Vehicle Emissions: New Challenges and Potential Solutions

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

Deadline for manuscript submissions: closed (31 January 2023) | Viewed by 25540

Special Issue Editor


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Guest Editor
Joint Research Centre (JRC), European Commission, 21027 Ispra, Italy
Interests: vehicle emissions; particle number emissions; on-board monitoring

Special Issue Information

Dear Colleagues,

Although mobility brings many benefits for its users, it does not come without costs for society. These include greenhouse gas emissions, air, noise and water pollution. By far the most serious challenge facing the transport sector is to significantly reduce its emissions and become more sustainable. Greener low-emission vehicles are key for reducing the impact of transport on human health and the environment, particularly in cities.

Increasingly stringent emission standards have been introduced or are planned in several countries to reduce greenhouse gas (GHG) and pollutant emissions from vehicles, expected to be monitored and controlled under wider operating/driving conditions as well. The range of regulated pollutants is becoming wider, with non-exhaust emissions such as brake and tyre wear particles drawing more and more attention from regulatory bodies. New emission control concepts such as on-board monitoring and remote sensing are being explored to identify malfunctioning or tampered vehicles. Periodic technical inspection (PTI) in some countries have added the particle number to detect malfunctioning particulate filters, whereas methods for detecting malfunctioning NOx abatement systems are under investigation. On the vehicle side, the increasing complexity of the technology used to comply with the standards (hybridization, new emission control devices, new operating strategies, etc.), as well as the use of alternative fuels, pose new challenges to properly control the environmental performance of modern vehicles.

This still requires a significant research effort, both for vehicle technology and measurement instruments/techniques. Upcoming regulations will need new instruments with new principles of measurements, sensitive enough for low emission levels, particularly for on-board systems. Measuring increasingly low emission levels in extreme conditions is a challenge and calibration procedures are important. Advanced modeling and simulation tools are essential, not only for research and development (R&D), but also for regulatory purposes. This Special Issue collects the latest results of the most advanced research in the field of vehicle emissions.

Giorgio Martini
Guest Editor

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Keywords

  • vehicle emissions
  • non-exhaust emissions
  • real driving emissions
  • on-board monitoring
  • remote sensing
  • periodic technical inspection (PTI)
  • after-treatment technologies
  • unregulated pollutants
  • measuring equipment and calibration
  • testing methodologies
  • alternative fuels
  • hybrid vehicles
  • PEMS

Published Papers (13 papers)

