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Developments for Future EU7 Regulations and the path to Zero Impact Emissions – A Catalyst Substrate and Filter supplier's perspective
Abstract
New EU7 emission standards are currently under development. While the timing and exact level of stringency of these standards is not available, both OEMs and suppliers are preparing to meet significantly reduced tailpipe NOx and particle number standards for both light- and heavy-duty vehicles. We present here some of the emission control systems that are likely to be implemented and details on the advanced component technologies.
... Thus, most road transport is still powered by internal combustion engines, which primarily run on liquid fuels derived from petroleum and their blends with biofuels. It should be noted that hybrid electric vehicles also utilize internal combustion engines, so they still need to comply with the current emission limits in terms of harmful gaseous pollutants emissions [8,9]. The main measures taken by the automotive manufacturers in their efforts to address the further reduction of gaseous emissions are a combination of measures in the engine and the powertrain, along with the development of suitable exhaust after-treatment systems [1,[9][10][11][12]. ...
... It should be noted that hybrid electric vehicles also utilize internal combustion engines, so they still need to comply with the current emission limits in terms of harmful gaseous pollutants emissions [8,9]. The main measures taken by the automotive manufacturers in their efforts to address the further reduction of gaseous emissions are a combination of measures in the engine and the powertrain, along with the development of suitable exhaust after-treatment systems [1,[9][10][11][12]. Concerning the latter, three-way catalysts (TWC) have been used for several decades in spark-ignited vehicles (fueled with gasoline, natural gas, Liquified Petroleum Gas (LPG)) in order to reduce gaseous emissions. ...
Strict gaseous emission standards are applied globally to regulate the maximum amounts of pollutant emissions that can be produced from all vehicles. The exhaust aftertreatment systems used by automotive manufacturers rely on the utilization of precious metals (Pt, Pd, Rh). However, much effort has been devoted on the reduction or the replacement of the amount of Platinum Group Metals (PGMs) in three-way catalysts (TWC), both from a cost-effectiveness as well as an environmental point of view. PROMETHEUS catalyst, which was recently homologated for Euro 6 applications, is a low-cost, Cu-based TWC, which consists of a significantly lower quantity of PGMs compared to conventional state-of-the-art catalysts and achieves similar or even better catalytic efficiencies. In this review paper, a complex reaction scheme is proposed for the first time for a catalytic converter utilizing Cu and PGMs, following an extensive literature investigation of the available models. The scheme also accounts for the surface reaction mechanisms of the main processes and the side reactions potentially taking place during the TWC operation in the presence of Cu and at least one of the following PGMs: Pt, Pd or Rh. At a next step, the proposed reaction scheme will be validated based on experimental data, using mathematical modelling of a PROMETHEUS catalytic converter incorporating Cu and PGM nanoparticles.
... These strategies include optimizing fuel injection [9] and air management systems [10], using pre-chamber devices [11], introducing innovative piston geometries [12], and applying zero-dimensional models of the combustion process [13] to reduce pollutant formation. Despite the success of these measures in lowering emissions, stringent emission thresholds necessitate the use of advanced aftertreatment systems (ATS) to meet regulatory limits before exhaust gases are released into the environment [14]. Furthermore, the industry is exploring using low-carbon and cleaner-burning alternative fuels like ethanol, methanol, and LPG [15], with a special interest in carbonfree fuels like hydrogen [16]. ...
... The current standard employed in Europe to regulate emissions of heavy-duty (HD) engines is the Euro VI, and one version of Euro VII has been proposed recently [14]. Euro VII implementation will have aspects designed to make current limits for allowed levels of CO, UHC, and NOx emission more restrictive, implementing NH3 and N2O regulations in specific emissions and keeping the limit for PN emission, but assessing them from particles larger than 10 nm [11]. ...
This study aims to examine the particle number (PN) emissions of a retrofitted heavy-duty spark ignition (HD-SI) engine powered by liquefied petroleum gas (LPG) under both steady-state and transient conditions. The engine was tested under seven steady-state operating points to investigate the PN behavior and particle size distribution (PSD) upstream and downstream of the three-way catalyst (TWC). This analysis intends to assess the impact of including particles with diameters ranging from 10 nm to 23 nm on the total particle count, a consideration for future regulations. The study employed the World Harmonized Transient Cycle (WHTC) for transient conditions to encompass the same engine working region as is used in the steady-state analysis. A Dekati FPS-4000 diluted the exhaust sample to measure the PSD and PN for particle diameters between 5.6 nm and 560 nm using the TSI-Engine Exhaust Particle Sizer (EEPS) 3090. The findings indicate that PN levels tend to increase downstream of the TWC under steady-state conditions in operating points with low exhaust gas temperatures and flows (equal to or less than 500 °C and 120 kg/h). Furthermore, the inclusion of particles with diameters between 10 nm and 23 nm leads to an increase in PN emissions by 17.70% to 40.84% under steady conditions and by an average of 40.06% under transient conditions, compared to measurements that only consider particles larger than 23 nm. Notably, in transient conditions, most PN emissions occur during the final 600 s of the cycle, linked to the most intense phase of the WHTC.
