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Journal ArticleDOI

A comparison of a mini-PEMS and a 1065 compliant PEMS for on-road gaseous and particulate emissions from a light duty diesel truck.

01 Nov 2018-Science of The Total Environment (Sci Total Environ)-pp 364-376

TL;DR: There could be applications for the NCEM or other mini-PEMS for applications such as identification of potential issues by regulatory agencies, manufacturer evaluation and validation of emissions under in-use conditions, and potential use in inspection and maintenance (I/M) programs, especially for heavy-duty vehicles.

AbstractThe primary goal of this study was to compare emissions measurements between a 1065 compliant PEMS, and the NTK Compact Emissions Meter (NCEM) capable of measuring NOx, PM, and solid PN. Both units were equipped on a light-duty diesel truck and tested over local, highway, and downtown driving routes. The results indicate that the NOx measurements for the NCEM were within approximately ±10% of those the 1065 compliant PEMS, which suggests that the NCEM could be used as a screening tool for NOx emissions. The NCEM showed larger differences for PM emissions on an absolute level, but this was at PM levels well below the 1 mg/mi level. The NCEM differences ranged from −2% to +26% if the comparisons are based on a percentage of the 1.0 mg/mi standard. Larger differences were also seen for PN emissions, with the NCEM measuring higher PN emissions, which can primarily be attributed to a zero current offset that we observed for the NCEM, which has been subsequently improved in the latest generation of the NCEM system. The comparisons between the 1065 compliant PEMS and the NCEM suggest that there could be applications for the NCEM or other mini-PEMS for applications such as identification of potential issues by regulatory agencies, manufacturer evaluation and validation of emissions under in-use conditions, and potential use in inspection and maintenance (I/M) programs, especially for heavy-duty vehicles.

Summary (3 min read)

1. Introduction

  • Portable Emissions Measurement Systems (PEMS) are tools that are designed to measure vehicle/truck emissions while operating on the road.
  • PEMS serve an important role in helping to better understand and characterize the differences between laboratory certification and other testing and real-world emissions.
  • As in-use emissions testing has advanced, emissions data has continued to show the importance of measuring emissions in-use to fully understand the range of emissions emitted by vehicles under different operating conditions.
  • Given the complexity and cost of 1065 compliant PEMS, there is a growing interest in the development ofmini-PEMS that are not targeted at compliance with 1065 specifications, but still provide reliable emissions measurements, and are easy to deploy and less expensive.

2.1. Test vehicle, engine, and fuel

  • The test vehicle is a model year 2012 Chevrolet Silverado 2500HD.
  • This vehicle is equipped with an engine family CGMXD06.6355 diesel engine.
  • The engine is 6.6-liter, eight cylinders, turbocharged, direct injection, and common-rail engine configuration with a six-speed automatic transmission.
  • It should be noted that the vehicle was filled up several times at the same retail fueling station.
  • Since the properties of in-use California ultralow sulfur diesel are tightly controlled to provide comparable emissions, the use of diesel fuel from different fill ups is expected to have minimal impact on the emissions results.

2.2. Test cycles

  • The vehicle was tested over a period of 2 days using three different driving routes designed to represent local, highway, and LA downtown driving conditions.
  • The characteristics of these three different cycles are shown in Table 1, alongwith the details for the FTP test for comparison.
  • The local route is used to simulate the local driving and has a similar driving pattern to FTP driving cycle.
  • The highway route started at UCR and went to the main campus of the University of Southern California.
  • The total distance of this route was 63.6 mi.

2.3. Instruments

  • The AVL PM PEMS measurement system selected is AVL's 483 micro soot sensor (MSS) in conjunction with their gravimetric filter module (GFM) option.
  • The NCEM uses direct measurement sensors rather than dilution sampling.
  • It can be poweredby aDC12/24 V vehicle battery and draws b10 Amp to operate.
  • In these cases the sensitivity to NO2 could be slightly lower than the sensitivity to NO.

