0146
0.0160
0.0121
0.0281
0.2488
248.54
34.50
0.300
7.75E+11
2109346
6908
MWEDDINGTON
Test 1
2/12/2013
API02
CALEV3_10
0.0117
0.0024
0.0098
0.0108
0.0075
0.0183
0.1285
252.57
33.98
0.251
6.66E+11
2109443
6965
MWEDDINGTON
Test 2
2/13/2013
API02
CALEV3_10
0.0134
0.0024
0.0112
0.0123
0.0099
0.0222
0.1432
249.15
34.44
0.280
6.68E+11
2109470
6984
MWEDDINGTON
Test 3
2/18/2013
API02
CALEV3_10
0.0166
0.0034
0.0137
0.0150
0.0058
0.0209
0.1149
254.24
33.76
0.191
5.91E+11
2109547
7022
MWEDDINGTON
Page 44
Table 14. Fuel Sulfur Reversibility Study Dataset for Analysis, API03
WTD
Bag
CH4
GPM
WTD
Bag
NMHC
GPM
WTD
Bag
NMOG
GPM
WTD
Bag
NOx
GPM
WTD
Bag
NMOG
+NOx
GPM
WTD
Bag
CO
GPM
WTD
Bag
CO2
GPM
WTD
Bag
ECON
MPG
WTD
MSS
Soot
(mg/mi)
WTD
CPC
Particle
Number
(#/mi)
Test
Number
Odometer
Driver
Step
Test
Start
Date
Control
Number
Fuel
WTD
Bag
THC
GPM
Test 0
2/5/2013
API03
CALEV3_10
0.0129
0.0024
0.0106
0.0117
0.0052
0.0169
0.2019
311.30
27.56
3.725
5.74E+12
2109305
7639
MWEDDINGTON
Test 1
2/6/2013
API03
CALEV3_10
0.0135
0.0023
0.0114
0.0126
0.0053
0.0179
0.2046
317.07
27.06
3.613
5.57E+12
2109350
7658
MWEDDINGTON
Test 2
2/7/2013
API03
CALEV3_10
0.0090
0.0015
0.0075
0.0083
0.0052
0.0135
0.1537
316.07
27.16
3.471
5.64E+12
2109383
7677
MWEDDINGTON
Test 3
2/8/2013
API03
CALEV3_10
0.0096
0.0027
0.0072
0.0079
0.0048
0.0127
0.1867
311.18
27.58
3.798
5.76E+12
2109397
7695
MWEDDINGTON
Test 1
2/13/2013
API03
CALEV3_80
0.0120
0.0025
0.0096
0.0106
0.0074
0.0180
0.2143
314.69
27.27
4.051
6.60E+12
2109479
8059
MWEDDINGTON
Test 2
2/14/2013
API03
CALEV3_80
0.0154
0.0032
0.0124
0.0136
0.0095
0.0232
0.2705
313.31
27.38
4.066
6.57E+12
2109500
8078
MWEDDINGTON
Test 3
2/15/2013
API03
CALEV3_80
0.0208
0.0027
0.0183
0.0201
0.0097
0.0298
0.2083
318.04
26.97
4.086
6.73E+12
2109528
8097
MWEDDINGTON
Test 1
2/19/2013
API03
CALEV3_10
0.0180
0.0044
0.0146
0.0161
0.0066
0.0227
0.2654
323.05
26.55
3.602
5.76E+12
2109560
8131
MWEDDINGTON
Test 2
2/20/2013
API03
CALEV3_10
0.0103
0.0019
0.0086
0.0094
0.0065
0.0160
0.1468
318.53
26.95
--
--
2109578
8150
MWEDDINGTON
Test 3
2/21/2013
API03
CALEV3_10
0.0145
0.0024
0.0122
0.0135
0.0056
0.0191
0.1925
324.37
26.46
3.385
5.59E+12
2109601
8169
MWEDDINGTON
Page 45
Table 15. Fuel Sulfur Reversibility Study Dataset for Analysis, API04
Step
Test
Start
Date
Control
Number
Fuel
WTD
Bag
THC
GPM
WTD
Bag
CH4
GPM
WTD
Bag
NMHC
GPM
WTD
Bag
NMOG
GPM
WTD
Bag
NOx
GPM
WTD
Bag
NMOG
+NOx
GPM
WTD
Bag
CO
GPM
WTD
Bag
CO2
GPM
WTD
Bag
ECON
MPG
WTD
MSS
Soot
(mg/mi)
WTD
CPC
Particle
Number
(#/mi)
Test
Number
Odometer
Driver
API04 Initial Sequence
Test 0
2/5/2013
API04
CALEV3_10
0.0105
0.0048
0.0065
0.0072
0.0054
0.0126
0.1430
260.24
32.98
0.796
2.58E+12
2109301
5920
MWEDDINGTON
Test 1
2/6/2013
API04
CALEV3_10
0.0128
0.0033
0.0097
0.0107
0.0038
0.0144
0.1822
261.68
32.79
0.723
2.49E+12
2109347
5939
MWEDDINGTON
Test 2
2/7/2013
API04
CALEV3_10
0.0089
0.0032
0.0062
0.0068
0.0057
0.0125
0.1462
263.43
32.58
0.743
2.51E+12
2109378
5959
MWEDDINGTON
Test 3
2/8/2013
API04
CALEV3_10
0.0108
0.0028
0.0082
0.0091
0.0042
0.0133
0.2359
261.46
32.81
0.831
2.61E+12
2109396
5978
MWEDDINGTON
Test 1
2/13/2013
API04
CALEV3_80
0.0116
0.0042
0.0076
0.0084
0.0051
0.0135
0.2770
269.64
31.80
1.200
3.46E+12
2109481
6349
MWEDDINGTON
Test 2
2/14/2013
API04
CALEV3_80
0.0143
0.0041
0.0104
0.0114
0.0060
0.0175
0.3353
267.44
32.05
1.112
3.28E+12
2109504
6368
MWEDDINGTON
Test 3
2/15/2013
API04
CALEV3_80
0.0120
0.0036
0.0086
0.0095
0.0059
0.0154
0.3288
266.71
32.14
1.062
2.49E+12
2109527
6388
MWEDDINGTON
Test 1
2/21/2013
API04
CALEV3_10
0.0107
0.0022
0.0087
0.0095
0.0059
0.0154
0.1699
269.07
31.89
--
3.30E+12
2109594
6461
MWEDDINGTON
Test 2
2/22/2013
API04
CALEV3_10
0.0091
0.0027
0.0067
0.0073
0.0056
0.0129
0.1450
266.82
32.17
1.010
3.09E+12
2109617
6480
MWEDDINGTON
Test 3
2/23/2013
API04
CALEV3_10
0.0079
0.0024
0.0056
0.0062
0.0045
0.0107
0.1608
267.77
32.05
1.053
3.14E+12
2109628
6498
MWEDDINGTON
API04 Repeat Sequence
Test 0
5/8/2013
API04
CALEV3_10
0.0107
0.0017
0.0091
0.0100
0.0057
0.0157
0.1453
257.81
33.29
0.690
2.29E+12
2110584
7168
MWEDDINGTON
Test 1
5/9/2013
API04
CALEV3_10
0.0092
0.0019
0.0074
0.0082
0.0076
0.0158
0.1192
261.53
32.82
0.783
2.46E+12
2110603
7187
MWEDDINGTON
Test 2
5/13/2013
API04
CALEV3_10
0.0084
0.0026
0.0059
0.0065
0.0059
0.0124
0.1228
264.28
32.48
0.887
2.85E+12
2110638
7245
MWEDDINGTON
Test 3
5/14/2013
API04
CALEV3_10
0.0083
0.0026
0.0059
0.0065
0.0068
0.0133
0.1583
265.36
32.34
0.959
2.84E+12
2110647
7265
MWEDDINGTON
Test 1
5/16/2013
API04
CALEV3_80
0.0146
0.0045
0.0103
0.0113
0.0075
0.0189
0.2105
261.32
32.83
0.783
2.84E+12
2110675
7615
MWEDDINGTON
Test 2
5/17/2013
API04
CALEV3_80
0.0100
0.0040
0.0062
0.0068
0.0080
0.0148
0.2937
265.49
32.30
0.913
2.74E+12
2110681
7634
MWEDDINGTON
Test 3
5/18/2013
API04
CALEV3_80
0.0096
0.0033
0.0065
0.0071
0.0121
0.0192
0.1932
259.57
33.05
0.877
2.80E+12
2110686
7653
MWEDDINGTON
Test 1
5/21/2013
API04
CALEV3_10
0.0079
0.0021
0.0059
0.0065
0.0081
0.0147
0.1065
263.14
32.62
0.834
2.85E+12
2110696
7688
MWEDDINGTON
Test 2
5/22/2013
API04
CALEV3_10
0.0090
0.0029
0.0062
0.0069
0.0060
0.0128
0.1585
264.78
32.41
0.952
3.03E+12
2110706
7707
MWEDDINGTON
Test 3
5/23/2013
API04
CALEV3_10
0.0072
0.0023
0.0050
0.0055
0.0055
0.0110
0.1359
262.81
32.66
0.802
2.64E+12
2110714
7727
MWEDDINGTON
Page 46
Table 16. Fuel Sulfur Reversibility Study Dataset for Analysis, API05 and API06
WTD
Bag
CH4
GPM
WTD
Bag
NMHC
GPM
WTD
Bag
NMOG
GPM
WTD
Bag
NOx
GPM
WTD
Bag
NMOG
+NOx
GPM
WTD
Bag
CO
GPM
WTD
Bag
CO2
GPM
WTD
Bag
ECON
MPG
WTD
MSS
Soot
(mg/mi)
WTD
CPC
Particle
Number
(#/mi)
Test
Number
Odometer
Driver
Step
Test
Start
Date
Control
Number
Fuel
WTD
Bag
THC
GPM
Test 0
3/21/2013
API05
PRLEV3_10
0.0151
0.0051
0.0102
0.0113
0.0126
0.0239
0.4261
312.62
27.21
1.137
3.73E+12
2110059
9803
MWEDDINGTON
Test 1
3/26/2013
API05
PRLEV3_10
0.0185
0.0076
0.0113
0.0125
0.0178
0.0303
0.4636