... It is expected that new, increasingly stringent emission standards will influence vehicle manufacturers to design and implement increasingly sophisticated and effective exhaust cleaning systems [6]. Taking into account that many issues regarding "zero emission" transport are still unresolved (e.g. ...
... Taking into account that many issues regarding "zero emission" transport are still unresolved (e.g. related to the availability and distribution of CO 2 -free electricity, charging infrastructure for electric vehicles in cities, sourcing of raw materials for battery production), vehicles using combustion engines will continue to be produced and sold in the form of hybrid drive systems, which consume less fuel and therefore have lower emissions of pollutants into the atmosphere [6,31]. ...
The article attempts to analyze the possible effects of using Ti−C:H DLC carbon coatings produced by pulsed magnetron sputtering (PVD) to reduce friction coefficient and wear in kinematic pairs found in internal combustion engines and powertrain systems used in automotive vehicles. The aim of such action is primarily to reduce internal losses in the aforementioned units. The coatings were deposited on heat-treated bearing steel 100Cr6, examined using a scanning electron microscope FEI Quanta 200 Mark II with the chemical analyzer EDS EDAX Genesis XM 2i, tribotester T−01M examining the friction coefficient in the ball-disc correlation and Hommel Werke T8000 profilometers, additionally, in order to check the coating thickness, studies were carried out using the Calotest method. The results obtained indicate that both the friction coefficient and wear are drastically reduced in relation to samples on which no DLC coatings were applied.
... At cold start at − 7 • C (a) it takes more than 500 s before emissions similar to those emitted at hot start test are seen. That is why for the cold start the acceleration of the catalyst heat-up may be essential to meet the NOx Euro 7 limits (Boger et al., 2022). Aftertreatment systems such as exhaust gas heaters (Ximinis et al., 2022a), electrically heated catalyst (EHC) (Mendoza Villafuerte et al., 2022) and Thermoelectric Aftertreatment Heater (TATH), have been shown to reduce NOx emissions for the cold start below proposed Euro 7 limits. ...
... It is clear that improvements in the aftertreatment system are required, not only for cold start conditions, but also for hot conditions, especially at low ambient temperatures, potentially necessitating the adoption of new aftertreatment system architectures such as those presented by Selleri et al. (Selleri et al., 2022a), Boger et al. (Boger et al., 2022) and tested by Mendoza Villafuerte et al. (Mendoza Villafuerte et al., 2022). Furthermore, behaviours such as the ones observed during the − 7 • C (b) test are what is expected to be avoided with the Euro 7 proposal, by guaranteeing that the aftertreatment system operates even when a vehicle operates over extended driving conditions and ambient temperature ranges (i.e., from − 10 to − 7 • C and from 35 to 45 • C), unless a technical justification is sanctioned by the type approval authority. ...
... The particle count filtration efficiency (PCFE) of the investigated GPFs (and 4WCs) is considerably lower than the PCFE of the DPFs studied. (This drawback has recently been addressed, and new filter substrates for GPFs are available that produce the same high-quality PCFEs as the DPFs [55].) • ...
Particle number concentration (PN) in vehicle exhaust and ambient air describes the number of ultrafine particles (UFPs) below 500 nm, which are recognized as a toxic and carcinogenic component of pollution and are regulated in several countries. Metal nuclei, ash, and organic matter contribute significantly to the ultrafine particle size fraction and, thus, to the particle number concentration. Exhaust gas filtration is increasingly being used worldwide to significantly reduce this pollution, both on diesel particulate filter (DPF) and gasoline particulate filter (GPF) engines. In recent years, the EU has also funded research projects dealing with the possibilities of retrofitting gasoline vehicles with GPFs. This paper presents the results and compares the PN emissions of different vehicles. An original equipment manufacturer (OEM) diesel car with a DPF is considered as a benchmark. The PN emissions of this car are compared with a CNG car without filtration and with gasoline cars equipped with GPFs. It can be concluded that the currently used GPFs still have some potential to improve their filtration efficiency and that a modern CNG car would still have remarkable possibilities to reduce PN emissions with an improved quality GPF.