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Research

13 pages, 3825 KiB  
Article
Off-Cycle Emissions of Particle Number from Gasoline and DPF Diesel Passenger Cars in High-Load Conditions
by Hiroyuki Yamada, Taichi Kimura, Hidenori Konno and Yoshinori Kondo
Atmosphere 2023, 14(4), 732; https://doi.org/10.3390/atmos14040732 - 18 Apr 2023
Viewed by 1192
Abstract
To evaluate regulated gases and solid particle number (SPN) emissions in high-load off-cycle conditions, two diesel vehicles with a diesel particulate filter (DPF) and a urea selective catalytic reduction (SCR) system, respectively, and four gasoline port fuel injection (PFI) vehicles were tested with [...] Read more.
To evaluate regulated gases and solid particle number (SPN) emissions in high-load off-cycle conditions, two diesel vehicles with a diesel particulate filter (DPF) and a urea selective catalytic reduction (SCR) system, respectively, and four gasoline port fuel injection (PFI) vehicles were tested with the worldwide light-duty test cycle, including an extra-high (Ex-hi) phase. All the tested vehicles were developed for the Japanese market and did not comply with the Ex-hi phase. All vehicles exhibited higher CO2 emissions in the Ex-hi phase than in low, the mid and high phases. Increased NOx and SPN10-23 emissions were observed with the DPF vehicle. These increased emissions were due to the occurrence of passive regeneration of the DPF, and the urea SCR system was stopped as a result. The small gasoline PFI cars showed increased CO and SPN emissions in the Ex-hi phase. These emissions were due to enrichment control, which occurred in a quite high load operation condition. The feature of higher emissions with enrichment control differed from that observed in a warming-up process in the cold-start mode. SPN23 increased mainly in the warming-up process, whereas SPN10-23 increased in the Ex-hi phase with enrichment control. Hybrid vehicles seem to have fewer opportunities to show the enrichment control due to motor assist. Full article
(This article belongs to the Special Issue Vehicle Emissions: New Challenges and Potential Solutions)
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24 pages, 3526 KiB  
Article
A Multipurpose Simulation Approach for Hybrid Electric Vehicles to Support the European CO2 Emissions Framework
by Alessandro Tansini, Georgios Fontaras and Federico Millo
Atmosphere 2023, 14(3), 587; https://doi.org/10.3390/atmos14030587 - 18 Mar 2023
Cited by 3 | Viewed by 2447
Abstract
Hybrid Electric Vehicles (HEVs) are a prominent solution for reducing CO2 emissions from transport in Europe. They are equipped with at least two propulsion energy converters, an Internal Combustion Engine (ICE) and one or more Electric Machines (EMs), operated in a way [...] Read more.
Hybrid Electric Vehicles (HEVs) are a prominent solution for reducing CO2 emissions from transport in Europe. They are equipped with at least two propulsion energy converters, an Internal Combustion Engine (ICE) and one or more Electric Machines (EMs), operated in a way to exploit synergies and achieve fuel efficiency. Because of the variety in configurations and strategies, the use of simulation is essential for vehicle development and characterisation of energy consumption. This paper introduces a novel simulation approach to estimate the CO2 emissions from different hybrid architectures (series, parallel, power-split) and electrification degrees (mild, full, plug-in and range extender) that is relatively simple, flexible and accurate. The approach identifies the optimal power split between the energy converters for any given time in a driving cycle according to three evaluation levels: supervisor, ICE manager and optimiser. The latter relies on the Equivalent Consumption Minimisation Strategy (ECMS) and the limitations imposed by the other two layers. Six light-duty HEVs with different hybrid architectures were tested to support the development of the approach. The results show an indicative accuracy of ±5%, enabling to run assessments of hybrid powertrain solutions and supporting regulatory and consumer information initiatives. Full article
(This article belongs to the Special Issue Vehicle Emissions: New Challenges and Potential Solutions)
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23 pages, 3596 KiB  
Article
Investigating the Incorporation of Idle, High Idle, and Driving Acceleration NOx Emissions Tests into the Periodic Technical Inspection Procedures
by Daisy Thomas, Gurdas S. Sandhu, Thomas Nilsson and Stefan Bjurkvist
Atmosphere 2023, 14(3), 536; https://doi.org/10.3390/atmos14030536 - 10 Mar 2023
Viewed by 1741