311.75
27.28
1.404
4.46E+12
2110094
9864
MWEDDINGTON
Test 2
3/27/2013
API05
PRLEV3_10
0.0150
0.0069
0.0085
0.0093
0.0137
0.0230
0.4684
313.03
27.17
1.277
4.34E+12
2110113
9885
MWEDDINGTON
Test 3
3/28/2013
API05
PRLEV3_10
0.0146
0.0064
0.0086
0.0094
0.0115
0.0209
0.5052
314.29
27.05
1.009
4.11E+12
2110135
9903
MWEDDINGTON
Test 1
4/1/2013
API05
PRLEV3_80
0.0160
0.0067
0.0096
0.0106
0.0158
0.0265
0.5282
310.53
27.37
1.306
4.24E+12
2110152
10251
MWEDDINGTON
Test 2
4/2/2013
API05
PRLEV3_80
0.0172
0.0080
0.0097
0.0106
0.0166
0.0272
0.5556
307.45
27.64
1.057
3.56E+12
2110167
10271
MWEDDINGTON
Test 3
4/3/2013
API05
PRLEV3_80
0.0151
0.0069
0.0085
0.0094
0.0393
0.0487
0.4402
312.44
27.22
0.920
3.32E+12
2110181
10290
MWEDDINGTON
Test 1
4/4/2013
API05
PRLEV3_10
0.0155
0.0055
0.0103
0.0113
0.0147
0.0260
0.4753
313.30
27.14
0.785
2.98E+12
2110203
10324
MWEDDINGTON
Test 2
4/5/2013
API05
PRLEV3_10
0.0173
0.0073
0.0104
0.0115
0.0169
0.0283
0.4556
310.19
27.41
0.807
3.02E+12
2110219
10343
MWEDDINGTON
Test 3
4/6/2013
API05
PRLEV3_10
0.0144
0.0066
0.0082
0.0091
0.0102
0.0192
0.5537
306.94
27.69
0.774
2.80E+12
2110229
10363
MWEDDINGTON
Test 0
2/12/2013
API06
CALEV3_10
0.0200
0.0036
0.0169
0.0186
0.0204
0.0390
0.3224
327.92
26.15
0.142
3.19E+11
2109448
5505
MWEDDINGTON
Test 1
2/13/2013
API06
CALEV3_10
0.0198
0.0043
0.0161
0.0177
0.0279
0.0456
0.2907
326.22
26.29
0.120
2.55E+11
2109476
5524
MWEDDINGTON
Test 2
2/14/2013
API06
CALEV3_10
0.0182
0.0043
0.0141
0.0155
0.0243
0.0398
0.3006
322.71
26.58
0.153
3.46E+11
2109497
5543
MWEDDINGTON
Test 3
2/15/2013
API06
CALEV3_10
0.0184
0.0052
0.0142
0.0156
0.0205
0.0361
0.3297
324.11
26.46
0.071
2.47E+11
2109524
5562
MWEDDINGTON
Test 1
2/18/2013
API06
CALEV3_80
0.0416
0.0087
0.0346
0.0381
0.0284
0.0665
0.6708
319.02
26.83
0.265
2.80E+11
2109543
5908
MWEDDINGTON
Test 2
2/19/2013
API06
CALEV3_80
0.0226
0.0058
0.0173
0.0191
0.0227
0.0418
0.3310
327.05
26.22
0.079
2.33E+11
2109556
5927
MWEDDINGTON
Test 3
2/20/2013
API06
CALEV3_80
0.0212
0.0053
0.0167
0.0184
0.0248
0.0432
0.3342
327.20
26.21
0.157
3.04E+11
2109574
5946
MWEDDINGTON
Test 1
2/21/2013
API06
CALEV3_10
0.0179
0.0048
0.0143
0.0158
0.0231
0.0389
0.2261
326.56
26.27
0.129
3.30E+11
2109597
5980
MWEDDINGTON
Test 2
2/22/2013
API06
CALEV3_10
0.0186
0.0042
0.0149
0.0164
0.0225
0.0389
0.2880
326.22
26.29
0.133
3.15E+11
2109614
5999
MWEDDINGTON
Test 3
2/23/2013
API06
CALEV3_10
0.0184
0.0046
0.0150
0.0165
0.0238
0.0402
0.3165
325.02
26.39
0.107
2.52E+11
2109627
6018
MWEDDINGTON
Page 47
8.0 Sulfur Reversibility Study Results - Statistical Analysis
8.1
Statistical Analysis Approach
A statistical analysis was performed to determine if the exhaust emissions effects caused by exposure to
80 ppm sulfur fuel were reversible, after the vehicle was refueled with 10 ppm sulfur fuel.
Independent variables included the vehicle model and state. The state is defined as tests performed
either before or after the 80 ppm sulfur fuel exposure. The analysis approach allowed conclusions to be
drawn for individual vehicles, and for the combined test fleet of six vehicles. Dependent variables (or
responses) included NMOG, NOx, CO, soot and PN. Weighted certification-quality bag emissions were
the measure of most importance, and used for the statistical analysis due to the implication of fuel
sulfur content on proposed EPA Tier 3 regulatory requirements.
There were nominally ten data points for each reversibility sequence run: four baseline tests run on 10
ppm sulfur fuel, three tests using 80 ppm fuel, and three tests after the vehicle was switched back to 10
ppm fuel (Section 3 and 7). Mean emissions were calculated for the baseline tests run on 10 ppm
sulfur fuel, ̅ . Mean emissions were also calculated for the reversibility tests run after the vehicle was
switched back to 10 ppm fuel, ̅ . Confidence intervals were estimated for the difference of the means,
̅
̅ . If the confidence interval for the difference in mean emissions included zero, then mean
emissions before and after exposure to the 80 ppm fuel were not statistically different and the
hypothesis that the sulfur effects on emissions were irreversible would be rejected.
The statistical analysis followed the approach used for a previous CRC sulfur effects reversibility study
[Ref. 4]. This analysis approach has also been documented and applied for small sample sizes in the
medical field [Ref. 18]. The equations from the latter reference were used to independently confirm the
correct application of the analysis method to the present study.
To assess the validity of common statistics assumptions, the data was checked for normality using the
Kolmogorov–Smirnov test. There was no basis to reject normality for HC, CH4 and CO emissions.
However, normality was rejected for NOx, soot and PN emissions (p-value≤0.05, Figure 24). When the
sample size is small as in this study, the mean and standard deviations may be skewed by extreme data
values present in non-normal distributions. Consistent with previously published vehicle exhaust
emissions studies, natural log transformed emissions more closely adhered to normality assumptions
and were used for the statistical analysis.
Natural log transformations were performed for all
dependent variables (or responses) of interest, including NMOG, NOx, CO, soot and PN.
For the following equations, the symbol and subscript designates natural log transformed values, and
the symbol and subscript represents values in the raw system of measure. In this context, the values
of correspond to bag emissions expressed in measured units and are not to be confused with raw
exhaust stream measurements. The index
corresponds to the baseline emissions data, and
corresponds to the reversibility emissions data using 10 ppm fuel, taken after the exposure to 80 ppm
fuel. Subsequently, the index is referred to as the state.