... Compared to conventional calibration, in which a fixed test cycle was focused strongly, RDE tests offer a high variance, which further increases the requirements for a robust calibration as well as hardware and exhaust aftertreatment (EATS) design [7]. Thus, the analysis of different scenarios is of particular importance. ...
The systematic analysis of measurement data allows a large amount of information to be obtained from existing measurements in a short period of time. Especially in vehicle development, many measurements are performed, and large amounts of data are collected in the process of emission calibration. With the introduction of Real Driving Emissions Tests, the need for targeted analysis for efficient and robust calibration of a vehicle has further increased. With countless possible test scenarios, test-by-test analysis is no longer possible with the current state-of-the-art in calibration, as it takes too much time and can disregard relevant data when analyzed manually. In this article, therefore, a methodology is presented that automatically analyzes exhaust measurement data in the context of emission calibration and identifies emission-related critical sequences. For this purpose, moving analyzing windows are used, which evaluate the exhaust emissions in each sample of the measurement. The detected events are stored in tabular form and are particularly suitable for condensing the collected measurement data to a required amount for optimization purposes. It is shown how different window settings influence the amount and duration of detected events. With the example used, a total amount of 454 events can be identified from 60 measurements, reducing 184,623 s of measurements to a relevant amount of 12,823 s.
... These strategies include optimizing fuel injection [6] and air management systems [7], using pre-chamber devices [8], and introducing innovative piston geometries [9] to reduce pollutant formation. Despite the success of 2 these measures in lowering emissions, stringent emission thresholds necessitate the use of advanced Aftertreatment Systems (ATS) [10] to meet regulatory limits before exhaust gases are released into the environment. Furthermore, the industry is exploring using low-carbon and cleaner-burning alternative fuels [11] and is interested in carbon-free fuels like hydrogen [12]. ...
This study aims to examine the non-volatile Particle Number (PN) emissions of a retrofitted Heavy-Duty Spark-Ignition (HD-SI) engine powered by liquefied petroleum gas (LPG) under both steady-state and transient conditions. The engine was tested under seven steady-state operating points to investigate the PN behavior and Particle Size Distribution (PSD) upstream and down-stream of the Three-Way Catalyst (TWC). This analysis intends to assess the impact of including particles with diameters ranging from 10 nm to 23 nm in the total particle count, a consideration for future regulations. The study employed the World Harmonized Transient Cycle (WHTC) for transient conditions to encompass the same engine working region used in the steady-state analysis. A Dekati FPS-4000 diluted the exhaust sample to measure the PSD and PN for particle diameters between 5.6 nm and 560 nm using the TSI-Engine Exhaust Particle Sizer (EEPS) 3090. Findings indicate that PN levels tend to increase downstream of the TWC under steady-state conditions in operating points with low exhaust gas temperatures and flows (equal to or less than 500 °C and 120 kg/h). Furthermore, the inclusion of particles with diameters between 10 nm and 23 nm leads to an increase in PN emissions by 17.70% to 40.84% under steady conditions and by an average of 40.06% under transient conditions, compared to measurements that only consider particles larger than 23 nm. Notably, in transient conditions, most PN emissions occur during the final 600 seconds of the cycle, linked to the most intense phase of the WHTC.
... State of the art strategies ensuring RDE compliance have also been developed to cope with the broad and comprehensive test matrix required to effectively cover all possible RDE scenarios [14][15][16][17]. Hence, the ultimate goal is the zero impact emission vehicle, such as investigated by Maurer et al. and Boger et al. [1,18]. ...
With the Euro 7 pollutant emission legislation currently under discussion, advanced and more efficient exhaust aftertreatment systems are being developed. The technologies required for these are leading to an increase in the number of components and control systems requiring diagnoses strategies under the on-board diagnostics (OBD) legislation. With concurrent shorter development times and significant reductions in budgets allocated to conventional powertrain development, challenges in the field of OBD calibration and verification are already rising sharply. In response to these challenges, hardware-in-the-loop (HiL) approaches have been successfully introduced to support and replace conventional development methods. The use of complex simulation models significantly improves the quality of calibrations while minimizing the number of required prototype vehicles and test resources, thus reducing development costs. This paper presents a feasibility study for moving OBD-related calibration and validation tasks from the vehicle to a HiL platform. In this context, the calibration and verification process of an active diagnostic for monitoring the condition of the three-way catalyst (TWC) and the oxygen sensors in the exhaust aftertreatment system is presented. It is shown that all relevant signals are simulated with sufficient accuracy to ensure a robust transfer from the vehicle to a HiL test bench. Special attention is given to the simulation of aged components and their influence on the emission behavior of the system. Furthermore, it is discussed that transferring OBD tasks from the vehicle to the HiL test bench could result in significant savings in development time and a reduction in the number of physical prototype vehicles and test resources required.