Abstract
NOx pollution is one of the greatest air quality issues that urban areas face today, particularly within the European Union (EU), yet currently this pollutant is only controlled through the homologation process. There is currently no periodic technical inspection (PTI) process for NOx [...] Read more.
NOx pollution is one of the greatest air quality issues that urban areas face today, particularly within the European Union (EU), yet currently this pollutant is only controlled through the homologation process. There is currently no periodic technical inspection (PTI) process for NOx emissions within the EU, leaving a weakness in the legislation that is currently allowing high polluters to negatively impact air quality. Work needs to be performed to incorporate a simple, quick, inexpensive, and representative test to accurately identify these high emitters within the on-road vehicle fleet. This paper investigates options for the incorporation of a NOx test into the EU PTI test procedures. In a trial constituting over 600 vehicles, a 3DATX parSYNC was used to measure the NOx emissions over a series of short test types. These are an idle test, two types of high idle test (a constant high idle and a rapid high idle), and an on-road driving dynamic acceleration test. The repeatability of all three test types was good. The NOx concentrations have strong correlations to the mass emissions for each test type, with the use of mean concentrations being deemed more representative than the use of maximum concentrations. The mean results across the tested fleet are calculated and used to define pass/fail thresholds for different vehicle types. The findings of this work show that multiple test methods have the potential to characterize NOx emissions from a vehicle, but in order to catch high emitters on a PTI test, the unloaded idle and high idle test types are not suitable substitutes for a dynamic acceleration test, particularly for petrol vehicles. Full article
(This article belongs to the Special Issue Vehicle Emissions: New Challenges and Potential Solutions)
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17 pages, 2607 KiB  
Article
Characterization of Soot Loading and Filtration Efficiency of a Gasoline Particulate Filter with Photoacoustic Sensor and Particle Number Counting Systems
by Kazuki Nakamura, Yuta Sugaya, Kyohei Yamaguchi, Jin Kusaka, Michael Arndt and Christos Dardiotis
Atmosphere 2023, 14(3), 476; https://doi.org/10.3390/atmos14030476 - 28 Feb 2023
Cited by 1 | Viewed by 1353
Abstract
An optimum operation of a gasoline particulate filter (GPF) for a gasoline direct injection vehicle in terms of its performance of pressure drop, soot loading, and filtration efficiency becomes inevitable to fulfill upcoming emission regulations. This paper proposes a methodology to characterize the [...] Read more.
An optimum operation of a gasoline particulate filter (GPF) for a gasoline direct injection vehicle in terms of its performance of pressure drop, soot loading, and filtration efficiency becomes inevitable to fulfill upcoming emission regulations. This paper proposes a methodology to characterize the GPF performance for validation of simulation models for more precise operation strategies along with future legislative requirements. The feasibility was examined through experiments of miniature GPF samples using a synthetic particle generator. Firstly, permeability of the GPF walls was estimated to be 6.9 ± 1.5 × 10−13 m2 by a flow resistance descriptor model, which was in good agreement with its pore structure. Secondly, photoacoustic sensor systems indicated soot accumulation inside the GPFs in real time thanks to linear correlations between sensor signals and soot mass concentrations in exhaust. Thirdly, particle number counting systems compliant with respective regulatory technical requirements exhibited time-resolved filtration efficiencies of the GPFs in conjunction with solid particle number emissions whose diameter was larger than 10 nm and 23 nm. The filtration efficiencies at a clean state of the GPF were 0.78 and 0.77, respectively. The slight difference could be explained by Brownian diffusion and interception for particle filtration. Full article
(This article belongs to the Special Issue Vehicle Emissions: New Challenges and Potential Solutions)
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23 pages, 8143 KiB  
Article
Achieving Zero-Impact Emissions with a Gasoline Passenger Car
by Robert Maurer, Theodoros Kossioris, Stefan Sterlepper, Marco Günther and Stefan Pischinger
Atmosphere 2023, 14(2), 313; https://doi.org/10.3390/atmos14020313 - 4 Feb 2023