Page 48
Figure 24. Data Distributions for NOx and Soot Emissions
From the measured emissions data designated
Eq. 1
Using this natural log transformed data, the transformed mean ̅ and transformed standard deviation
were calculated for each vehicle. In the raw system, the mean and standard deviation were
determined as
Eq. 2
(
)
(
)
Eq. 3
√(
(
)
)
(
)
(
)
The difference in the means between the two states was
Eq. 4
The standard error used for confidence interval calculation around
was
Eq. 5
(
)
√
( )
( )
where from Taylor series approximation and the number of samples for the state,
,
Page 49
Eq. 6
( )
(
)
(
(
)
)
The 95% confidence intervals were then calculated for each vehicle using the Student-t distribution.
Degrees of freedom were estimated using the Satterthwaite formula.
Eq. 7
(
)
The data for all six vehicles were pooled together in order to make conclusions about reversibility for the
test fleet. The approach for pooling the data was also taken from [Ref. 18].
The pooled standard deviation in the log transformed system was calculated by
Eq. 8
(
√
)
(
)
(
)
where the index represented the number of groups being pooled, or
for the number of
vehicles times two states being pooled. The pooled mean for each state, ̅ , was calculated by
averaging ̅ from the six vehicles. The standard error used for pooled calculations was
Eq. 9
(
)
√
(
)
(
(
̅
)
(
̅
)
(
( ̅
(
)
( ̅
)
))
)
The pooled values for ̅ ,
, and (
) were then inputs for equations 2, 3, 4 and 7 to determine
the difference of means and confidence intervals for the fleet of vehicles tested. Confidence intervals
pertaining to the fleet difference of means were much narrower due to the better estimates of pooled
standard errors, and because of the greatly increased degrees of freedom for the t statistics.
One key difference between the present study and the CRC reversibility study [Ref. 4] was the number
of tests used for comparing reversibility. In the CRC study, eight tests were run before and six tests were
run after the high sulfur fuel exposure. In contrast, four tests were run before and three tests were run
after the 80 ppm fuel exposure in the present study. Therefore, the criteria for reversibility may be
considered more stringent for the present study because only half the time was allowed for emissions
stabilization.
Page 50
8.2
Statistical Analysis Results and Discussion
The reversibility of the sulfur effects was evaluated by comparing emissions before and after the
exposure to 80 ppm fuel. Tests before and after the exposure were run using 10 ppm sulfur fuel. The
mean emissions after the exposure were subtracted from the mean baseline emissions before the
exposure and 95% confidence intervals were calculated for the difference of the means per Section 8.1.
The difference in the means is shown in Figure 25. A negative mean difference result indicated the mean
emissions were higher after the 80 ppm fuel exposure. If the confidence interval included zero, then
mean emissions before and after exposure to the 80 ppm fuel were not statistically different and the
hypothesis that the sulfur effects on emissions were irreversible would be rejected. If the hypothesis
was rejected, the emissions were considered to be reversible.
NMOG, NOx, and CO were reversible for all vehicles in the study following the 80 ppm fuel exposure.
Some of the confidence intervals were quite large for individual vehicle, reflecting the variation in
emissions from Figures 11-16. Confidence intervals for fleet means were much narrower due to the
better estimates of pooled standard errors, and because of the greatly increased degrees of freedom for
the t statistics.
Soot and PN emissions were reversible for the fleet, and also for five of the six vehicles. Soot and PN
emissions were not reversible for the initial sequence tests for vehicle API04, as the mean was negative
and the confidence interval did not include zero (Figure 25). The data from Figure 14 illustrate higher
soot and PN emissions following the 80 ppm fuel exposure (Figure 14 “Initial Sequence”). The soot and
PN emissions results were further explored for vehicle API04.
The soot and particle number measurements are completely independent of each other (Section 6.2).
Soot and PN results for all FTP75 emissions tests performed for vehicle API04 are shown on Figure 26. A
strong linear correlation existed between soot mass and PN emissions, as expected since both
instruments measured elemental carbon and excluded volatile organic and sulfate aerosols. The strong
soot and PN correlation (R2≥0.9) confirmed there were no measurement anomalies. The soot emissions
varied widely for this GDI-equipped vehicle, ranging from 0.69 to 1.69 mg/mile over the FTP75 for 10
ppm sulfur fuel. This large range in soot emissions eclipsed the soot emissions for tests run using 80
ppm fuel, which ranged from 0.78 to 1.2 mg/mile. The test-to-test variability of the soot and PN
emissions from vehicle API04 by far eclipsed the fuel sulfur effect, and indicated that the irreversibility
of soot and PN emissions due to fuel sulfur (as shown in Figure 25) was a false conclusion. Putting this
finding into perspective, the total PM for API04 is about 1.5/0.62 soot fraction = 2.4 mg/mile compared
to a 10 mg/mile Tier 2 (and SULEV-II) standard. This finding is foreshadowing the difficulty of certifying
a GDI-equipped vehicle to an EPA Tier 3/ California LEVIII PN standard of 1 to 3 mg/mile.
In order to further determine if the irreversibility of soot and PN emissions for vehicle API04 was caused
by fuel sulfur, the reversibility test sequence was repeated. This dataset is referred to as the “Repeat
Sequence” throughout the report. The Repeat Sequence test results for Soot and PN were substantially
different than the Initial Sequence results (Figure 14), again suggesting the test-to-test variability is high
for vehicle API04. The data from the Repeat Sequence was used for all subsequent statistical analysis
presented in this section. The difference in mean emissions and confidence intervals are provided in
Figure 27. Using the Repeat Sequence results, the hypothesis that soot and PN emissions were
irreversible for vehicle API04 was rejected.
Page 51
Figure 25. Difference in Mean Emissions and 95% Confidence Intervals for 10 ppm Sulfur Fuel
Before – After High Sulfur Fuel Exposure, API04 Initial Sequence Data
Page 52
Figure 26. Soot and PN Correlation for Vehicle API04, 10 ppm and 80 ppm Fuels
For individual vehicles and the vehicle fleet, NMOG, NOx, CO, Soot and PN emissions were found to be
reversible following exposure to 80 ppm sulfur fuel (Figure 27). Note that some of the vehicle mean
difference values were positive and negative, indicating that both small emissions increases and
decreases were measured after the exposure to 80 ppm sulfur fuel. Vehicle API05 showed a soot and
PN emissions decrease after 80 ppm fuel exposure and the confidence interval did not include zero
indicating the difference was statistically significant. This result is likely due to the test-to-test variability
in vehicle emissions and not a fuel sulfur effect, as was concluded for vehicle API04 above.
The mean values, 95% confidence intervals, standard deviation and coefficient of variation are tabulated
for each state, each vehicle and for the fleet of six vehicles in Table 17. Using the same methodology
described in Section 8.1, vehicle emissions using the 80 ppm fuel were compared to the mean baseline
emissions using 10 ppm sulfur fuel to quantify the sensitivity to sulfur. Fleet average gaseous emissions
increased when the vehicles were conditioned and tested using the 80 ppm sulfur fuel relative to the
baseline tests. Fleet NMOG emissions increased by 20% (0.002 g/mile change), NOx increased by 58%
(0.006 g/mile change), and CO increased by 31% (0.078 g/mile change) for 80 ppm sulfur fuel, relative to
the baseline emissions using 10 ppm fuel with greater than 95% confidence. Fleet soot and PN
emissions were not statistically different for 80 ppm fuel, compared to 10 ppm fuel.
Mean emissions increases for the 80 ppm fuel were conclusive for the fleet due to narrow confidence
intervals resulting from pooled variances and greater degrees of freedom (Section 8.1). With a few
exceptions, emissions increases for the 80 ppm fuel were not statistically conclusive for individual
vehicles due to much wider confidence intervals. Four conclusions were reached with regards to
individual vehicles with greater than 95% confidence:




Vehicle API02 (Civic) CO emissions increased by 54% (0.083 g/mile change) when run on 80 ppm
sulfur fuel compared to baseline emissions.
Vehicle API03 (Sonata) NOx emissions increased by 74% (0.004 g/mile change) when run on 80
ppm sulfur fuel, compared to baseline emissions. Nevertheless, mean emissions of 0.009 g/mile
remained well under the SULEV-II standard of 0.02 g/mile when fueled with 80 ppm fuel.
Vehicle API03 (Sonata) soot emissions increased by 11% (0.41 mg/mile change) when run on 80
ppm sulfur fuel compared to baseline emissions.
Vehicle API03 (Sonata) PN emissions increased by 17% (9.6x1011 #/mile change) when run on 80
ppm sulfur fuel compared to baseline emissions.
