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Atmosphere
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Traffic-Related Emissions
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Traffic-Related Emissions

A special issue of Atmosphere (ISSN 2073-4433). This special issue belongs to the section "Air Quality".

Deadline for manuscript submissions: closed (15 July 2019) | Viewed by 43855

Special Issue Editor

Dr. Leonidas Ntziachristos

E-Mail Website
Guest Editor
Mechanical Engineering Department, Aristotle University of Thessaloniki, P.O. Box 458, GR 54124 Thessaloniki, Greece
Interests: vehicle emissions; ship emissions; exhaust particles; emission inventorying; emission models

Special Issue Information

Dear Colleagues,

Road transport emissions in the urban environment have recently received increased scholarly attention for a number of reasons. Firstly due to failures to reach environmental targets, especially for NOx, and secondly, because new emission standards are scheduled for introduction around the world that will potentially create conflicts with greenhouse gas targets. Scholarly attention is also being given to new testing techniques and measurement methods for a wider range of pollutants. There is a need to characterize the number of particles and the ammonia and nitrous oxide emissions produced by vehicles with advanced emission control systems under real driving emission conditions, in addition to long-regulated air pollutants. The characterization of the potential to form secondary aerosols is also appearing as a necessary emerging area of study. Finally, the mix of vehicles is changing with the inclusion of alternative and improved fuels, new combustion and emission control methods and the introduction of electrified vehicles. All these changes are creating a dynamic new environment with complex interactions.

This Special Issue aims to collect contributions in any of these areas, involving measurement or simulation techniques, with the aim of providing new insights into the future challenges of traffic-related emissions.

Dr. Leonidas Ntziachristos
Guest Editor

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Keywords

  • vehicle emissions
  • exhaust measurements
  • PEMS
  • air pollutants
  • greenhouse gases
  • secondary organic aerosols
  • exhaust emission control

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Published Papers (9 papers)