TK AVL MSS AVL PM NTK AVL

  • The PM/PN sensor is based on the Pegasor PPS-M technology, where particles are charged in a corona discharge, such that the totalmeasured charge is proportional to the particle surface area, as shown in Fig. 2 (Lanki et al., 2011; Ntziachristos et al., 2011; Ntziachristos et al., 2013; Rostedt et al. 2017).
  • Todetermine PN, the sensor is calibrated against a TSI scanning mobility particle sizer (SMPS).
  • Both the PM and PN calibrations are performed with a soot generator that provides soot particles with a unimodal distributionwith peak concentration around 75 nm.
  • Simulations using a range of possible diesel particle size distributions, however, have shown that the maximum theoretical error is 23% when using surface area as a proxy for number and 39%when using surface area as a proxy for soot mass, although the actual error is expected to bemuch less than these values (Ntziachristos et al., 2012).
  • A Semtech 4-inch Exhaust Flow Measurement (EFM) system was used by both systems for the measurement of the exhaust flow to provide integrated mass emissions as well as second by second data for each pollutant.

2.4. Measurement protocols

  • The experimental set up for study is shown in the Fig.
  • This includes the NCEM, AVL gaseous M.O.V.E. system, AVL PM system, and the AVL PN PEMS iS.
  • The power system for the set up included a Yamaha gasoline generator model EF2800i, which has two 120 V AC plugs with 20A maximum current each, a CHARGEMASTER 12 V power converter to power the AVL GasM.O.V.E system, and a Xantrex sinewave inverter powered through a twin 12 V battery pack to power the EFM and the computers.
  • The purpose of the 12 V batteries were to support as a backup power source, whichwas necessarywhen switching frombuilding power to the generator power, or when powering down the generator to add more fuel.
  • The NCEM was controlled through the screen of the unit with the data logged to a flash drive.

3.1. NOx emissions

  • The NOx emissions results for all the testing routes are shown below in Table 2.
  • The NCEM did not show a consistent bias compared to the AVL M.O.V.E system, with the NCEM reading higher for some test routes and lower for others.
  • The 25 and 75 percentile points are provided in Table 3,which are the points below which 25% and 75% of the measurements fall for both instruments.
  • The NOx emissions can also be compared back to early comparisons between 1065 compliant PEMS and CVS reference methods conducted as part of the Measurement Allowance program (Johnson et al., 2009, 2011a).
  • Following the repairs, the vehicle was tested again over the FTP cycle on a chassis dynamometer, and NOx emission levels were found to be below the 0.2 g/mi NOx emission standard.

3.2. PM emissions

  • The test vehiclewas equippedwith a DPF, so the PMemissions levels were generally low.
  • This suggests a possible PM physical characteristic change between in-town driving and cruise conditions that may have caused the NCEM to report differently.

3.3. PN emissions

  • For the AVL PN PEMS, the PN emissions were typically 93% below the PN standard.
  • The NCEM also measures particles down to ~10 nm (Amanatidis et al., 2017), as opposed to the PN PEMS that has a 23 nm size cut off, which could contribute to higher PNmeasurements for the NCEM.
  • In other work, Tikkanen et al. (2013) found the PPS reported 80% higher PN than an APC for a heavy-duty engine and somewhat higher PN emissions for a passenger car, but lower PN emissions than an APC during a regeneration due to desorption from the CVS and for a Euro 4 diesel vehicle during high speed portions of the testing.

4. Conclusions

  • The primary goal of this study was to compare emissions measurements between a 1065 compliant AVL M.O.V.E.S. PEMS, and a current generation mini-PEMS capable of measuring NOx, PM, and solid PN.
  • The NCEM showed larger differences for PM emissions on an absolute level, but this was at PM levels well below the 1 mg/mi level.
  • While the ECM data was not collected with the NCEM used in this study, the current version of the NCEM does collect ECM data that could be utilized for determining the exhaust flow rate.
  • The comparisons between the 1065 compliant PEMS and the NCEM suggest that there could be applications for the NCEM or other miniPEMS in areas where larger data sets of emissions data, or where the cost of full laboratory or 1065 compliant PEMS testing is prohibitive.
  • As recentfindings have suggested that it is important tomonitor vehicle emissions under a much wider range of conditions than can be duplicated in the laboratory, the NCEM could play a role in allowing for the testing of more vehicles under a broader range of conditions.