Cited by 5 | Viewed by 2591
Abstract
The Euro 7 legislation and the Zero-Impact Emissions concept aim at significantly improving air quality. Technologies that reduce pollutant emissions beyond current gasoline passenger cars have already been intensively investigated, but a holistic system layout considering extended boundary conditions is missing so far. [...] Read more.
The Euro 7 legislation and the Zero-Impact Emissions concept aim at significantly improving air quality. Technologies that reduce pollutant emissions beyond current gasoline passenger cars have already been intensively investigated, but a holistic system layout considering extended boundary conditions is missing so far. This paper therefore develops technical solutions to achieve a Euro 7 scenario and Zero-Impact Emissions for a 2030+ vehicle. First, challenging test scenarios are identified to develop compliant vehicles. The scenarios cover extreme conditions in real-world driving, such as hot and cold ambient conditions, stop-and-go in rural areas or high speed and steep gradients on highways. Different technology options are discussed and selected for the investigations. An empirical–physical simulation model for the exhaust gas aftertreatment system is extended with new technologies, such as an electrical heater disc in front of the catalyst or a burner in the exhaust system. In addition to stoichiometric engine operation and increased catalyst volume, the results show that the expected Euro 7 regulations can be achieved in all extreme scenarios by combining additional exhaust gas heating with engine power limitation or pre-heating. Moreover, even Zero-Impact Emissions are achieved in most cases with the same technology options. Full article
(This article belongs to the Special Issue Vehicle Emissions: New Challenges and Potential Solutions)
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11 pages, 1952 KiB  
Article
Comparative Analysis of Emission Characteristics of In-Use China II–V Gasoline, Hybrid, Diesel-Fueled Vehicles
by Ye Zhang, Yating Song, Tianshi Feng and Yanyan Chen
Atmosphere 2023, 14(2), 272; https://doi.org/10.3390/atmos14020272 - 29 Jan 2023
Cited by 3 | Viewed by 1624
Abstract
Increasingly stringent regulations regarding vehicle emissions have contributed to the diversification of vehicle technologies, resulting in the increasing complexity of typical vehicles that make up a fleet. In order to investigate the real gas emissions of different typical vehicles, tests were conducted using [...] Read more.
Increasingly stringent regulations regarding vehicle emissions have contributed to the diversification of vehicle technologies, resulting in the increasing complexity of typical vehicles that make up a fleet. In order to investigate the real gas emissions of different typical vehicles, tests were conducted using a portable emission measurement system (PEMS) in Beijing and emission studies were conducted on eight light-duty passenger vehicles (LDPVs, including light-duty gasoline passenger vehicles and hybrid electric vehicles), eight heavy-duty passenger vehicles (HDPVs), and four light-duty trucks (LDTs). The results show that the emissions of relevant pollutants from LDPV meet the emission standard limits. The emission factors of CO2, CO, NOX, and HC of China IV and China V hybrid electric vehicles (HEVs) are much smaller than the emission standard limits and the emission factors of other vehicles, which have better emission reduction effects. Among LDPV, heavy-duty passenger vehicles (HDPVs), and LDT, the emissions of HDPV and LDT are extremely high. Emission characteristics vary on different types of roads, with the highest emission factors generally occurring on secondary roads. The micro-trip method was used to explore the influence of speed on emission factors. HEV are less sensitive to speed changes and can still maintain a low emission level at low speeds. The average speed and emission factors of HDPV in micro-trip has a strong correlation. Full article
(This article belongs to the Special Issue Vehicle Emissions: New Challenges and Potential Solutions)
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12 pages, 2468 KiB  
Article
Heavy Metal Content in the Soil along the Road No. 7 near Chyżne
by Joanna Korzeniowska
Atmosphere 2023, 14(1), 2; https://doi.org/10.3390/atmos14010002 - 20 Dec 2022
Cited by 3 | Viewed by 1470
Abstract
The aim of the study was to determine the content of heavy metals (Cr, Cu, Ni, Pb, and Zn) in the soil near Road No. 7, near Chyżne. Soil samples were collected in 12 transects (locations) on the east (downwind) and west (upwind) [...] Read more.