... The trend and direction of vehicle development are influenced by a reduction in energy and fuel consumption, as well as the optimization of the overall system with the aim of producing zero-impact emission vehicles [2,3]. Furthermore, legislation continues to drive this change by adjusting emission regulations [4,5]. ...
Further reducing greenhouse gas and pollutant emissions from road vehicles is a major task for the automotive industry. Stricter regulations regarding emissions and fleet fuel consumption require the continuous development of new powertrains and methods. In particular, the combination of hybrid powertrains on the technical side and the focus on real driving emissions (RDE) on the legislative side pose significant challenges to the vehicle calibration process. Against this background, new test methods and environments are being investigated to counteract the high number of interactions between hybrid drive systems and quasi-infinite test conditions due to RDE. Complementary to new test environments, innovative methods for data analysis are needed that allow the exploitation of the complete potential of measurement data. The application of such a method in the field of emission calibration is presented in this paper. For this purpose, a clustering method (HDBSCAN) is applied to critical sequences from emission tests. Within this presentation, the clustering process is based on a single signal only. This paper shows how signals of various characteristics can be processed with dynamic time warping and generically structured with the clustering method used. Here, 959 single events are automatically categorized into 24 clusters. This provides a new basis for system evaluation, enabling the automatic identification, categorization, and prioritization of calibration weaknesses. Using twelve signals of different characteristics, the generic usability of the clustering method is demonstrated.
... In order to avoid the unintentional release of ammonia into the environment, e.g., from leaks within pipes, the use of appropriate sensors to detect gaseous ammonia is essential and will also be required by legislation in the future [7,8]. The Euro 7 standard for vehicles dictates a new emission limit of 10 mg/km for ammonia as of 2025 [9]. However, suitable sensors for ammonia detection are rarely available for applications in high-temperature processes [10]. ...
The selective detection of different gas components will remain of huge importance in the future, either in the ambient air or in flue gases, e.g., for controlling purposes of combustion processes. The focus here is on the development of a highly selective ammonia sensor that will be exemplarily used in the flue gas of biomass combustion plants with catalysts for nitrogen oxide reduction. Such applications require a robust sensor design, in this case, based on a ceramic substrate. The gaseous ammonia is detected with the help of a zeolite film, whose selective adsorption properties towards ammonia are already intensively being used in the field of flue gas catalysis. The adsorption and desorption of ammonia on the gas-sensitive zeolite film lead to changes in the dielectric properties of the functional material. Using an interdigital electrode (IDE) structure below the zeolite film, the capacitance was determined as a measure of the ammonia concentration in the gas. In this context, the fabrication of all layers of the sensor in the thick film with subsequent laser patterning of the IDE structure enables a cost-efficient and effective method. The functionality of this sensor principle was extensively tested during measurements in the laboratory. A high and fast response to ammonia was detected at different sensor temperatures. In addition, very low cross-sensitivities to other gas components such as water (very low) and oxygen (zero) were found.
... The new Euro 7 Emission Standards [1] will be adopted by many countries in the world, including Japan. They will require stricter regulations on car emissions, particularly focusing on reducing particulate matter (PM) levels, including particle mass (PMs) and particle numbers (PNs) [2]. In the current gasoline after-treatment systems, the primary device used to capture PM is a gasoline particulate filter (GPF). ...
A granular substrate used as a support for a three-way catalyzed (TWC) solid-particle membrane filter was investigated through numerical simulation. The proposed support could reduce the amount of required catalyst material by 39% and lower the pressure drop by 33%, compared to a conventional filter, while achieving almost 100% soot-filtration. Moreover, TWC porous particles, which are designed to introduce a fluid flow into their interconnected pore network, further decrease the pressure drop. However, a trade-off exists between the amount of the introduced fluid flow and the specific surface area.
... The constant need to optimize modern passenger cars in terms of sustainability, price, emission reduction [1,2], and quality places high demands on the development processes [3][4][5]. Constantly updated and intensified emission standards, such as the Euro 6d introduced in 2017 [6,7] or the upcoming Euro 7 regulations [8], set new framework conditions specifically for the series calibration process of modern vehicles [9][10][11]. To ensure legal compliance under all relevant conditions and to increase the efficiency in daily use, topics such as base calibration, drivability calibration, emission calibration, or operating strategy calibration are using new approaches in their daily processes in order to achieve zero-impact emission vehicles [2,[12][13][14]. ...