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UC Riverside
2018 Publications
Title
A comparison of a mini-PEMS and a 1065 compliant PEMS for on-road gaseous and
particulate emissions from a light duty diesel truck
Permalink
https://escholarship.org/uc/item/5rv097nn
Journal
Science of The Total Environment, 640-641
ISSN
00489697
Authors
Yang, Jiacheng
Durbin, Thomas D
Jiang, Yu
et al.
Publication Date
2018-11-01
DOI
10.1016/j.scitotenv.2018.04.383
Peer reviewed
eScholarship.org Powered by the California Digital Library
University of California

A comparison of a mini-PEMS and a 1065 compliant PEMS for on-road
gaseous and particulate emissions from a light duty diesel truck
Jiacheng Yang
a
,ThomasD.Durbin
a
, Yu Jiang
a
, Takeshi Tange
b
,GeorgiosKaravalakis
a
,
David R. Cocker III
a
,KentC.Johnson
a,
a
Bourns College of Engineering Center for Environmental Research and Technology, University of California, Riverside, CA, USA, 92521
b
NGK Spark Plug Co., Ltd., 14-18 Takatsuji-cho, Mizuho-ku, Nagoya, Japan
HIGHLIGHTS
Emissions Measure ment Comparison
between a fully 1065- PEMS and a
mini-PEMS capable of measuring NOx,
PM, and solid PN.
NOx measurements for the compact
PEMS were within approximately ±10%
of those the full 1065 compliance PEMS
system.
The mini-PEMS showed larger absolute
differences for PM but differences were
3% to +30% of 1 mg/mi certication level.
Larger differences were seen for PN,
which was attributed to a zero current
offset for this older model mini-PEMS.
Mini-PEMS could be used for regulatory
and manufacturer compliance evaluation
and validation, and I/M programs.
GRAPHICAL ABSTRACT
abstractarticle info
Article history:
Received 12 May 2017
Received in revised form 5 March 2018
Accepted 28 April 2018
Available online 31 May 2018
The primary goal of this study was to compare emissions measurements between a 1065 compliant PEMS, and the
NTK Compact Emissions Meter (NCEM) capable of measuring NOx, PM, and solid PN. Both units were equipped on
a light-duty diesel truck and tested over local, highway, and downtown driving routes. The results indicate that the
NOx measurements for the NCEM were within approximately ±10% of those the 1065 compliant PEMS, which
suggests that the NCEM could be used as a screening tool for NOx emissions. The NCEM showed larger differences
for PM emissions on an absolute level, but this was at PM levels well below the 1 mg/mi level. The NCEM differ-
ences ranged from 2% to +26% if the comparisons are based on a percentage of the 1.0 mg/mi standard. Larger
differences were also seen for PN emissions, with the NCEM measuring higher PN emissions, which can primarily
be attributed to a zero current offset that we observed for the NCEM, which has beensubsequently improved in the
latest generation of the NCEM system. The comparisons between the 1065 compliant PEMS and the NCEM suggest
that there could be applications for the NCEM or other mini-PEMS for applications such as identication of poten-
tial issues by regulatory agencies, manufacturer evaluation and validation of emissions under in-use conditions,
and potential use in inspection and maintenance (I/M) programs, especially for heavy-duty vehicles.
© 2018 Published by Elsevier B.V.
Keywords:
NO
x
emission
Particulate mass
Particulate number
PEMS
Light duty diesel truck
Science of the Total Environment 640641 (2018) 364376
Corresponding author.
E-mail address: kjohnson@cert.ucr.edu (K.C. Johnson).
https://doi.org/10.1016/j.scitotenv.2018.04.383
0048-9697 2018 Published by Elsevier B.V.
Contents lists available at ScienceDirect
Science of the Total Environment
journal homepage: www.elsevier.com/locate/scitotenv