The aim of the study was to determine the content of heavy metals (Cr, Cu, Ni, Pb, and Zn) in the soil near Road No. 7, near Chyżne. Soil samples were collected in 12 transects (locations) on the east (downwind) and west (upwind) sides of the road. The samples were taken at a distance of: 5, 50, 100, 300, 500, and 600 m from the edge of the road. Six transects were located in the open area, and another six in the forest. The zinc content in the soil was the highest while that of copper was the lowest. Cr, Cu, Ni, Pb, and Zn concentrations decreased with increasing distance from the road. Differences in the concentration of metals in the soil on the upwind and downwind sides were found. The contents of all tested metals in the soil were higher on the downwind side of the road compared to the concentrations of metals on the upwind side. Full article
(This article belongs to the Special Issue Vehicle Emissions: New Challenges and Potential Solutions)
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18 pages, 3964 KiB  
Article
Ultra-Fine Particle Emissions Characterization and Reduction Technologies in a NG Heavy Duty Engine
by Pierpaolo Napolitano, Davide Di Domenico, Dario Di Maio, Chiara Guido and Stefano Golini
Atmosphere 2022, 13(11), 1919; https://doi.org/10.3390/atmos13111919 - 18 Nov 2022
Cited by 4 | Viewed by 2184
Abstract
This paper describes some strategies to deal with the arduous challenge of reducing emissions from the transport sector. Two different approaches in particle emissions reduction from natural gas (NG) heavy duty (HD) engines were evaluated. The focus was on reducing the ultra-fine sub [...] Read more.
This paper describes some strategies to deal with the arduous challenge of reducing emissions from the transport sector. Two different approaches in particle emissions reduction from natural gas (NG) heavy duty (HD) engines were evaluated. The focus was on reducing the ultra-fine sub 23 nm particles, a key aspect in the vehicles’ impact on human health and environment. To this end, an experimental research activity was carried out on a NG HD engine that was EURO VI regulation compliant. Lubricant oils characterized by different base compositions and ash contents were compared to provide a preferred path to develop formulations. The performed activity on world harmonized transient cycles (WHTCs) have demonstrated a high reduction potential (≈70%) that is reachable by acting on the lube formulation. A CNG particle filter (CPF), derived from the diesel and gasoline engines technology, was fully characterized in terms of its filtration efficiency. Three different types of tests were carried out: steady state, WHTCs, and several idle-to-load step maneuvers. The CPF was highly efficient in reducing solid particles over 10 nm diameter in all the different tests. During WHTCs, the mean abatement efficiency was about 85%. Both technologies provide interesting insights to make NG HD engines compliant with the upcoming Euro VII regulation. Full article
(This article belongs to the Special Issue Vehicle Emissions: New Challenges and Potential Solutions)
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17 pages, 2478 KiB  
Article
Impact of Material on Response and Calibration of Particle Number Systems
by Barouch Giechaskiel and Anastasios Melas
Atmosphere 2022, 13(11), 1770; https://doi.org/10.3390/atmos13111770 - 27 Oct 2022
Cited by 4 | Viewed by 1700
Abstract
In Europe and Asia, vehicle emissions regulations include a number limit for particles larger than 23 nm, which might be reduced to 10 nm in the future. A particle number system (LABS) consists of a volatile particle remover (VPR) and a particle number [...] Read more.
In Europe and Asia, vehicle emissions regulations include a number limit for particles larger than 23 nm, which might be reduced to 10 nm in the future. A particle number system (LABS) consists of a volatile particle remover (VPR) and a particle number counter (PNC). However, it is not simple to derive the combined penetration (efficiency), because the parts are calibrated separately at different sizes and with different materials. On the other hand, portable emissions measurement systems (PEMS) for real-driving emissions (RDE) testing or counters for periodical technical inspection (PTI) of vehicle exhaust are calibrated as complete units with soot-like aerosol. The aim of this study is to estimate the efficiency of a LABS using different materials (soot, graphite, salt, silver, emery oil), typically used for the calibration of LABS, PEMS or PTI counters. The results show that appropriate selection of the calibration material is important in order to have representative of the reality efficiencies. The impact is very high for 23 nm systems, but less critical for 10 nm systems. The estimation of a mean size based on the ratio of 23 nm and 10 nm measurements and the correction of the losses in the sub-23 nm region are also discussed. Full article