The topics of climate change and pollutant emission reduction are dominating societal discussions in many areas. In automotive development, with the introduction of real driving emissions (RDE) testing and the upcoming EU7 legislation, there are endless boundary conditions and potential scenarios that need to be evaluated. In terms of vehicle calibration, this is leading to a strong focus on alternative approaches such as virtual calibration. Due to the flexibility of virtual test environments and the variety of RDE scenarios, the amount of data collected is rapidly increasing. Supporting the calibration engineers in using the available data and identifying relevant information and test scenarios requires efficient approaches to data analysis. This paper therefore discusses the potential of data clustering to support this process. Using a previously developed approach for event detection in emission calibration, a methodology for the automatic categorization of events is presented. Approaches to clustering algorithms (hierarchical, partitioning, and density-based) are discussed and applied to data of interest. Their suitability for different signals is investigated exemplarily, and the relevant inputs are analyzed for their usability in calibration procedures. It is shown which clustering approaches have the potential to be implemented in the vehicle calibration process to provide added value to data evaluation by calibration engineers.
... In order to meet upcoming stringent emission legislations (e.g., Euro 7 or CARB 2024), near-zero tailpipe NOx levels are required even during engine cold start and low load operations [3,4] when a traditional SCR will not be active. In highly efficient modern diesel engines, the exhaust temperature can be below 150 • C during low load driving, which will require additional heating measures (such as an electrical catalyst heater or a diesel burner) upstream of the diesel oxidation catalyst in order to meet the future Euro 7 regulations [5]. Various LTC approaches have been investigated to reduce NOx and soot simultaneously at low and intermediate load operating conditions. ...
Using high charge dilution low temperature combustion (LTC) strategies in a diesel engine offers low emissions of nitrogen oxides (NOx). These strategies are limited to part-load conditions and involve high levels of charge dilution, typically achieved through the use of recirculated exhaust gases (EGR). The slow response of the gas handling system, compared to load demand and fuelling, can lead to conditions where dilution levels are higher or lower than expected, impacting emissions and combustion stability. This article reports on the sensitivity of high-dilution LTC to variations in EGR rate and fuel injection timing. Impacts on engine efficiency, combustion stability and emissions are assessed in a single-cylinder engine and compared to in-cylinder flame temperatures measured using a borescope-based two-colour pyrometer. The work focuses on low-load conditions (300 kPa gross indicated mean effective pressure) and includes an EGR sweep from conventional diesel mode to high-dilution LTC, and sensitivity studies investigating the effects of variations in charge dilution and fuel injection timing at the high-dilution LTC condition. Key findings from the study include that the peak flame temperature decreased from ~2580 K in conventional diesel combustion with no EGR to 1800 K in LTC with low-NOx, low-soot operation and an EGR rate of 57%. Increasing the EGR to 64% reduced flame temperatures to 1400 K but increased total hydrocarbon (THC) and carbon monoxide (CO) emissions by 30–50% and increased fuel consumption by 5–7%. Charge dilution was found to have a stronger effect on the combustion process than the diesel injection timing under these LTC conditions. Advancing fuel injection timings at increasing dilution kept combustion instability below 2.5%. Peak in-cylinder temperatures were maintained in the 2000–2100 K range, while THC and CO emissions were controlled by delaying the onset of bulk quenching. Very early injection (earlier than 24 °CA before top-dead-centre) resulted in spray impingement on the piston crown, resulting in degraded efficiency and higher emissions. The results of this study demonstrate the potential of fuel injection timing modification to accommodate variations in charge dilution rates while maintaining low NOx and PM emissions in a diesel engine using low-temperature combustion strategies at part loads.
... Concerns for existence of non-volatile particles below 23 nm for vehicles led to investigations and expansion of the vehicle emissions regulation protocol down to 10 nm [4]. The new methodology, included in the global technical regulation (GTR 15), is not part of any vehicle regulation yet, but there are discussions on-going to include them in the next EU regulatory step (Euro 7) for both light-duty and heavy-duty vehicles [5][6][7][8]. ...
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.
... Increased urea dosing might also be required, which will also lead to high particle number emissions. A second DPF at the end of the tailpipe seems a viable solution, as it was recently demonstrated [51,52]. The increased N 2 O emissions from the DOC, SCR, and ASC need optimization of the catalyst materials and formulations, system architecture, and the operating strategies, as its subsequent removal is challenging [53,54]. ...