1. Introduction
Portable Emissions Measurement Systems (PEMS) are tools that are
designed to measure vehicle/truck emissions while operating on the
road. The application and technology of PEMS has evolved considerably
over the past 20 years. PEMS serve an important role in helping to better
understand and characterize the differences between laboratory certi-
cation and other testing and real-world emissions. PEMS were incorpo-
rated into the regulatory process as part of the 1998 consent decree in
the United States (U.S.) and the regulations for in-use compliance test-
ing of heavy-duty vehicles within the Not-to-Exceed (NTE) areas of op-
eration that were created as part of these proceedings (Federal Register
2003, 2005; US EPA, 2008). This provided an impetus for the develop-
ment of more commercial PEMS. PEMS have also been used extensively
for measurements of emissions from heavy-duty trucks, light-duty ve-
hicles, and construction equipment (Johnson, 2002; Gautam et al.,
2001; Kishan et al., 2011; Frey et al. 2010; Cao et al., 2016a, b). More re-
cently, PEMS have been incorporated into regulations for Real Driving
Emissions (RDE) testing in Europe (Vlachos et al., 2014).
In the development of specications for in-use compliance testing,
there has been an emphasis on PEMS that can replicate the performance
of laboratory grade equipment to the greatest extent possible. In the U.
S., the Code of Federal Regulations (CFR, 2000) under Title 40 Part 1065
has regulated the design and measurement techniques that can be used
for such instrumentation, as well as the methods and verication pro-
cesses to determine the PEMS unit is valid for the in-use compliance
purposes, such as linearity verication, dew point calibration, etc. (40
CFR 1065). An extensive Measurement Allowance program and other
associated studies were also conducted to evaluate the potential vari-
ance of such PEMS in comparison to more traditional laboratory equip-
ment, and to provide an allowance for such deviations in the regulations
(Boucher et al., 2012; Durbin et al., 2007; Fiestetal.,2008; Johnson et al.,
2008, 2009, 2011a, 2011b; Khalek et al., 2010; Khan et al., 2012; Miller
et al., 2006). PEMS that are 1065 compliant and have been veried in-
clude systems by such major manufacturers as AVL, Horiba, and Sensors
Inc. While such PEMS provide a traceable level of accuracy for regula-
tory purposes, 1065 compliant PEMS units are still somewhat large in
size, relatively expensive, and can be complex to use in terms of setup
and operation.
As in-use emissions testing has advanced, emissions data has contin-
ued to show the importance of measuring emissions in-use to fully un-
derstand the range of emissio ns emitted by ve hicles under different
operating conditions. The complexity of in-use emissions has been put
in the spotlight with some high prole cases where excess emissions
have been identied for vehicles operating differently under in-use vs.
laboratory conditions (Federal Register 2003; Thompson et al., 2014).
It is also known that it is difcult to fully characterize and control emis-
sions under all conditions as part of laboratory based certication test-
ing, given the expense of la boratory testing. These issues have put
greater emphasis on the need to collect in-use emissions measurements
from a wider range of vehicles and operating conditions.
Given the complexity and cost of 1065 compliant PEMS, there is a
growing interest in the development of mini-PEMS that are not targeted
at compliance with 1065 specications, but still provide reliable emis-
sions measurements, and are easy to deploy and less expensive. Mini-
PEMS are simplied versions of the 1065 compliant PEMS discusse d
above. Such PEMS could have a number of applications in that they
could be used to screen larger numbers of vehicles to identify and char-
acterize potential emissions issues. This could be of use to both engine
and vehicle manufacture rs to identify potential issues under real-