(This article belongs to the Special Issue Vehicle Emissions: New Challenges and Potential Solutions)
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12 pages, 2657 KiB  
Article
Impact of Illegal Application of Urea Regulator on Real-World Exhaust Nitrogen Oxygen and Particle Number Emissions
by Jingyuan Li, Maodong Fang, Zhiwen Yang, Zongyan Lv, Ning Wei, Fuwu Yan and Hongjun Mao
Atmosphere 2022, 13(10), 1739; https://doi.org/10.3390/atmos13101739 - 21 Oct 2022
Viewed by 1482
Abstract
Urea regulators (UR) have generally been employed against diesel trucks to save urea usage and thus contribute to the reduction in excessive emissions, while their usage is generally difficult to supervise and enforce. By conducting real driving emission measurements on a China IV [...] Read more.
Urea regulators (UR) have generally been employed against diesel trucks to save urea usage and thus contribute to the reduction in excessive emissions, while their usage is generally difficult to supervise and enforce. By conducting real driving emission measurements on a China IV heavy-duty diesel truck, a “trade-off” effect caused by UR was found between nitrogen oxides (NOx) and particle number (PN) emissions. The usage of UR contributes to 1.04 times higher NOx but 0.28 times lower PN emissions for the whole trip. In particular, the increasing effects on NOx are most efficient on the highway and least effectual on the urban road, while the decreasing effects on PN exhibit an opposite trend under different road types. From low- and medium- to the high-speed bin, the peak average vehicle-specific power NOx emission rates exhibit markedly increasing but slightly decreasing trends for the truck with and without UR, respectively. Furthermore, the NOx emissions in units of CO2 and the linear correlational relationship between CO2 and NOx instantaneous mass emission rates, especially those on the highway, are significantly enhanced. This study directly clarifies the effects of UR on real-world emissions, providing a scientific basis for the real-time identification of the malfunction of the selective catalytic reduction system. Full article
(This article belongs to the Special Issue Vehicle Emissions: New Challenges and Potential Solutions)
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10 pages, 3152 KiB  
Article
Airborne Wear Particles from Dry Clutches
by Rikard Hjelm, Jens Wahlström, Isa Yenibayrak, Driton Sabani, Paula Runsten and Yezhe Lyu
Atmosphere 2022, 13(10), 1700; https://doi.org/10.3390/atmos13101700 - 17 Oct 2022
Cited by 3 | Viewed by 1859
Abstract
A significant part of non-exhaust particle emissions in cities comes from the wear of vehicle components. Several studies on airborne particles from the wear of disc brakes and tires have been completed. However, few publications can be found in the scientific literature regarding [...] Read more.
A significant part of non-exhaust particle emissions in cities comes from the wear of vehicle components. Several studies on airborne particles from the wear of disc brakes and tires have been completed. However, few publications can be found in the scientific literature regarding airborne emissions from dry clutches used in road vehicles. With this in mind, this preliminary study designs a clutch tribometer for the generation of airborne wear particles in a controlled environment. The number concentration and the size distribution of airborne wear particles generated from a typical dry clutch used in passenger cars are investigated. The tests are run at a constant rotational speed, and normal load. The results show that the particle number concentration from dry clutches exhibits a running-in period and a steady state, similar to the particle emissions from disc brake contact. A significant number of nanoparticles (aerodynamic diameter < 100 nm) are emitted from the dry clutch contact. Full article
(This article belongs to the Special Issue Vehicle Emissions: New Challenges and Potential Solutions)
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22 pages, 4205 KiB  
Article
Evaluation of Advanced Diesel Particulate Filter Concepts for Post Euro VI Heavy-Duty Diesel Applications
by Athanasios Mamakos, Dominik Rose, Marc C. Besch, Suhao He, Roberto Gioria, Anastasios Melas, Ricardo Suarez-Bertoa and Barouch Giechaskiel