The latest generation of heavy-duty vehicles (Euro VI step E) have to respect low emission
limits both in the laboratory and on the road. The most challenging pollutants for diesel vehicles are NOx and particles; nevertheless, NH3 and N2O need attention. In this study, we measured regulated and unregulated pollutants of a Euro VI step E Diesel vehicle. Samples were taken downstream of (i) the engine, (ii) the Diesel oxidation catalyst (DOC) and catalyzed Diesel particulate filter (cDPF), and (iii) the selective catalytic reduction (SCR) unit for NOx with an ammonia slip catalyst (ASC). In addition to typical laboratory and real-world cycles, various challenging tests were conducted (urban driving with low payload, high-speed full-load driving, and idling) at 23 C and 5 C. The results showed high efficiencies of the DOC, DPF, and SCR under most testing conditions. Cold start cycles
resulted in high NOx emissions, while high-temperature cycles resulted in high particle emissions. The main message of this study is that further improvements are necessary, also considering possible reductions in the emission limits in future EU regulations.
The research aims to analyze the effect of the primary pulley slope angle on engine torque and fuel consumption of the Mio Sporty 115 CC motorbike. The inclination angle of the primary pulley based on factory standards is 14º. Changing the slope angle of the primary pulley using a lathe for angles of 12º, 13º and 13.5º. Testing was carried out using a dyno test machine, 3 data for each slope angle. The dyno test results consist of engine speed, torque, and power. Fuel consumption is obtained using calculations based on test data. Based on the analysis of test results and calculations, it is known that the slope angle of the primary pulley affects engine torque and fuel consumption of the Mio Sporty 115 CC motorbike. The 14º slope angle produces 6.35 torque, the 13.5º slope angle produces 6.47, the 13º slope angle produces 6.29 and the 12º slope angle produces 6.02. Meanwhile, for fuel consumption, slope angle 12º and 14º require fuel consumption of 0.19 l/hour, slope angle 13º & 13.5º require fuel consumption of 0.18 l/hour. Based on the highest torque and the lowest fuel consumption results, a slope angle of 13.5º is recommended.
A multi-layer membrane has been fabricated to integrate a Three-Way Catalyst (TWC) and Gasoline Particulate Filter (GPF) into one device, called a four-way catalytic converter. The top layer, made of nano-scale potassium catalyst particles, traps Particulate Matter (PM) with almost 100% filtration efficiency at all times and oxidizes PM (mostly soot) with a significantly reduced temperature of 476°C at the oxidation peak. Moreover, the bottom layer catalyst is comprised of sub-micro TWC particles to combine NO reduction and CO oxidation capabilities. The effective temperature range for the simultaneous removal of all pollutants was between 420°C–500°C.
div class="section abstract"> Options for CNVII emission legislation are being widely investigated in a national program organized by China Vehicle Emission Control Center (VECC) since early 2020. It is foreseen that this possibly last legislation in China will have more stringent emission requirements compared to CNVI, including among other changes especially a further reduction of nitrogen oxide (NOx), inclusion of nitrous oxide (N2O) and sub-23 nm particle number (PN).
This study investigates the technical feasibility to fulfill a CNVII emission legislation scenario, based on a modified CNVI 8 L engine operating under both cold and hot World Harmonized Transient Cycle (WHTC) and Low Load Cycle (LLC). Methods to address the challenges are discussed and validated, including application of a twin dosing system, electric heater, hybrid concepts of combining Copper (Cu-), Iron (Fe-) and Vanadium (V-) SCR technologies, filters with ultra-high filtration efficiency and optimization of engine calibration and urea dosing strategies.
Based on the results, an advanced aftertreatment system is then proposed that can meet the requirements of the discussed CNVII scenario.
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Mitigating CO2 emissions from long-haul commercial trucking is a major challenge that must be addressed to achieve substantial reductions in greenhouse gas (GHG) emissions from the transportation sector. Extensive recent research and development programs have shown how significant near-term reductions in GHGs from commercial vehicles can be achieved by combining technological advances. This paper reviews progress in technology for engine efficiency improvements, vehicle resistance and drag reductions, and the introduction of hybrid electric powertrains in long-haul trucks. The results of vehicle demonstration projects by major vehicle manufacturers have shown peak brake thermal efficiency of 55% in heavy-duty diesel engines and have demonstrated freight efficiency improvements of 150% relative to a 2009 baseline in North America. These improvements have been achieved by combining multiple incremental improvements in both engine and vehicle technologies. Powertrain electrification through hybridization has been shown to offer some potential reductions in fuel consumption. These potential benefits depend on the vehicle use, the details of the powertrain design, and the duty cycle. To date, most papers have focused on standard drive cycles, leaving a research gap in how hybrid electric powertrains would be designed to minimize fuel consumption over real-world drive cycles, which are essential for a reliable powertrain design. The results of this paper suggest that there is no “one-size-fits-all” solution to reduce the GHGs in long-haul trucking, and a combination of technologies is required to provide an optimum solution for each application.