Page 53
Figure 27. Difference in Mean Emissions and 95% Confidence Intervals for 10 ppm Sulfur Fuel
Before – After High Sulfur Fuel Exposure, API04 Repeat Sequence Data
Page 54
Table 17. Mean Emissions and 95% Confidence Intervals from Statistical Analysis
Baseline Tests, 10 ppm Sulfur Fuel
Mean
NMOG (g/mile)
API01
API02
API03
API04
API05
API06
Fleet (Pooled)
NOx (g/mile)
API01
API02
API03
API04
API05
API06
Fleet (Pooled)
CO (g/mile)
API01
API02
API03
API04
API05
API06
Fleet (Pooled)
Soot (mg/mile)
API01
API02
API03
API04
API05
API06
Fleet (Pooled)
PN (#xE12/mile)
API01
API02
API03
API04
API05
API06
Fleet (Pooled)
High Sulfur Exposure, 80 ppm Sulfur Fuel
95% CI
Stdev
COV
Mean
Reversibility Tests, 10 ppm Sulfur Fuel
95% CI
Stdev
COV
Mean
95% CI
Stdev
COV
0.0086
0.0154
0.0102
0.0078
0.0107
0.0169
0.0111
±
±
±
±
±
±
±
0.0007
0.0049
0.0039
0.0027
0.0024
0.0024
0.0008
0.0005
0.0031
0.0024
0.0017
0.0015
0.0015
0.0019
0.054
0.200
0.239
0.213
0.143
0.091
0.170
0.0097
0.0171
0.0150
0.0085
0.0102
0.0258
0.0133
±
±
±
±
±
±
±
0.0036
0.0034
0.0124
0.0061
0.0019
0.0274
0.0017
0.0014
0.0014
0.0050
0.0024
0.0008
0.0111
0.0034
0.148
0.080
0.333
0.286
0.074
0.429
0.258
0.0080
0.0128
0.0132
0.0063
0.0106
0.0162
0.0107
±
±
±
±
±
±
±
0.0012
0.0054
0.0090
0.0019
0.0035
0.0009
0.0008
0.0005
0.0022
0.0036
0.0007
0.0014
0.0004
0.0016
0.058
0.169
0.276
0.118
0.133
0.023
0.152
0.0080
0.0083
0.0051
0.0065
0.0140
0.0233
0.0095
±
±
±
±
±
±
±
0.0029
0.0024
0.0004
0.0013
0.0042
0.0056
0.0007
0.0018
0.0015
0.0002
0.0008
0.0026
0.0035
0.0016
0.228
0.185
0.046
0.129
0.189
0.151
0.165
0.0169
0.0129
0.0089
0.0093
0.0248
0.0254
0.0150
±
±
±
±
±
±
±
0.0090
0.0091
0.0033
0.0061
0.0336
0.0071
0.0022
0.0036
0.0037
0.0013
0.0025
0.0136
0.0029
0.0044
0.214
0.284
0.149
0.264
0.548
0.113
0.291
0.0094
0.0078
0.0063
0.0066
0.0141
0.0231
0.0100
±
±
±
±
±
±
±
0.0104
0.0052
0.0014
0.0034
0.0093
0.0015
0.0013
0.0042
0.0021
0.0006
0.0014
0.0037
0.0006
0.0025
0.449
0.270
0.089
0.206
0.265
0.027
0.253
0.455
0.153
0.187
0.137
0.466
0.311
0.252
±
±
±
±
±
±
±
0.451
0.058
0.039
0.030
0.052
0.029
0.029
0.286
0.036
0.025
0.019
0.033
0.018
0.069
0.629
0.238
0.132
0.136
0.070
0.059
0.273
0.436
0.236
0.232
0.234
0.509
0.456
0.330
±
±
±
±
±
±
±
0.298
0.096
0.083
0.130
0.156
0.477
0.040
0.120
0.039
0.033
0.053
0.063
0.193
0.081
0.275
0.165
0.144
0.224
0.123
0.422
0.245
0.400
0.129
0.205
0.135
0.496
0.278
0.241
±
±
±
±
±
±
±
0.172
0.035
0.154
0.068
0.127
0.121
0.023
0.069
0.014
0.062
0.027
0.051
0.049
0.046
0.173
0.110
0.303
0.203
0.103
0.175
0.189
0.38
0.27
3.65
0.83
1.21
0.12
0.60
±
±
±
±
±
±
±
0.22
0.04
0.23
0.19
0.28
0.07
0.06
0.14
0.03
0.14
0.12
0.17
0.04
0.13
0.360
0.097
0.039
0.145
0.144
0.357
0.224
0.42
0.29
4.07
0.86
1.10
0.18
0.66
±
±
±
±
±
±
±
0.10
0.25
0.04
0.17
0.49
0.29
0.10
0.04
0.10
0.02
0.07
0.20
0.12
0.20
0.093
0.346
0.004
0.080
0.178
0.671
0.304
0.49
0.24
3.49
0.86
0.79
0.12
0.57
±
±
±
±
±
±
±
0.18
0.12
0.38
0.19
0.04
0.04
0.03
0.07
0.05
0.15
0.08
0.02
0.01
0.07
0.151
0.199
0.044
0.090
0.021
0.116
0.120
1.01
0.65
5.68
2.61
4.16
0.29
1.51
±
±
±
±
±
±
±
0.29
0.22
0.14
0.46
0.52
0.08
0.09
0.18
0.14
0.09
0.29
0.33
0.05
0.22
0.179
0.214
0.016
0.110
0.079
0.168
0.144
1.25
0.64
6.63
2.79
3.72
0.27
1.57
±
±
±
±
±
±
±
0.40
0.31
0.20
0.12
1.18
0.09
0.10
0.16
0.12
0.08
0.05
0.47
0.04
0.19
0.129
0.193
0.012
0.017
0.127
0.138
0.122
1.22
0.64
5.68
2.84
2.93
0.30
1.50
±
±
±
±
±
±
±
0.06
0.11
0.30
0.50
0.30
0.11
0.06
0.02
0.04
0.12
0.20
0.12
0.04
0.11
0.019
0.069
0.021
0.070
0.041
0.144
0.074
Page 55
9.0 Summary and Conclusions

Six late model vehicles were tested to determine if the exhaust emissions effects caused by
exposure to 80 ppm sulfur fuel were reversible, after the vehicle was refueled with 10 ppm
sulfur fuel. The reversibility test sequence included four baseline tests run on 10 ppm sulfur
fuel, three high sulfur fuel exposure tests using 80 ppm fuel, and three tests after the vehicle
was switched back to 10 ppm fuel.

Gaseous exhaust emissions were higher for the vehicles conditioned and tested using 80 ppm
sulfur fuel, relative to baseline tests run using 10 ppm fuel. Mean emissions increased for
vehicles run on the 80 ppm fuel as follows, with greater than 95% confidence:
o Fleet average NMOG increased by 20% (0.002 g/mile change)
o Fleet average NOx increased by 58% (0.006 g/mile change)
o Fleet average CO increased by 31% (0.078 g/mile change)
o Vehicle API02 (Civic) CO emissions increased by 54% (0.083 g/mile change)
o Vehicle API03 (Sonata) NOx emissions increased by 74% (0.004 g/mile change), noting
that mean emissions of 0.009 g/mile remained well under the SULEV-II standard

For the test fleet of six vehicles, average soot and PN emissions were not statistically different
for 80 ppm fuel compared to 10 ppm fuel results. Only vehicle API03 (Sonata), the highest PM
emitter in the study, had higher soot and PN emissions using 80 ppm fuel:
o Vehicle API03 (Sonata) soot emissions increased by 11% (0.41 mg/mile change)
o Vehicle API03 (Sonata) PN emissions increased by 17% (9.6x1011 #/mile change)

A statistical analysis was performed to determine if the exhaust emissions effects caused by
exposure to 80 ppm sulfur fuel were reversible, after the vehicle was refueled with 10 ppm
sulfur fuel.

For each vehicle tested on 10 ppm sulfur fuel, the NMOG, NOx, CO, Soot and PN emissions were
found to be reversible following exposure to 80 ppm sulfur fuel. There was greater than 95%
confidence that the differences in the mean emissions values measured before and after the
high sulfur fuel exposure were not statistically different.

For the fleet of six vehicles combined, the NMOG, NOx, CO, Soot and PN emissions were found
to be reversible following exposure to 80 ppm sulfur fuel.

Vehicles equipped with GDI engines had about five to seven times higher soot mass and particle
number emissions on average compared to the SFI-equipped vehicles.

Vehicles equipped with GDI engines had very high variability in soot and PN emissions. The
vehicle emissions variability was shown to be far larger than the fuel sulfur effect under study.
Page 56
10.0 References
1. U.S. Environmental Protection Agency, “EPA Proposes Tier 3 Motor Vehicle Emission and Fuel
Standards”, Office of Transportation and Air Quality EPA-420-F-13-016, March 2013.