world, or to government agencies looking for issues that might require
more extensive investigation as part of enforcement programs. Such
PEMS could also be used for enforcement in applications such as Inspec-
tion and Maintenance (I/M) programs. Some simpler instruments de-
signed to target only a single emissions component are already being
applied in I/M type of applications. Opacity has been used extensively
as a surrogate for particulate matter (PM) emissions in a number of dif-
ferent areas. More recently, the Swiss SR941.242 Regulation in Europe is
requiring biannual testing of off-road diesel machinery equipped with
DPFs for compliance with a particle number (PN) mini-PEMS.
The development of non-1065 compliant mini-PEMS type of sys-
tems that can provide measurements of multiple pollutants has also ex-
panded recently. Maha has developed a PEMS that can measure NOx,
CO
2
, and PM. The company 3DATX has developed their 2nd generation
parSYNC PEMS that includes the real-time measurement of NOx, CO
2
,
and PM mass (Ropkins et al., 2016). Pegasor (Saukko et al., 2016), TSI
Incorporated (2015), Testo, and Emisense (Steppan et al., 2011) have
also developed small measu rement systems or sensors for PEMS for
PM/PN. NGK Spark Plug has also developed a mini-PEMS called the
NTK Compact Emissions Meter (NCEM) (Jiang et al., 2016). The system
can be used to measure particulate matter (PM) and particle number
(PN), nitrogen oxides (NOx), oxygen (O
2
), and air/fuel ratio. While
such low cost mini-PEMS could provide considerably utility in measur-
ing a large number of vehicles under many different operating condi-
tions, it is important to better characterize the accuracy, repeatability,
and robustness of such systems.
The goal of this study was to compare emissions measurements be-
tween a 1065 compliant PEMS, and one of the current generation mini-
PEMS. This included a 1065 compliant AVL M.O.V.E system and a NTK
NCEM system. Both PEMS units were equipped on a light-duty truck
over local, highway, and downtown driving over 2 days. The results in-
dicate that the NOx measurements between a 1065 compliant PEMS
and the mini-PEMS were within approximately ±10%, suggesting the
NTK PEMS could be used as a screening tool for NOx emissions. Larger
differences were found for PM and solid PN measurements that suggest
that additional development of these measurement methods could be
benecial.
2. Materials and methods
2.1. Test vehicle, engine, and fuel
The test vehicle is a model year 2012 Chevrolet Silverado 2500HD
Duramax light duty diesel pickup truck, which is widely available and
used in the U.S. market. This vehicle has 43,140 mi at the start of the
test and GVWR is in the range of 850110,000 lbs. The vehicle is
equipped with advanced after-treatment technologies that have been
implemented in the diesel eet, such as DOC, DPF, and SCR. The vehicle
is certied to U.S. EPA Tier 2 HDV/HD8510 (NOx at 0.8 g/mi and PM at
0.06 g/mi [U.S. EPA, 2016]) and CARB MDV/ULEV (NOx at 0.2 g/mi and
PM at 0.06 g/mi [CARB, 2016]) emissions standards.
This vehicle is equipped with an engine family CGMXD06.6355 die-
sel engine. The engine is 6.6-liter, eight cylinders, turbocharged, direct
injection, and common-rail engine conguration with a six-speed auto-
matic transmission. The engine can deliver 397 hp at 3000 rpm and
765 lb-ft torque at 1600 rpm and has a compression ratio of 16.8:1.
The test fuel of this study was commercially available No. 2 diesel
fuel from a local retail fueling station. It should be noted that the vehicle
Table 1
Summary of trips statistics for different routes and cycles.
Test
routes/cycles
Distance
(mi)
Average
speed (mph)
Maximum
speed (mph)
Number
of stops
Cycle
duration (s)
FTP 11.04 21.2 56.7 23 1874
LA4 7.50 19.6 56.7 18 1372
Local 6.80 16.3 53.6 11 1402
Highway 63.10 34.8 81.4 22 6545
LA
downtown
15.80 15.8 65.6 45 3617
Idle and
creep
1.80 2.5 32.9 18 2624
365J. Yang et al. / Science of the Total Environment 640641 (2018) 364376