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Research

11 pages, 2332 KiB  
Article
Tailpipe VOC Emissions from Late Model Gasoline Passenger Vehicles in the Japanese Market
by Hiroo Hata, Megumi Okada, Chikage Funakubo and Junya Hoshi
Atmosphere 2019, 10(10), 621; https://doi.org/10.3390/atmos10100621 - 15 Oct 2019
Cited by 11 | Viewed by 4092
Abstract
High concentrations of tropospheric ozone remain a concern, and strategies to reduce the precursors of ozone, volatile organic compounds (VOCs) and nitrogen oxides, have been established in many countries. In this study, chassis dynamometer experiments were conducted for 25 late model gasoline passenger [...] Read more.
High concentrations of tropospheric ozone remain a concern, and strategies to reduce the precursors of ozone, volatile organic compounds (VOCs) and nitrogen oxides, have been established in many countries. In this study, chassis dynamometer experiments were conducted for 25 late model gasoline passenger vehicles in the Japanese market to evaluate VOC emission trends. Tailpipe emissions were collected and analyzed using gas chromatography mass spectrometer and flame ionization detector, and liquid chromatography–mass spectrometry (LC-MS). Results showed that tailpipe VOC emissions increased linearly with vehicle mileage due to deterioration of the three-way catalysis converter used to purify the toxic components in vehicle emissions. Distance normalized total VOC emissions showed that port injection mini-sized vehicles were effective in decreasing tailpipe VOC emissions because of their low vehicle weight. The VOC composition of tailpipe emissions was dependent on the fuel type (regular or premium gasoline). VOC emissions from hybrid vehicles were similar to those of other vehicles because cooling of the three-way catalysis converter during battery operations sometimes tended to reduce catalyst effectiveness during engine operations. However, it can also be assumed that each manufacturer is aware of this phenomenon and is taking action. Further monitoring of hybrid vehicles is warranted to ensure that these vehicles remain an effective means of mitigating air pollution. Full article
(This article belongs to the Special Issue Traffic-Related Emissions)
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17 pages, 1799 KiB  
Article
Measuring On-Road Vehicle Emissions with Multiple Instruments Including Remote Sensing
by Robin Smit and Phil Kingston
Atmosphere 2019, 10(9), 516; https://doi.org/10.3390/atmos10090516 - 3 Sep 2019
Cited by 25 | Viewed by 5326
Abstract
The objective of this paper is to use remote sensing to measure on-road emissions and to examine the impact and usefulness of additional measurement devices at three sites. Supplementing remote sensing device (RSD) equipment with additional equipment increased the capture rate by almost [...] Read more.
The objective of this paper is to use remote sensing to measure on-road emissions and to examine the impact and usefulness of additional measurement devices at three sites. Supplementing remote sensing device (RSD) equipment with additional equipment increased the capture rate by almost 10%. Post-processing of raw data is essential to obtain useful and accurate information. A method is presented to identify vehicles with excessive emission levels (high emitters). First, an anomaly detection method is applied, followed by identification of cold start operating conditions using infrared vehicle profiles. Using this method, 0.6% of the vehicles in the full (enhanced) RSD data were identified as high emitters, of which 35% are likely in cold start mode where emissions typically stabilize to low hot running emission levels within a few minutes. Analysis of NOx RSD data confirms that poor real-world NOx performance of Euro 4/5 light-duty diesel vehicles observed around the world is also evident in Australian measurements. This research suggests that the continued dieselisation in Australia, in particular under the current Euro 5 emission standards and the more stringent NO2 air quality criteria expected in 2020 and 2025, could potentially result in local air quality issues near busy roads. Full article
(This article belongs to the Special Issue Traffic-Related Emissions)
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17 pages, 7828 KiB  
Article
A NOx Emission Model Incorporating Temperature for Heavy-Duty Diesel Vehicles with Urea-SCR Systems Based on Field Operating Modes
by Xin Wang, Guohua Song, Yizheng Wu, Lei Yu and Zhiqiang Zhai
Atmosphere 2019, 10(6), 337; https://doi.org/10.3390/atmos10060337 - 20 Jun 2019
Cited by 22 | Viewed by 5459
Abstract
The selective catalytic reduction (SCR) is the most commonly used technique for decreasing the emissions of nitrogen oxides (NOx) from heavy-duty diesel vehicles (HDDVs). However, the same injection strategy in the SCR system shows significant variations in NOx emissions even at the same [...] Read more.