2. Benson, J., Burns, V., Koehl, W., Gorse, R., Painter, L., Hochhauser, A., Reuter, R., "Effects of
Gasoline Sulfur Level on Mass Exhaust Emissions - Auto/Oil Air Quality Improvement Research
Program," SAE Technical Paper 912323, 1991.
3. Petit, A., Jeffrey, J., Palmer, F., and Steinbrink, R., "European Programme on Emissions, Fuels and
Engine Technologies (EPEFE) - Emissions from Gasoline Sulphur Study," SAE Technical Paper
961071, 1996.
4. Schleyer, C., Eng, K., Gorse, R., Gunst, R., Eckstrom, J., Freel, J., Natarajan, M., Schlenker, A.,
“Reversibility of Sulfur Effects on Emissions of California Low Emission Vehicles”, SAE Technical
Paper 1999-01-1544, 1999.
5. Ball, D., Clark, D., Moser, D., “Effects of Fuel Sulfur on FTP NOx Emissions from a PZEV 4 Cylinder
Application”, SAE Technical Paper 2011-01-0300, April 2011.
6. US Department of Transportation, Federal Highway Administration, “Posted Speed Limits by
Functional System”, Highway Information Quarterly Newsletter, April 2002,
http://www.fhwa.dot.gov/ohim/hiq/hiqapr02.htm#topicA
7. Dudek, W., “CRC Project No. E-87-1 Mid-Level Ethanol Blends Catalyst Durability Study
Screening”, Transportation Research Center Inc., June 2009.
8. California Air Resources Board, “California 2015 and subsequent model criteria pollutant
exhaust emission standards and test procedures and 2017 and subsequent model greenhouse
gas exhaust emissions standards and test procedures for passenger cars, light-duty trucks, and
medium-duty vehicles,” pp. II-3 – II-4.
9. Koehl, W., Benson, J., Burns, V., Gorse, R. et al., "Effects of Gasoline Sulfur Level on Exhaust
Mass and Speciated Emissions: The Question of Linearity - Auto/Oil Air Quality Improvement
Program," SAE Technical Paper 932727, 1993.
10. U.S. Environmental Protection Agency Annual Certification Test Results & Database,
http://www.epa.gov/oms/crttst.htm.
11. Kubsh, J., “Advanced Emission Control Systems for Gasoline and Diesel Engines”, SAE OBD
Symposium, August 2010.
12. Sims, G., Johri, S., “Catalyst Performance Study Using Taguchi Methods”, SAE Technical Paper
881589, 1988.
Page 57
13. Burkholder, S., Cooper, B., “Effect of Aging and Testing Conditions on Catalyst Performance”,
SAE Technical Paper 911734, 1991.
14. California Air Resources Board, “California Evaluation Procedures for New Aftermarket Catalytic
Convertors”, October 2007.
15. Sluder, S., West, B., “NMOG Emissions Characterizations and Estimation for Vehicles Using
Ethanol-Blended Fuels”, Oak Ridge National Laboratory Report ORNL/TM-2011/461, October
2011.
16. West, B., Sluder, S., Knoll, K., Orban, J., Feng, J., “Intermediate Ethanol Blends Catalyst Durability
Program”, Oak Ridge National Laboratory Report ORNL/TM-2011/234, February 2012.
17. Vertin, K., Glinsky, G., Reek, A., “Comparative Emissions Testing of Vehicles Aged on E0, E15 and
E20 Fuels”, National Renewable Energy Laboratory Subcontractor Report NREL/SR-5400-55778,
August 2012.
18. Higgins, J., White, I., Anzures-Cabrera, J., “Meta-analysis of Skewed Data: Combining Results
Reported on Log-Transformed or Raw Scales”, Stat Med. 2008 December 20; 27(29): 6072–6092.
Page 58
11.0 Appendices
11.1 Fuel Sulfur Monitoring Results for Emissions Test Fuels
REGULAR OCTANE
Fuel Name
Lab
Sample Collection
Date
CALEV3_10
CALEV3_10
CALEV3_10
CALEV3_80
CALEV3_80
CALEV3_80
CALEV3_80
Haltermann
SGS-OGC
SGS-OGC
Haltermann
SGS-OGC
SGS-OGC
SGS-OGC
Batch
Tote (Avg 5 drums)
Drum
Tote
Drum 1
Drum 2
Drum 3
11/7/2012
12/19/2012
1/31/2013
11/15/2012
12/19/2012
1/31/2013
1/31/2013
ASTM
D5453
Sulfur
(ppm)
9
9
8.3
79
81
82
80
Target
Sulfur
(ppm)
Sulfur
Difference
(ppm)
10
10
10
80
80
80
80
-1.0
-1.0
-1.7
-1.0
1.0
2.0
0.0
Target
Sulfur
(ppm)
Sulfur
Difference
(ppm)
10
10
10
80
80
-1.0
-1.0
-1.5
-1.6
-1.2
PREMIUM OCTANE
Fuel Name
Lab
Sample Collection
Date
PRLEV3_10
PRLEV3_10
PRLEV3_10
PRLEV3_80
PRLEV3_80
Haltermann
SGS-OGC
SGS-OGC
SGS-OGC
SGS-OGC
Batch
Drum 1
Drum 2
Drum 1, Sample 1
Drum 1, Sample 2
10/23/2012
12/19/2012
1/31/2013
3/19/2013
3/19/2013
ASTM
D5453
Sulfur
(ppm)
9
9
8.5
78.4
78.8
Page 59
11.2 Certificate of Analysis for Emissions Test Fuels
Fuel ID: CALEV3_10
Page 60
Fuel ID: CALEV3_80
Page 61
Fuel ID: PRLEV3_10
Page 62
Page 63
Page 64
Page 65
Page 66
Page 67
Page 68
Page 69
Page 70
Page 71
Page 72
Page 73
Page 74
Page 75
11.3 Catalyst Aging Test Fuel Properties
Fuel Name --->
ASTM
Method Units
Laboratory --->
Distillation
D86
IBP
F
10%
F
50%
F
90%
F
EP
F
Sulfur
D5453
ppm
RVP
D5191
psi
Lead
D3237
g/gal
Specific Gravity
D4052
Carbon
D5291
%mass
Hydrogen
D5291
%mass
Oxygen, by calculation D4815
%mass
Aromatics
D1319
%vol
Saturates
D1319
%vol
Olefins
D1319
%vol
Phosphorous
D3231
g/gal
Aging Fuel
8/6/2012
Paragon
Aging Fuel
9/17/2012
Paragon
Aging Fuel
10/5/2012
Paragon
97.4
141.8
230.7
330.2
402.6
18.5
6.6
<0.001
0.737
85.85
14.15
0
21.7
76.6
1.7
<0.0002
99.7
143.9
229.8
318.6
401.3
43.0
6.7
<0.001
0.7297
85.6
14.4
0
16.7
80.4
2.9
<0.0002
81.3
103.1
229
338.1
408.4
30.4
12.53
<0.001
0.7366
86.28
13.72
0
25.6
66.9
7.5
<0.0002
Aging Fuel
10/11/2012
Paragon
Aging Fuel
10/18/2012
Paragon
34.4
31.4
0.7356
0.7361
Page 76
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
100
CCC Front Bed
1050
1040
1030
1020
1010
990
1000
980
970
960
950
940
930
920
910
900
890
880
870
860
850
840
830
820
810
800
790
780
770
UBC Front Bed
760
90
80
70
60
50
40
30
20
10
0
CCC Inlet
750
11.4 Exhaust and Catalyst Temperature Histograms for Aging Test
Temperature (°C)
API01 Malibu Catalyst Thermal Exposure During Aging Test
Page 77
100
90
CCC Inlet
80
70
60