div class="section abstract"> Ultrafine particles, in particular solid sub-100 nm particles pose high risks to human health due to their high lung deposition efficiency, translocation to all organs including the brain and their harmful chemical composition; due to dense traffic, the population in urban environments is exposed to high concentrations of those toxic air contaminants, despite these facts, they are still widely neglected. Therefore, the EU-Commission set up a program for clean and competitive solutions for different problem areas which are regarded to be hotspots of such particles. HORIZON AeroSolfd is an EU project, co-funded by Switzerland that will deliver affordable, adaptable, and sustainable retrofit solutions to reduce exhaust tailpipe emissions from petrol engines, brake emissions and pollution in semi-closed environments. VERT, a Swiss based international industry organization, has a long research history in the field of nanoparticle filtration and it is in charge of reducing tailpipe emissions of gasoline vehicles by using the best available retrofit filtration technology (BAT). VERT will apply the newest high-efficient GPF technology in three high mileage fleets, in Germany, Switzerland and Israel. The project will also serve as a platform to continue research on PN emissions as well as on secondary emissions from GDI and PFI petrol engines. In addition, the “high emitter phenomena” will be further analysed with a NPTI testing campaign of 1000 gasoline vehicles, including GDI, PFI and GPF equipped vehicles.
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In this paper, a new methodology for the definition of the acoustic capacity of a road infrastructure is proposed. The acoustic capacity is rather a new topic as, in the road performance assessment, only the physical capacity is taken into account, or, sometimes, the environmental capacity due to atmospheric pollutants; instead the environmental capacity due to noise, called “acoustic capacity” in the following, is always neglected. For the acoustic capacity assessment, the Harmonoise model has been used: it receives in input traffic data and provides in output noise emission and immission levels which are after compared to the limit levels established by law. Moreover, some problems of implementation on the field of the acoustic capacity methodology are investigated: the position of the receiver in the case of intersections of complex geometry; the noise emission limit values to take into account in case of rush hour traffic. The proposed methodology is applied to a real network: the road network of Piombino, Italy. The results of the application show firstly that the acoustic capacity is actually a constraint involving several traffic flows. Moreover, the acoustic capacity of a road infrastructure is generally lower than its physical capacity, when the noise emission limit value is that imposed by law: that is the acoustic descriptor Lday in our analysis. When the limit value increased by 3 dB(A) for rush hours is taken into account, the acoustic capacity is higher, and is more often greater than the physical capacity.
div class="section abstract"> As the official proposal for emission regulation Euro 7 has been released by European Commission, PN above 10nm is taken into consideration for the ultrafine particulate emissions control. The challenges of GPF filtration efficiency emerge for the light-duty manufactures to meet the future emission standards. In the present study, a China 6 compliant vehicle was tested to reveal its performance over the China 6 standards and potential to meet the upcoming Euro 7. Three GPF product types (Gen 1, Gen 2, and concept Gen 3) were mounted to the tested vehicle. WLTC tests were conducted on chassis dynamometer in laboratory as well as a self-designed aggressive cycle (“Base Cycle”) tests. To explore the GPFs performance for PN emissions above 10nm against the proposed limit 6.0E11 #/km, PN emission above 10nm were measured in our laboratory tests for both engine out and tailpipe as well as the PN emission above 23nm. In addition, worst case RDE tests were carried out on the real road with PEMS. It was found that, when including particles down to 10nm, further improvement is needed for the current system, and the Gen 2 and concept Gen 3 products could be a promising path to meet the proposed standards with much higher filtration efficiency. Combined with possibly further extended RDE boundary conditions in Euro 7, the test results suggested that higher filtration efficiency filter products are likely required to comply with the tightened emission regulations.