The selective catalytic reduction (SCR) is the most commonly used technique for decreasing the emissions of nitrogen oxides (NOx) from heavy-duty diesel vehicles (HDDVs). However, the same injection strategy in the SCR system shows significant variations in NOx emissions even at the same operating mode. This kind of heterogeneity poses challenges to the development of emission inventories and to the assessment of emission reductions. Existing studies indicate that these differences are related to the exhaust temperature. In this study, an emission model is established for different source types of HDDVs based on the real-time data of operating modes. Firstly, the initial NOx emission rates (ERs) model is established using the field vehicle emission data. Secondly, a temperature model of the vehicle exhaust based on the vehicle specific power (VSP) and the heat loss coefficient is established by analyzing the influencing factors of the NOx conversion efficiency. Thirdly, the models of NOx emissions and the urea consumption are developed based on the chemical reaction in the SCR system. Finally, the NOx emissions are compared with the real-world emissions and the estimations by the proposed model and the Motor Vehicle Emission Simulator (MOVES). This indicates that the relative error by the proposed method is 12.5% lower than those calculated by MOVES. The characteristics of NOx emissions under different operating modes are analyzed through the proposed model. The results indicate that the NOx conversion rate of heavy-duty diesel trucks (HDDTs) is 39.2% higher than that of urban diesel transit buses (UDTBs). Full article
(This article belongs to the Special Issue Traffic-Related Emissions)
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14 pages, 6780 KiB  
Article
Mesoscopic Urban-Traffic Simulation Based on Mobility Behavior to Calculate NOx Emissions Caused by Private Motorized Transport
by Simon Plakolb, Georg Jäger, Christian Hofer and Manfred Füllsack
Atmosphere 2019, 10(6), 293; https://doi.org/10.3390/atmos10060293 - 28 May 2019
Cited by 11 | Viewed by 3702
Abstract
Motorized transport is one of the main contributors to anthropogenic CO 2 emissions, which cause global warming. Other emissions, like nitrogen oxides or carbon monoxide, are detrimental to human health. A prominent way to understand and thus be able to minimize emissions is [...] Read more.
Motorized transport is one of the main contributors to anthropogenic CO 2 emissions, which cause global warming. Other emissions, like nitrogen oxides or carbon monoxide, are detrimental to human health. A prominent way to understand and thus be able to minimize emissions is by using traffic simulations to evaluate different scenarios. In that way, one can find out which policies, technical innovations, or behavioral changes can lead to a decrease in emissions. Since the effect of CO 2 is on a global scale, a macroscopic model is often enough to find reasonable results. However, NO x emissions can also have a direct, local effect. Therefore, it is interesting to investigate these emissions on a mesoscopic scale, to gain insight into the local distribution of this pollutant. In this study, we used a traffic model that, contrary to most other state-of-the-art traffic simulations, does not require an origin–destination matrix as an input, but calculates it from mobility behavior extracted from a survey. We then generated agents with realistic mobility behavior that perform their daily trips and calculate key features like congestion and emissions for every edge of the road network. Our approach has the additional advantage of allowing to investigate technical, juridical, as well as behavioral changes, all within the same framework. It is then possible to identify strategies that minimize NO x emissions caused by private motorized transport. Evaluation showed good agreement with reality in terms of local and temporal resolution. Especially when looking at the sum of emissions, the main feature for evaluating policies, and deviations between our simulation and available statistics were negligible. We found that, from all scenarios we investigated, the ban of old diesel cars is the most promising policy: By replacing all diesel cars built in 2005 or earlier with petrol cars of the same age, NO x emissions could drop by roughly a third. Full article
(This article belongs to the Special Issue Traffic-Related Emissions)
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14 pages, 2147 KiB  
Article
A Test Stand Study on the Volatile Emissions of a Passenger Car Brake Assembly
by Guido Perricone, Vlastimil Matĕjka, Mattia Alemani, Jens Wahlström and Ulf Olofsson
Atmosphere 2019, 10(5), 263; https://doi.org/10.3390/atmos10050263 - 10 May 2019
Cited by 35 | Viewed by 4927
Abstract
Brake-related airborne particulate matter contributes to urban emissions in the transport sector. Recent research demonstrated a clear dependence of the number of ultra-fine particles on the disc brake temperature. Above the so-called transition temperature, the number of ultra-fine particles increases dramatically (several magnitudes). [...] Read more.