50
40
30
20
10
90
CCC Front Bed
80
70
60
50
40
30
20
1050
1040
1030
1020
1010
990
1000
980
970
960
950
940
930
920
910
900
890
880
870
860
850
840
830
820
810
800
790
780
770
0
760
10
750
100
0
Temperature (°C)
API02 Civic Catalyst Thermal Exposure During Aging Test
Page 78
100
90
CCC Inlet
80
70
60
50
40
30
20
10
100
0
CCC Front Bed
80
70
60
50
40
30
20
10
0
100
90
UBC Front Bed
80
70
60
50
40
30
20
1050
1040
1030
1020
1010
990
1000
980
970
960
950
940
930
920
910
900
890
880
870
860
850
840
830
820
810
800
790
780
770
0
760
10
750
90
Temperature (°C)
API03 Sonata Catalyst Thermal Exposure During Aging Test
Page 79
100
90
CCC Inlet
80
70
60
50
40
30
20
10
100
0
90
CCC Front Bed
80
70
60
50
40
30
20
10
0
100
90
UBC Front Bed
80
70
60
50
40
30
20
1050
1040
1030
1020
1010
990
1000
980
970
960
950
940
930
920
910
900
890
880
870
860
850
840
830
820
810
800
790
780
770
760
0
750
10
Temperature (°C)
API04 Focus Catalyst Thermal Exposure During Aging Test
Job 6525
Page 80
100
90
CCC Inlet
80
70
60
50
40
30
20
90
CCC Front Bed
80
70
60
50
40
30
20
10
100
0
90
80
UBC Front Bed
70
60
50
40
30
20
1050
1040
1030
1020
1010
990
1000
980
970
960
950
940
930
920
910
900
890
880
870
860
850
840
830
820
810
800
790
780
770
0
760
10
750
10
100
0
Temperature (°C)
API05 A3 Catalyst Thermal Exposure During Aging Test
Page 81
API06 Camry Catalyst Thermal Exposure During Aging Test
Page 82
11.5 Dynamometer Equivalent Test Weights and Road Load Coefficients
Vehicle
API01
API02
API03
API04
API05
API06
Model
Malibu
Civic
Sonata
Focus
A3
Camry
ETW (lb)
3875
3125
3500
3250
3750
3750
Target Coefficients
2
A (lb)
B (lb/mph) C (lb/mph )
35.30
0.3548
0.01960
22.65
0.2074
0.01629
29.45
0.5673
0.01010
31.88
0.2815
0.01943
32.00
0.2700
0.02000
29.52
0.1087
0.01925
Dyno Set Coefficients
2
A (lb)
B (lb/mph) C (lb/mph )
18.41
9.16
8.20
12.38
13.09
14.10
0.0604
0.1326
0.2605
0.2474
0.2284
-0.0855
0.02085
0.01589
0.01249
0.01898
0.01893
0.02015
11.6 Manufacturer Recommended Motor Oils
Vehicle
Viscosity
Comment
2009 Chevrolet Malibu 5W-30
Synthetic oil required, to meet GM6094 spec
2012 Honda Civic EX
0W-20
This viscosity only available as a synthetic oil
2012 Hyundai Sonata
5W-20
Synthetic or conventional oil
2012 Ford Focus
5W-20
Synthetic oil required
2012 Audi A3
5W-40
Only synthetic oils currently meet VW 502 00 spec
2012 Toyota Camry
0W-20
This viscosity only available as a synthetic oil
Mobil 1 Synthetic Oil was used for all test vehicles
Page 83
11.7 Catalyst Warm-Up and NOx Light-Off for Each Vehicle, Reversibility Sequence, FTP75
Vehicle API01 - Malibu
Page 84
Vehicle API02 - Civic
Page 85
Vehicle API03 - Sonata
Page 86
Vehicle API04 – Focus – Repeat Sequence
Page 87
Vehicle API05 – A3
Page 88
Vehicle API06 – Camry
Page 89
11.8 Raw Exhaust Emissions and Catalyst Conversion Efficiency
Page 90
Vehicle API01 - Malibu
■ 10ppm Sulfur Fuel
(Baseline)
■ 80ppm Sulfur Fuel ■ 10ppm Sulfur Fuel (Reversibility)
Page 91
Vehicle API02 - Civic
(Baseline)
Page 92
Vehicle API03 - Sonata
(Baseline)
Page 93
Vehicle API04 – Focus – Initial Sequence
(Baseline)
Page 94
Vehicle API04 – Focus – Repeat Sequence
(Baseline)
Page 95
Vehicle API05 – A3
(Baseline)
Page 96
Vehicle API06 - Camry
(Baseline)
Page 97
11.9 Soot, Particle Number and Size Distribution Reports
Page 98
Particle Number and Particle Size Distribution Report - FTP75 Drive Cycle
TestID:
2109191
CarID:
API01
Driver:
MWEDDINGTON
Date:
1/30/2013 11:38
Fuel:
CALEV3_10
Results Summary
Phase II
2.18E+10
4.59E+11
0.034
3.85
6.20
8.40E+10
1.77E+12
0.13
-
Phase III Weighted
1.13E+11 1.02E+12
5.44E+11 1.54E+12
0.057
0.333
3.59
5.77
4.07E+11
1.95E+12
0.21
-
Phase I Phase II Phase III
CPC Max Raw Particle Concentration (#/cc)
1.30E+04 5.32E+01 5.70E+02
CPC Max Corrected Particle concentration (#/cc) 6.58E+06 2.68E+04 2.87E+05
TSI First Stage Dilution Factor Avg
70.09
70.09
70.09
TSI Second Stage Dilution Factor Avg
6.00
5.99
5.99
TSI Correction Factor Avg
5.04E+02 5.04E+02 5.04E+02
CVS Flow Avg (scfm)
344.92
344.84
344.58
MSS Dilution Ratio Avg
1.00
1.00
1.00
Temp of Rotating Disk Diluter Avg (deg C)
154.27
154.27
154.31
Temp of Evaporator Tube Avg (deg C)
300.00
300.00
300.00
Instantaneous Particle Number over FTP75 Phase I
1.6E+12
CPC_PN (#)
60
1.2E+12
Speed (mph)
50
1E+12
40
8E+11
30
6E+11
20
4E+11
10
2E+11
0
0
0
100
200
300
400
500
Time (s)
Particle Size Distribution at Peak Emission Rate
Soot Concentration over FTP75 Phase I
35000
3.5
70
MSS_CC (mg/m3)
3
25000
20000
15000
10000
5000
0
60
Speed (mph)
2.5
50
2
40
1.5
30
1
20
0.5
10
0
10
100
Particle Diameter (nm)
Speed (mph)
30000
Soot Concentration (mg/m3)
Raw Concentration [dN/dlogDp, #/cc]
70
EEPS_PN (#)
1.4E+12
Speed (mph)
Phase I
4.67E+12
5.55E+12
1.442
3.61
5.82
1.69E+13
2.01E+13
5.21
50.84
Particle Number
CPC Particle Number (#/mi)
EEPS Particle Number (#/mi)
MSS Soot Mass (mg/mi)
Distance (mi)
Distance (km)
CPC Particle Number (#)
EEPS Particle Number (#)
MSS Soot Mass (mg)
Median Particle Dia at Peak Emission (nm)
0
0
100
200
300
400
500
Time (s)
TestID:
2109191
CarID:
API01
Driver:
MWEDDINGTON
Date:
1/30/2013 11:38
Fuel:
CALEV3_10
Page 99
TestID:
2109309
CarID:
API01
Driver:
MWEDDINGTON
Date:
2/5/2013 10:14
Fuel:
CALEV3_80
Results Summary
Phase I
1.49E+04
CPC Max Corrected Particle concentration (#/cc) 7.51E+06
70.10
6.00
5.04E+02
CVS Flow Avg (scfm)
347.12
1.00
154.22
300.00
Phase II
1.47E+02
7.42E+04
70.10
6.00
5.04E+02
347.13
1.00
154.22
300.00
Phase III
6.49E+02
3.27E+05
70.10
5.99
5.04E+02
346.84
1.00
154.25
300.00
1.8E+12
6E+11
10
2E+11
0
0
0
100
200
300
400
500