Atmosphere 2022, 13(10), 1682; https://doi.org/10.3390/atmos13101682 - 14 Oct 2022
Cited by 8 | Viewed by 2440
Abstract
The European Commission (EC) is in the process of finalizing the proposal for the upcoming legislative stage for light- and heavy-duty vehicles. The emission performance over extended operating conditions is under consideration. Furthermore, a tightening of the Solid Particle Number (SPN) limits with [...] Read more.
The European Commission (EC) is in the process of finalizing the proposal for the upcoming legislative stage for light- and heavy-duty vehicles. The emission performance over extended operating conditions is under consideration. Furthermore, a tightening of the Solid Particle Number (SPN) limits with a parallel shift of the lowest detectable size from 23 to 10 nm has been suggested. This paper investigates the SPN emission performance of a Euro VI step E HDV and the potential offered by an advanced Diesel Particulate Filter (DPF) to meet the upcoming regulations. Cold start emissions at clean DPF state were found to be as high as 1.3 × 1012 #/kWh, while passive regeneration events could lead to hot start emissions of 3 × 1011 #/kWh. Improvements in the filtration efficiencies at clean state, similar to those offered by the advanced DPF (>99%), will be needed to tackle these operating conditions. The measurements also revealed the formation of 10 nm SPN in the Selective Catalytic Reduction (SCR) system, at a rate of ~1.2 × 1011 #/kWh. These levels lie above the proposed limit of 1011 #/kWh, highlighting the need to also control these non-volatile nanosized particles. Full article
(This article belongs to the Special Issue Vehicle Emissions: New Challenges and Potential Solutions)
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21 pages, 3161 KiB  
Article
Emissions from a Modern Euro 6d Diesel Plug-In Hybrid
by Tommaso Selleri, Anastasios Melas, Christian Ferrarese, Jacopo Franzetti, Barouch Giechaskiel and Ricardo Suarez-Bertoa
Atmosphere 2022, 13(8), 1175; https://doi.org/10.3390/atmos13081175 - 25 Jul 2022
Cited by 9 | Viewed by 1804
Abstract
Plug-in hybrid electric vehicles (PHEVs) are promoted as an alternative to conventional vehicles to meet European decarbonisation and air quality targets. However, several studies have shown that gasoline PHEVs present similar criteria and particulate emissions as their conventional gasoline counterparts. In the present [...] Read more.
Plug-in hybrid electric vehicles (PHEVs) are promoted as an alternative to conventional vehicles to meet European decarbonisation and air quality targets. However, several studies have shown that gasoline PHEVs present similar criteria and particulate emissions as their conventional gasoline counterparts. In the present work, we investigate the environmental performance of a modern plug-in hybrid Diesel-fuelled vehicle meeting the Euro 6d standard under a large variety of driving patterns, ambient temperatures, and battery states of charge (SOC). Emissions of regulated pollutants, currently unregulated pollutants, and CO2 were measured in the laboratory and following various on-road routes. The vehicle, whose electric range was 82 km, presented emissions below the Euro 6 regulatory limits in all the different driving cycles performed at 23 °C and all the on-road tests at the different battery SOC. The emissions were lower than the average of the conventional Diesel vehicles tested at JRC in 2020–2021 for all the SOC tested, the exception being solid particle number emissions >23 nm (SPN23) emissions that were comparable at all SOC. Moreover, the emissions obtained with the high voltage battery fully charged during on-road tests were comparable to those obtained with the battery at the minimum SOC for the entire test (ca. 91 km) as well as for the urban section (ca. 36 km). Overall, NOx and SPN23 emissions increased at lower temperatures, showing that at very low temperatures, there is no benefit in terms of particulate emissions from the electric range. Finally, it is shown that the emissions of N2O, the only unregulated pollutant presenting relevant emissions for this vehicle, and which are of catalytic nature, were proportional to the utilisation of the internal combustion engine. The scope of the manuscript is thus to deepen the knowledge on the emission performances of Diesel PHEVs through the systematic testing of a modern representative of this class of vehicles in a wide range of driving and environmental conditions. Full article
(This article belongs to the Special Issue Vehicle Emissions: New Challenges and Potential Solutions)
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