was lled up several times at the same retail fueling station. Since the
properties of in-use California ultralow sulfur diesel are tightly con-
trolled to provide comparable emissions, the use of diesel fuel from dif-
feren t ll ups is expected to have minimal impact on the emissions
results.
2.2. Test cycles
The vehicle was tested over a period of 2 days using three different
driving routes designed to represent local, highway, and LA downtown
driving conditions. The characteristics of these three different cycles are
shown in Table 1, along with the details for the FTP test for comparison.
The local route started and ended at the UCR CE-CERT facility in Riv-
erside, and covered a distance of 6.8 mi. The local route was performed
triplicate in order to get repeatable results. The local route is used to
simulate the local driving and has a similar driving pattern to FTP driv-
ing cycle.
Fig. 3. Instrument setup and power supply for on-road PEMS testing.
Fig. 2. NCEM PM and PN measurement design schematic.
Fig. 1. NCEM NOx measurement design schematic.
366 J. Yang et al. / Science of the Total Environment 640641 (2018) 364376

The highway route started at UCR and went to the main campus of
the University of Southern California. The total distance of this route
was 63.6 mi. The highway route includes over 95% highway driving
along Highways I-60, I-10, I-710, and I-110. This route was conducted
as a round trip, going rst from UCR to USC and then back to UCR.
The LA downtown route started and ended at USC main campus on
Jefferson Boulevard. It covered a distance of 15.7 mi. This route is used
to simulate urban driving conditions in downtown LA. This route essen-
tially represents the route that was used to develop the original FTP
cycle. Additional idle and creep driving was also incorporated into this
route. This route was performed twice.
2.3. Instruments
For this study, a commercial available 1065 compliant AVL M.O.V.E
system was utilized (Cao et al., 2016b). The AVL M.O. V.E system in-
clude s gas-phase analyzers for nitrogen oxide (NO) and nitrogen
dioxide (NO
2
), carbon monoxide (CO), carbon dioxide (CO
2
), total hy-
drocarbo n (THC), non-methane hydrocarbon (NMHC), and methane
(CH
4
) and also particulate phase emissions of PM mass, solid PM
mass, and also solid particle number (PN). The AVL M.O.V.E s ystem
measures oxides of nitrogen (NO and NO
2
) by non-dispersive ultravio-
let radiation (NDUV), and then calculates the NOx value based on the
reported NO and NO
2
emissions. The AVL PM PEMS measurement sys-
tem selected is AVL's 483 micro soot sensor (MSS) in conjunction with
their gravimetric lter module (GFM) option. The combined system is
called the AVL 494 PM system. The MSS instrument measures the mod-
ulated laser light absorbed by particles from an acoustical microphone.
Since the MSS only detects elemental carbon, the GFM is included
along with a post processor to allow the soluble organic fraction (SOF)
and sulfate fraction to be estimated, based on a comparison of the
MSS and GFM measurements. The combined MSS + GFM system re-
cently received type approval by EPA as a total PM measurement solu-
tion for in-use testing, thus making it one of the few 1065 compliant
Fig. 4. Vehicle speed based comparisons for NOx emissions for 1 day of testing.
Table 2
Summary of NOx emissions.
Results Start location End location Mini-PEMS 1065 compliance PEMS Mini-PEMS 1065 compliance PEMS
NOx NOx NO NO
2
NOx NOx NO NO
2
NO/NO
2
g/cycle g/mi
Local_1 UCR CECERT UCR CECERT 23.26 25.14 13.39 4.63 3.44 3.72 1.98 0.69 2.89
Local_2 UCR CECERT UCR CECERT 33.19 31.06 14.64 8.64 4.82 4.51 2.12 1.25 1.7
Local_3 UCR CECERT UCR CECERT 34.22 26.85 12.79 7.25 5.06 3.97 1.89 1.07 1.76
Average 4.44 4.07
% difference 9.20%
Highway_1 UCR CECERT USC main campus 137.21 142.99 68.51 38.06 2.17 2.26 1.08 0.6 1.8
Highway_2 USC main campus UCR CECERT 144.14 146.72 69.4 40.43 2.29 2.33 1.1 0.64 1.72
Average 2.23 2.3
% difference 2.90%
LA Downtown_1 USC main campus USC main campus 36.39 35.75 15.39 12.18 2.3 2.26 0.97 0.77 1.26
LA Downtown_2 USC main campus USC main campus 39.03 37.71 16.07 13.1 2.47 2.39 1.02 0.83 1.23
Average 2.39 2.32
% difference 2.70%
Idle and Creep USC main campus USC main campus 10.38 11.45 6.23 1.91 5.76 6.36 3.46 1.06 3.26
% difference 9.40%
Total 457.84 457.68 216.42 126.2 3.54 3.47 1.7 0.86 1.97
These values are the average of all the NOx emissions over all different cycles in g/mi basis.
367J. Yang et al. / Science of the Total Environment 640641 (2018) 364376