Brake-related airborne particulate matter contributes to urban emissions in the transport sector. Recent research demonstrated a clear dependence of the number of ultra-fine particles on the disc brake temperature. Above the so-called transition temperature, the number of ultra-fine particles increases dramatically (several magnitudes). As for exhaust emissions, part of the emissions released during braking can be in the volatile fraction. For this reason, a disc brake test stand specifically designed for aerosol research was equipped with three different aerosol sampling instruments: (i) a standard cascade impactor, (ii) a cascade impactor operating at high temperature with a heated sampling line, and (iii) a standard cascade impactor with a thermodenuder. Tests with a brake assembly representative of European passenger vehicles were executed, and the concentration of released airborne particles was determined. The results showed a decrease by several magnitudes in the concentration (in the size range of below 200 nm) using the cascade impactor operating at 180 °C with the sampling line heated to 200 °C. A further decrease in the concentration of airborne particles with size fractions below 200 nm was measured using a standard cascade impactor with a thermodenuder heated to 300 °C. Full article
(This article belongs to the Special Issue Traffic-Related Emissions)
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29 pages, 3868 KiB  
Article
Emission Factors Derived from 13 Euro 6b Light-Duty Vehicles Based on Laboratory and On-Road Measurements
by Victor Valverde, Bernat Adrià Mora, Michaël Clairotte, Jelica Pavlovic, Ricardo Suarez-Bertoa, Barouch Giechaskiel, Covadonga Astorga-LLorens and Georgios Fontaras
Atmosphere 2019, 10(5), 243; https://doi.org/10.3390/atmos10050243 - 2 May 2019
Cited by 63 | Viewed by 7202
Abstract
Tailpipe emissions of a pool of 13 Euro 6b light-duty vehicles (eight diesel and five gasoline-powered) were measured over an extensive experimental campaign that included laboratory (chassis dynamometer), and on-road tests (using a portable emissions measurement system). The New European Driving Cycle (NEDC) [...] Read more.
Tailpipe emissions of a pool of 13 Euro 6b light-duty vehicles (eight diesel and five gasoline-powered) were measured over an extensive experimental campaign that included laboratory (chassis dynamometer), and on-road tests (using a portable emissions measurement system). The New European Driving Cycle (NEDC) and the Worldwide harmonised Light-duty vehicles Test Cycle (WLTC) were driven in the laboratory following standard and extended testing procedures (such as low temperatures, use of auxiliaries, modified speed trace). On-road tests were conducted in real traffic conditions, within and outside the boundary conditions of the regulated European Real-Driving Emissions (RDE) test. Nitrogen oxides (NOX), particle number (PN), carbon monoxide (CO), total hydrocarbons (HC), and carbon dioxide (CO2) emission factors were developed considering the whole cycles, their sub-cycles, and the first 300 s of each test to assess the cold start effect. Despite complying with the NEDC type approval NOX limit, diesel vehicles emitted, on average, over the WLTC and the RDE 2.1 and 6.7 times more than the standard limit, respectively. Diesel vehicles equipped with only a Lean NOX trap (LNT) averaged six and two times more emissions over the WLTC and the RDE, respectively, than diesel vehicles equipped with a selective catalytic reduction (SCR) catalyst. Gasoline vehicles with direct injection (GDI) emitted eight times more NOX than those with port fuel injection (PFI) on RDE tests. Large NOX emissions on the urban section were also recorded for GDIs (122 mg/km). Diesel particle filters were mounted on all diesel vehicles, resulting in low particle number emission (~1010 #/km) over all testing conditions including low temperature and high dynamicity. GDIs (~1012 #/km) and PFIs (~1011 #/km) had PN emissions that were, on average, two and one order of magnitude higher than for diesel vehicles, respectively, with significant contribution from the cold start. PFIs yielded high CO emission factors under high load operation reaching on average 2.2 g/km and 3.8 g/km on WLTC extra-high and RDE motorway, respectively. The average on-road CO2 emissions were ~33% and 41% higher than the declared CO2 emissions at type-approval for diesel and gasoline vehicles, respectively. The use of auxiliaries (AC and lights on) over the NEDC led to an increase of ~20% of CO2 emissions for both diesel and gasoline vehicles. Results for NOX, CO and CO2 were used to derive average on-road emission factors that are in good agreement with the emission factors proposed by the EMEP/EEA guidebook. Full article
(This article belongs to the Special Issue Traffic-Related Emissions)
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17 pages, 3848 KiB  
Article
Emissions of a Euro 6b Diesel Passenger Car Retrofitted with a Solid Ammonia Reduction System
by Barouch Giechaskiel, Ricardo Suarez-Bertoa, Tero Lahde, Michael Clairotte, Massimo Carriero, Pierre Bonnel and Maurizio Maggiore
Atmosphere 2019, 10(4), 180; https://doi.org/10.3390/atmos10040180 - 3 Apr 2019
Cited by 17 | Viewed by 4101
Abstract
Nitrogen oxides (NOx) emissions from diesel vehicles are a serious environmental concern. Prior to the introduction of on-road tests at type approval, vehicle on-road NOx emissions were found many times higher than the applicable limits. Retrofitting an existing vehicle is [...] Read more.