Time (s)
10000
20
4E+11
3.5
15000
30
8E+11
40000
20000
40
1E+12
4
25000
50
Speed (mph)
1.2E+12
30000
CPC_PN (#)
1.4E+12
45000
35000
60
EEPS_PN (#)
1.6E+12
60
MSS_CC (mg/m3)
50
Speed (mph)
3
40
2.5
2
30
1.5
20
1
10
0.5
5000
0
0
10
100
Speed (mph)
Phase III Weighted
1.67E+11 1.18E+12
3.35E+11 1.60E+12
0.099
0.391
3.60
5.79
5.99E+11
1.21E+12
0.36
-
Speed (mph)
Phase II
3.67E+10
3.59E+11
0.072
3.88
6.25
1.43E+11
1.39E+12
0.28
-
Particle Number
Phase I
5.39E+12
6.38E+12
1.574
3.61
5.80
1.94E+13
2.30E+13
5.67
52.34
Distance (mi)
Distance (km)
MSS Soot Mass (mg)
0
0
100
200
300
400
500
Time (s)
TestID:
2109309
CarID:
API01
Driver:
MWEDDINGTON
Date:
2/5/2013 10:14
Fuel:
CALEV3_80
Page 100
TestID:
2109229
CarID:
API02
Driver:
MWEDDINGTON
Date:
1/31/2013 12:25
Fuel:
CALEV3_10
Results Summary
Phase II
3.43E+10
4.10E+11
0.036
3.86
6.21
1.32E+11
1.58E+12
0.14
-
Phase III Weighted
6.22E+10 6.97E+11
6.28E+11 1.16E+12
0.029
0.237
3.59
5.78
2.24E+11
2.26E+12
0.10
-
7.71E+03 2.93E+01 6.55E+01
70.10
70.10
70.10
6.00
5.99
5.99
5.04E+02 5.04E+02 5.04E+02
CVS Flow Avg (scfm)
347.99
348.30
347.81
1.00
1.00
1.00
154.12
154.13
154.18
300.00
300.00
300.00
9E+11
7E+11
CPC_PN (#)
60
Speed (mph)
50
6E+11
5E+11
40
4E+11
30
3E+11
20
2E+11
10
1E+11
0
0
0
100
200
300
400
500
Time (s)
25000
3
70
MSS_CC (mg/m3)
15000
10000
5000
0
2.5
60
Speed (mph)
50
2
40
1.5
30
1
20
0.5
10
0
10
100
Speed (mph)
20000
70
EEPS_PN (#)
8E+11
Speed (mph)
Phase I
3.18E+12
3.71E+12
1.010
3.62
5.82
1.15E+13
1.34E+13
3.66
55.36
Particle Number
Distance (mi)
Distance (km)
MSS Soot Mass (mg)
0
0
100
200
300
400
500
Time (s)
TestID:
2109229
CarID:
API02
Driver:
MWEDDINGTON
Date:
1/31/2013 12:25
Fuel:
CALEV3_10
Page 101
TestID:
2109346
CarID:
API02
Driver:
MWEDDINGTON
Date:
2/6/2013 9:09
Fuel:
CALEV3_80
Results Summary
Phase III Weighted
9.79E+10 7.75E+11
5.60E+11 1.59E+12
0.036
0.300
3.59
5.79
3.52E+11
2.01E+12
0.13
-
Phase I
6.55E+03
70.09
6.00
5.04E+02
CVS Flow Avg (scfm)
345.40
1.00
154.31
300.00
Phase II
1.41E+03
7.13E+05
70.09
5.99
5.04E+02
345.76
1.00
154.29
300.00
Phase III
8.76E+02
4.42E+05
70.09
6.00
5.04E+02
345.37
1.00
154.31
300.00
9E+11
CPC_PN (#)
7E+11
50
Speed (mph)
6E+11
40
5E+11
30
4E+11
3E+11
20
2E+11
10
1E+11
0
0
0
100
200
300
400
500
Time (s)
20000
3.5
60
MSS_CC (mg/m3)
3
16000
14000
12000
10000
8000
6000
4000
2000
50
Speed (mph)
2.5
40
2
30
1.5
20
1
10
0.5
0
0
10
100
Speed (mph)
18000
60
EEPS_PN (#)
8E+11
Speed (mph)
Phase II
1.12E+11
9.54E+11
0.052
3.87
6.23
4.32E+11
3.69E+12
0.20
-
Particle Number
Phase I
3.33E+12
4.52E+12
1.266
3.61
5.81
1.20E+13
1.63E+13
4.57
54.90
Distance (mi)
Distance (km)
MSS Soot Mass (mg)
0
0
100
200
300
400
500
Time (s)
TestID:
2109346
CarID:
API02
Driver:
MWEDDINGTON
Date:
2/6/2013 9:09
Fuel:
CALEV3_80
Page 102
TestID:
2109383
CarID:
API03
Driver:
MWEDDINGTON
Date:
2/7/2013 13:20
Fuel:
CALEV3_10
Results Summary
Phase III Weighted
1.24E+12 5.64E+12
5.84E+11 6.00E+12
0.423
3.471
3.58
5.76
4.42E+12
2.09E+12
1.51
-
Phase I
1.36E+04
70.09
6.00
5.04E+02
CVS Flow Avg (scfm)
348.37
1.00
154.13
300.00
Phase II
2.00E+03
1.01E+06
70.09
6.00
5.04E+02
348.62
1.00
154.14
300.00
Phase III
8.01E+02
4.03E+05
70.09
5.99
5.04E+02
348.03
1.00
154.15
300.00
2.5E+12
CPC_PN (#)
2E+12
50
Speed (mph)
40
1.5E+12
30
1E+12
20
5E+11
10
0
0
0
100
200
300
400
500
Time (s)
70000
12
60
MSS_CC (mg/m3)
50000
40000
30000
20000
10000
0
10
50
Speed (mph)
8
40
6
30
4
20
2
10
0
10
100
Speed (mph)
60000
60
EEPS_PN (#)
Speed (mph)
Phase II
2.97E+12
2.20E+12
1.369
3.87
6.23
1.15E+13
8.50E+12
5.30
-
Particle Number
Phase I
1.81E+13
2.27E+13
12.770
3.60
5.79
6.52E+13
8.17E+13
45.93
70.94
Distance (mi)
Distance (km)
MSS Soot Mass (mg)
0
0
100
200
300
400
500
Time (s)
TestID:
2109383
CarID:
API03
Driver:
MWEDDINGTON
Date:
2/7/2013 13:20
Fuel:
CALEV3_10
Page 103
TestID:
2109500
CarID:
API03
Driver:
MWEDDINGTON
Date:
2/14/2013 8:31
Fuel:
CALEV3_80
Results Summary
Phase III Weighted
1.92E+12 6.57E+12
1.63E+12 7.49E+12
0.738
4.066
3.60
5.79
6.89E+12
5.85E+12
2.65
-
Phase I
1.46E+04
70.09
6.00
5.04E+02
CVS Flow Avg (scfm)
346.99
1.00
154.04
300.00
Phase II
2.12E+03
1.07E+06
70.09
6.00
5.04E+02
346.71
1.00
154.06
300.00
Phase III
1.14E+03
5.74E+05
70.09
6.00
5.04E+02
346.68
1.00
154.08
300.00
2.5E+12
CPC_PN (#)
2E+12
50
Speed (mph)
40
1.5E+12
30
1E+12
20
5E+11
10
0
0
0
100
200
300
400
500
Time (s)
70000
12
60
MSS_CC (mg/m3)
50000
40000
30000
20000
10000
0
10
50
Speed (mph)
8
40
6
30
4
20
2
10
0
10
100
Speed (mph)
60000
60
EEPS_PN (#)
Speed (mph)
Phase II
4.02E+12
3.49E+12
1.973
3.91
6.30
1.57E+13
1.37E+13
7.72
-
Particle Number
Phase I
1.91E+13
2.53E+13
13.731
3.62
5.83
6.92E+13
9.15E+13
49.71
72.11
Distance (mi)
Distance (km)
MSS Soot Mass (mg)
0
0
100
200
300
400
500
Time (s)
TestID:
2109500
CarID:
API03
Driver:
MWEDDINGTON
Date:
2/14/2013 8:31
Fuel:
CALEV3_80
Page 104
TestID:
2110638
CarID:
API04
Driver:
MWEDDINGTON
Date:
5/13/2013 12:34
Fuel:
CALEV3_10
Results Summary
Phase III Weighted
2.42E+12 2.85E+12
2.31E+12 3.07E+12
0.660
0.887
3.60
5.79
8.72E+12
8.32E+12
2.38
-
4.64E+03 1.03E+03 2.25E+03
70.09
70.09
70.10
5.99
5.99
5.99
5.04E+02 5.04E+02 5.04E+02
CVS Flow Avg (scfm)
347.51
347.46
347.11
1.00
1.00
1.00
154.12
154.13
154.16
300.00
300.00
300.00
5E+11
4E+11
3.5E+11
2E+11
30
20
1E+11
5E+10
10
0
300
400
500
70
MSS_CC (mg/m3)
60
Speed (mph)
0.7
50
0.6
0.5
40
0.4
30
0.3
20
0.2
0.1
0
0
200
2000
100
100
Time (s)
12000
10
0
0
0.8
4000
50
1.5E+11
0.9
6000
60
Speed (mph)
40
8000
CPC_PN (#)
3E+11
2.5E+11
14000
10000
70
EEPS_PN (#)
4.5E+11
Speed (mph)
Phase II
1.51E+12
1.69E+12
0.435
3.85
6.20