Citations
More filters

Journal ArticleDOI
TL;DR: This paper gives an overview of the studies for SPN-PEMS from early 2013 with the first prototypes until the latest testing and improvements in 2019, and addresses measurement uncertainty at the on-road emission results measured with PEMS.
Abstract: Portable emissions measurement systems (PEMS) for gaseous pollutants were firstly introduced in the United States regulation to check the in-use compliance of heavy-duty engines, avoiding the high costs of removing the engine and testing it on a dynamometer in the laboratory. In Europe, the in-service conformity of heavy-duty engines has been checked with PEMS for gaseous pollutants since 2014. To strengthen emissions regulations with a view to minimise the differences between on-road and laboratory emission levels in some cases, PEMS testing, including solid particle number (SPN), was introduced for the type-approval of light-duty vehicles in Europe in 2017 and for in-service conformity in 2019. SPN-PEMS for heavy-duty engines will be introduced in 2021. This paper gives an overview of the studies for SPN-PEMS from early 2013 with the first prototypes until the latest testing and improvements in 2019. The first prototype diffusion charger (DC) based systems had high differences from the reference laboratory systems at the first light-duty vehicles campaign. Tightening of the technical requirements and improvements from the instrument manufacturers resulted in differences of around 50%. Similar differences were found in an inter-laboratory comparison exercise with the best performing DC- and CPC- (condensation particle counter) based system. The heavy-duty evaluation phase at a single lab and later at various European laboratories revealed higher differences due to the small size of the urea generated particles and their high charge at elevated temperatures. This issue, along with robustness at low ambient temperatures, was addressed by the instrument manufacturers bringing the measurement uncertainty to the 50% levels. This measurement uncertainty needs to be considered at the on-road emission results measured with PEMS.

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Abstract: This study assessed the on-road gaseous and particulate emissions from three current technology gasoline direct injection (GDI) vehicles using portable emissions measurement systems (PEMS). Two vehicles were also retrofitted with catalyzed gasoline particulate filters (GPFs). All vehicles were exercised over four routes with different topological and environmental characteristics, representing urban, rural, highway, and high-altitude driving conditions. The results showed strong reductions in particulate mass (PM), soot mass, and particle number emissions with the use of GPFs. Particle emissions were found to be highest during urban and high-altitude driving compared to highway driving. The reduction efficiency of the GPFs ranged from 44% to 99% for overall soot mass emissions. Similar efficiencies were found for particle number and PM mass emissions. In most cases, nitrogen oxide (NOx) emissions showed improvements with the catalyzed GPFs in the underfloor position with the additional catalytic volume. No significant differences were seen in carbon dioxide (CO2) and carbon monoxide (CO) emissions with the vehicles retrofitted with GPFs.

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15 Oct 2020-Fuel
TL;DR: An advanced calibration methodology is proposed for flex-fuel engines in this study based on the knowledge gained through the preparation of this article and complex optimizers like neural networks can be used in the proposed methodology to initiate real-time calibration for ideal flex- fuel engine output responses.
Abstract: As the vehicle technology evolves and becomes more complex, the ability to monitor certain uncontrollable factors is possible through various engine management system calibration methods. Additionally, different optimization approaches assist in improving engine output characteristics. Advances in fuel production from unique feedstocks have paved a way for the introduction of innovative flex-fuel engines. These engines are made multi-fuel adaptive by utilizing appropriate calibration and optimization approaches. Since numerous researches have been carried out in internal combustion engine calibration, operating on alternative fuels, it is quite hard to maintain a record for this wealth of information. Therefore to bridge this issue, this study intends to organize and provide the reader with a retrospective view of selective studies undergone in the field of engine calibration using different tuning techniques. The objective of this study is to assist engine calibration enthusiasts on selecting an apt engine calibration technique for their application which can be flexible for multiple fuel types. Studies revealed that model-based calibration assisted by Gaussian process modelling and Design of Experiment application is adequate for calibrating an engine operating on alternative fuels. Additionally, calibration methodologies followed for certain fuel types and compositions are highlighted in detail. Furthermore, an advanced calibration methodology is proposed for flex-fuel engines in this study based on the knowledge gained through the preparation of this article. To further enhance accuracy, complex optimizers like neural networks can be used in the proposed methodology to initiate real-time calibration for ideal flex-fuel engine output responses.