Nitrogen oxides (NOx) emissions from diesel vehicles are a serious environmental concern. Prior to the introduction of on-road tests at type approval, vehicle on-road NOx emissions were found many times higher than the applicable limits. Retrofitting an existing vehicle is a short/mid-term solution. We evaluated a NOx reduction retrofit system installed on a Euro 6b diesel passenger car both in the laboratory and on the road. The retrofit consisted of an under-floor SCR (selective catalytic reduction) for NOx catalyst in combination with a solid ammonia-based dosing system as the NOx reductant. The retrofit reduced NOx emissions from 25% (50 mg/km) to 82% (725 mg/km) both in the laboratory and on the road. The minimum reduction was achieved at cold start cycles and the maximum at hot start cycles. The retrofit had small effect on CO2 (fuel consumption). No ammonia emissions were detected and the N2O increase was negligible at cold start cycles, but up to 18 mg/km at hot start cycles. The results showed that the retrofit technology could be beneficial even for high emitting Euro 6b diesel vehicles. Full article
(This article belongs to the Special Issue Traffic-Related Emissions)
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12 pages, 3393 KiB  
Article
Effects of the Particulate Matter Index and Particulate Evaluation Index of the Primary Reference Fuel on Particulate Emissions from Gasoline Direct Injection Vehicles
by Yaowei Zhao, Xinghu Li, Shouxin Hu and Chenfei Ma
Atmosphere 2019, 10(3), 111; https://doi.org/10.3390/atmos10030111 - 1 Mar 2019
Cited by 10 | Viewed by 3753
Abstract
The purpose of this experimental study was to evaluate the range of particulate mass (PM) and particulate number (PN) results from gasoline direct injection (GDI) vehicles by using four test fuels with a range of particulate matter index (PMI) from 1.38 to 2.39 [...] Read more.
The purpose of this experimental study was to evaluate the range of particulate mass (PM) and particulate number (PN) results from gasoline direct injection (GDI) vehicles by using four test fuels with a range of particulate matter index (PMI) from 1.38 to 2.39 and particulate evaluation index (PEI) from 0.89 to 1.92. The properties of four test fuels were analyzed with detailed hydrocarbon analysis (DHA). Two passenger cars with a GDI engine were tested with four test fuels by conducting the China 6 test procedure, which is equivalent to the worldwide harmonized light-duty vehicle test procedure (WLTP). When the fuels could meet the China 6 primary reference fuel standard with PMI from 1.38 to 2.04 and PEI from 0.89 to 1.59, the PM variation of Vehicle B was from 1.94 mg/km to 3.32 mg/km and of Vehicle A was from 2.55 mg/km to 4.15 mg/km, respectively. In addition, the PN variation of Vehicle B was from 1.57 × 1012 #/km to 3.38 × 1012 #/km and of Vehicle A was from 3.02 × 1012 #/km to 4.80 × 1012 #/km. It was noted that the two different cars had a unique response and sensitivity by using the different fuels, but PMI and PEI did trend with both the PM and the PN response. All PM and PN results from the two cars had an excellent correlation R2 > 0.94 with PMI and R2 > 0.90 with PEI. Therefore, PMI/PEI would be the appropriate specification for sooting tendency in reference fuel standards of emission regulations. Full article
(This article belongs to the Special Issue Traffic-Related Emissions)
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14 pages, 1922 KiB  
Article
Investigation and Prediction of Heavy-Duty Diesel Passenger Bus Emissions in Hainan Using a COPERT Model
by Feng Li, Jihui Zhuang, Xiaoming Cheng, Mengliang Li, Jiaxing Wang and Zhenzheng Yan
Atmosphere 2019, 10(3), 106; https://doi.org/10.3390/atmos10030106 - 27 Feb 2019
Cited by 30 | Viewed by 4390
Abstract
To investigate the emission status and predict the future trends of heavy-duty diesel passenger buses in Hainan Province, the technical level distribution, activity characteristics, and operating conditions of heavy-duty diesel passenger buses were statistically analyzed. The emissions of CO, CO2, NO [...] Read more.
To investigate the emission status and predict the future trends of heavy-duty diesel passenger buses in Hainan Province, the technical level distribution, activity characteristics, and operating conditions of heavy-duty diesel passenger buses were statistically analyzed. The emissions of CO, CO2, NOX, and PM of the province’s heavy-duty diesel passenger buses in 2017 were calculated by the COPERT model. The Portable Emission Measurement System was applied to the calibration of emission factors calculated by the model to improve the accuracy of emission predictions. The prediction of emission trends sets three different scenarios: baseline scenarios (BAS), emission reduction standard scenario (ERS), and emission reduction standard and replacement by electric vehicle scenario (ERS and REV). The gray model was used to predict the number of heavy-duty diesel passenger buses in the three scenarios and combined with the calibrated emission factors to predict the emission trends under different scenarios. Results show that the ERS will reduce CO, CO2, NOX, and PM emissions by approximately 23%, 12%, 23%, and 46% respectively, in 2025 compared with BAS. ERS and REV will reduce CO, CO2, NOX, and PM emissions by approximately 38%, 33%, 38%, and 50% for the three emissions, compared with the BAS. Full article
(This article belongs to the Special Issue Traffic-Related Emissions)
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