5.80E+12
6.52E+12
1.67
-
Speed (mph)
Phase I
6.79E+12
7.51E+12
2.317
3.58
5.76
2.43E+13
2.69E+13
8.29
44.91
Particle Number
Distance (mi)
Distance (km)
MSS Soot Mass (mg)
10
0
0
100
200
300
400
500
Time (s)
TestID:
2110638
CarID:
API04
Driver:
MWEDDINGTON
Date:
5/13/2013 12:34
Fuel:
CALEV3_10
Page 105
TestID:
2110675
CarID:
API04
Driver:
MWEDDINGTON
Date:
5/16/2013 11:59
Fuel:
CALEV3_80
Results Summary
Phase I
5.41E+03
70.09
5.99
5.04E+02
CVS Flow Avg (scfm)
344.11
1.00
154.12
300.00
Phase II
7.96E+02
4.01E+05
70.09
5.99
5.04E+02
344.11
1.00
154.14
300.00
Phase III
1.98E+03
9.97E+05
70.09
6.00
5.04E+02
343.76
1.00
154.15
300.00
6E+11
4E+11
40
3E+11
30
2E+11
20
1E+11
10
0
200
300
400
500
12000
2000
100
Time (s)
1.6
4000
0
0
1.8
6000
50
Speed (mph)
8000
CPC_PN (#)
5E+11
14000
10000
60
EEPS_PN (#)
60
MSS_CC (mg/m3)
50
Speed (mph)
1.4
1.2
40
1
30
0.8
0.6
20
0.4
10
0.2
0
0
10
100
Speed (mph)
Phase III Weighted
2.36E+12 2.84E+12
3.54E+12 6.06E+12
0.568
0.783
3.56
5.73
8.40E+12
1.26E+13
2.02
-
Speed (mph)
Phase II
1.55E+12
5.41E+12
0.407
3.79
6.11
5.89E+12
2.05E+13
1.54
-
Particle Number
Phase I
6.63E+12
1.10E+13
1.995
3.58
5.76
2.37E+13
3.93E+13
7.14
51.15
Distance (mi)
Distance (km)
MSS Soot Mass (mg)
0
0
100
200
300
400
500
Time (s)
TestID:
2110675
CarID:
API04
Driver:
MWEDDINGTON
Date:
5/16/2013 11:59
Fuel:
CALEV3_80
Page 106
TestID:
2110113
CarID:
API05
Driver:
MWEDDINGTON
Date:
3/27/2013 7:27
Fuel:
PRLEV3_10
Results Summary
Phase II
2.85E+12
5.07E+12
0.702
3.86
6.21
1.10E+13
1.96E+13
2.71
-
Phase III Weighted
5.20E+12 4.34E+12
5.91E+12 6.30E+12
2.026
1.277
3.59
5.78
1.87E+13
2.12E+13
7.28
-
8.55E+03 3.69E+03 8.21E+03
70.09
70.09
70.09
6.00
5.99
5.99
5.04E+02 5.04E+02 5.04E+02
CVS Flow Avg (scfm)
346.92
346.91
346.70
1.00
1.00
1.00
154.14
154.11
154.16
300.00
300.00
300.00
1.2E+12
1E+12
CPC_PN (#)
60
Speed (mph)
50
8E+11
40
6E+11
30
4E+11
20
2E+11
10
0
0
0
100
200
300
400
500
Time (s)
30000
3
70
MSS_CC (mg/m3)
20000
15000
10000
5000
0
2.5
60
Speed (mph)
50
2
40
1.5
30
1
20
0.5
10
0
10
100
Speed (mph)
25000
70
EEPS_PN (#)
Speed (mph)
Phase I
6.90E+12
9.92E+12
1.720
3.59
5.78
2.48E+13
3.56E+13
6.18
52.05
Particle Number
Distance (mi)
Distance (km)
MSS Soot Mass (mg)
0
0
100
200
300
400
500
Time (s)
TestID:
2110113
CarID:
API05
Driver:
MWEDDINGTON
Date:
3/27/2013 7:27
Fuel:
PRLEV3_10
Page 107
TestID:
2110152
CarID:
API05
Driver:
MWEDDINGTON
Date:
4/1/2013 12:59
Fuel:
PRLEV3_80
Results Summary
Phase III Weighted
4.16E+12 4.24E+12
4.83E+12 5.11E+12
1.469
1.306
3.58
5.76
1.49E+13
1.73E+13
5.26
-
1.64E+04 2.81E+03 5.02E+03
70.09
70.09
70.09
6.00
5.99
5.99
5.04E+02 5.04E+02 5.04E+02
CVS Flow Avg (scfm)
346.92
347.18
346.63
1.00
1.00
1.00
154.13
154.13
154.18
300.00
300.00
300.00
2.5E+12
2E+12
1E+12
30
20
10
0
0
0
100
200
300
10000
400
500
Time (s)
20000
50
40
5
4.5
30000
60
Speed (mph)
1.5E+12
40000
CPC_PN (#)
5E+11
60000
50000
70
EEPS_PN (#)
70
MSS_CC (mg/m3)
60
Speed (mph)
4
3.5
50
3
2.5
40
2
30
1.5
20
1
10
0.5
0
0
10
100
Speed (mph)
Phase II
2.51E+12
2.76E+12
0.623
3.86
6.21
9.68E+12
1.07E+13
2.40
-
Speed (mph)
Phase I
8.70E+12
1.14E+13
2.798
3.59
5.77
3.12E+13
4.08E+13
10.04
56.13
Particle Number
Distance (mi)
Distance (km)
MSS Soot Mass (mg)
0
0
100
200
300
400
500
Time (s)
TestID:
2110152
CarID:
API05
Driver:
MWEDDINGTON
Date:
4/1/2013 12:59
Fuel:
PRLEV3_80
Page 108
TestID:
2109476
CarID:
API06
Driver:
MWEDDINGTON
Date:
2/13/2013 9:54
Fuel:
CALEV3_10
Results Summary
Phase III Weighted
5.40E+10 2.55E+11
2.29E+11 7.04E+11
0.063
0.120
3.58
5.77
1.93E+11
8.19E+11
0.23
-
Phase I
3.24E+03
70.09
5.99
5.04E+02
CVS Flow Avg (scfm)
344.85
1.00
154.06
300.00
Phase II
2.01E+01
1.01E+04
70.09
5.99
5.04E+02
345.07
1.00
154.03
300.00
Phase III
2.47E+02
1.25E+05
70.09
5.99
5.04E+02
345.23
1.00
154.09
300.00
3.5E+11
CPC_PN (#)
50
Speed (mph)
2.5E+11
40
2E+11
30
1.5E+11
20
1E+11
10
5E+10
0
0
0
100
200
300
400
500
Time (s)
10000
0.35
60
MSS_CC (mg/m3)
0.3
8000
7000
6000
5000
4000
3000
2000
1000
50
Speed (mph)
0.25
40
0.2
30
0.15
20
0.1
10
0.05
0
0
10
100
Speed (mph)
9000
60
EEPS_PN (#)
3E+11
Speed (mph)
Phase II
4.43E+10
6.97E+11
0.096
3.84
6.17
1.70E+11
2.67E+12
0.37
-
Particle Number
Phase I
1.04E+12
1.35E+12
0.255
3.60
5.79
3.76E+12
4.86E+12
0.92
37.06
Distance (mi)
Distance (km)
MSS Soot Mass (mg)
0
0
100
200
300
400
500
Time (s)
TestID:
2109476
CarID:
API06
Driver:
MWEDDINGTON
Date:
2/13/2013 9:54
Fuel:
CALEV3_10
Page 109
TestID:
2109556
CarID:
API06
Driver:
MWEDDINGTON
Date:
2/19/2013 8:07
Fuel:
CALEV3_80
Results Summary
Phase III Weighted
6.17E+10 2.33E+11
2.56E+11 7.39E+11
0.038
0.079
3.60
5.79
2.22E+11
9.19E+11
0.14
-
Phase I
2.57E+03
70.09
6.00
5.04E+02
CVS Flow Avg (scfm)
349.13
1.00
154.14
300.00
Phase II
1.62E+01
8.15E+03
70.09
6.00
5.04E+02
349.23
1.00
154.10
300.00
Phase III
6.02E+02
3.04E+05
70.09
6.00
5.04E+02
348.93
1.00
154.13
300.00
3E+11
CPC_PN (#)
2.5E+11
50
Speed (mph)
2E+11
40
1.5E+11
30
1E+11
20
5E+10
10
0
0
0
100
200
300
400
500
Time (s)
7000
0.35
60
MSS_CC (mg/m3)
0.3
5000
4000
3000
2000
1000
50
Speed (mph)
0.25
40
0.2
30
0.15
20
0.1
10
0.05
0
0
10
100
Speed (mph)
6000
60
EEPS_PN (#)
Speed (mph)
Phase II
1.63E+10
5.84E+11
0.047
3.87
6.24
6.32E+10
2.26E+12
0.18
-
Particle Number
Phase I
1.00E+12
1.77E+12
0.211
3.60
5.79
3.60E+12
6.36E+12
0.76
43.99
Distance (mi)
Distance (km)
MSS Soot Mass (mg)
0
0
100
200
300
400
500
Time (s)
TestID:
2109556
CarID:
API06
Driver:
MWEDDINGTON
Date:
2/19/2013 8:07
Fuel:
CALEV3_80
Page 110

reversibility of gasoline sulfur effects

Transcription

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