11 citations


Journal ArticleDOI
Abstract: The effects of different olefin contents in fuel (nominally 8.2 and 17.2% in volume) on the performance and exhaust emissions of a modern gasoline direct injection engine at speeds of 1500, 3500, a...

7 citations



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Journal ArticleDOI
Abstract: Limited field data are available for analyses of fuel use and emissions of nonroad diesel construction equipment. This paper summarizes the results of field research that used a portable emissions monitoring system to collect fuel use and emissions data from eight backhoes, six bulldozers, three excavators, four generators, six motor graders, three off-road trucks, one skid-steer loader, three track loaders, and five wheel loaders while they performed various duty cycles. These tests produced approximately 119 h of field data for petroleum diesel and approximately 48 h for B20 biodiesel. Engine attribute data including horsepower, displacement, model year, engine tier, and engine load were collected to determine these factors' influence on fuel use rates and emission rates of nitrogen oxides, hydrocarbons, carbon monoxide, carbon dioxide, and opacity. Mass per time fuel use rates were developed for each item of equipment, as were mass per time and mass per fuel used emission rates for each pollutant. For ...

87 citations


Journal ArticleDOI
TL;DR: In this study, four commercial PEMS were compared with a Federal Reference Method for measuring emissions from a back-up generator over steady-state loads and a diesel truck on transient and steady- state chassis dynamometer tests.
Abstract: There is considerable interest in portable emissions measurement systems (PEMS) for emission inventory and regulatory applications. For this study, four commercial PEMS were compared with a Federal Reference Method (FRM) for measuring emissions from a back-up generator (BUG) over steady-state loads and a diesel truck on transient and steady-state chassis dynamometer tests. The agreement between the PEMS and the FRM varied depending on the pollutant and the particular PEMS tested for both the BUG and chassis dynamometer testing. The best performing PEMS for both the BUG and chassis testing was within ∼12% for NOx of the FRM. For the BUG testing, several PEMS showed agreement with the FRM within ∼5% for CO2. For the chassis dynamometer testing, the best PEMS showed agreement typically within ∼5% for CO2. PM measurements for the BUG testing were low compared to the FRM, with the best measurements ∼20% lower. For the chassis testing, two PM PEMS showed a good correlation but a high bias, while the correlation...

72 citations


Journal ArticleDOI
Abstract: On-road comparisons were made between a mobile emissions laboratory (MEL) meeting federal standards and a portable emissions measurement system (PEMS). These comparisons were made over different conditions; including road grade, vibration, altitude, electric fields, and humidity with the PEMS mounted inside and outside of the tractor's cab. Brake-specific emissions were calculated to explore error differences between the MEL and PEMS during the Not-To-Exceed (NTE) engine operating zone. The PEMS brake-specific NOx (bsNOx) NTE emissions were biased high relative to the MEL and, in general, were about 8% of the 2007 in-use NTE NO x standard of 2.68 g kW −1 h −1 (2.0 g hp −1 h −1 ). The bsCO 2 emissions for the PEMS were also consistently biased high relative to the MEL, with an average deviation of +4% ± 2%. NMHC and CO emissions were very low and typically less than 1% of the NTE threshold. This research was part of a comprehensive program to determine the “allowance” when PEMS are used for in-use compliance testing of heavy-duty diesel vehicles (HDDVs).

57 citations