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The effect of ambient humidity on the performance and pollutant emissions of internal combustion engines is not considered in the literature despite type-approval criteria are moving closer to real driving conditions. This work analyses experimentally the effects of charge air humidity at high warm altitudes, where the use of exhaust gas recirculation (EGR) is typically lowered and even avoided to recover engine performance at the expense of NOx emissions increase, on the response of a compression-ignition engine under a wide range of steady-state conditions in terms of engine-out emissions and specific fuel consumption. The impact of specific humidity variations within the atmospheric range was analysed by coupling the engine to an altitude simulator with pressure, temperature, and humidity control capabilities. High altitudes and warm & high ambient temperatures were explored (2000 m at 30 °C and 2500 m at 45 °C) to cover ambient specific humidity up to 30 gwater/kgdry_air. In addition, the effects of increasing the specific humidity above the atmospheric levels were considered at 2500 m and 45 °C to emulate forced injection of water in the engine intake line corresponding to 60 gwater/kgdry_air. With this approach, understanding of the role of humidity is provided to highlight its importance as additional ambient property in emission control. In parallel, the assessment of the forced water content increase to control NOx emissions when EGR must be lowered was performed due to the altitude impact on the engine performance and turbocharger limits. The results showed a consistent and significant reduction in engine-out NOx emissions as the ambient humidity increased, reaching up to 300% with respect to the dry case, caused by the decrease in O2 availability due to the water content increase. The benefits of high humidity in NOx emission control at high altitudes when EGR is not feasible were complemented by an improved trade-off with particulate matter emission compared to the standard from EGR use. The results evidenced a reduction in opacity close to 250% for a given engine-out NOx emission when EGR was replaced by water content. By contrast, the slowdown of the combustion process as the fresh air humidity increased deteriorated the specific fuel consumption significantly as the engine load and speed increased. Nevertheless, these penalties ranged from 2 to 2.7% in the worst conditions and showed the same sensitivity for EGR and humidity increases.
The California Air Resources Board and US Environmental Protection Agency have defined their new ultra-low NOx standards for heavy-duty diesel engines (HDDE) over the last two years. In parallel, AVL has continued its research on how to meet these new limits and to address the continuing challenge of cold start emissions from HDDE, including incorporating
• Advanced thermal management strategies to accelerate exhaust aftertreatment system (EAS) warm-up
• Close-coupled selective catalytic reduction (ccSCR) system upstream of the current Euro VI or EPA 2013 EAS
This paper will continue from the presentation at the 2019 CLEERS Workshop and present further developments in the research program including experimental results. These results include the following:
• Measured effects of thermal management strategies on EAS warm-up
• Test results using the ccSCR and “underfloor” SCR in combination
• Strategies for successful ultra-low NOx compliance
• Interactions between ccSCR system and on-board diagnostics (OBD) requirements
AVL recommendations and next steps will also be discussed.
[See https://cleers.org/cleers-workshops/workshop-abstracts/?entry_id=3199]
The transport sector is one of the main sources air pollutants. Different exhaust after-treatment systems have been implemented over the years to control the emissions of criteria pollutants. However, while reducing the emissions of the target compounds these systems can lead to the emissions of other pollutants and/or greenhouse gases such as NH3 or N2O. Following the implementation of the Real Driving Emissions (RDE) test procedure in the EU, vehicles have been equipped with more complex after-treatment configurations. The impact that these technologies may have on the emissions of non-regulated pollutants during real-world driving have not been evaluated until now. In the current study we present the on-road emissions of a series of non-regulated pollutants, including NH3, N2O, CH4 and HCHO, measured with a portable FTIR from a series of Euro 6d, Euro 6c and Euro 6d-TEMP, gasoline diesel and compressed natural gas (CNG) vehicles during real-world testing. The obtained results show that it is possible to measure N2O, NH3, CH4 and HCHO during on-road operation. The results also highlight the importance of the measurement of the emissions of these pollutants during real-world driving, as the emissions of NH3 (a particulate matter precursor) and those of N2O and CH4 (green-house gases) can be high from some vehicle technologies. NH3 emissions were up to 49 mg/km for gasoline passenger cars, up to 69 mg/km for the CNG light-commercial vehicle and up to 17 mg/km a diesel passenger car equipped with a selective catalytic reduction system (SCR). On the other hand, N2O and CH4 emissions accounted for up to 9.8 g CO2 eqv/km for a diesel passenger car equipped with a combination of diesel oxidation catalysts (DOC), lean NOx traps (LNT), SCR and possibly an ammonia slip catalyst ASC.
div class="section abstract"> This review covers advances in regulations and technologies in the past year in the field of vehicular emissions. We cover major developments towards reducing criteria pollutants and greenhouse gas emissions from both light- and heavy-duty vehicles and off-road machinery. To suggest that the transportation is transforming rapidly is an understatement, and many changes have happened already since our review last year [ 1 ]. Notably, the US and Europe revised the CO2 standards for light-duty vehicles and electrification mandates were introduced in various regions of the world. These have accelerated plans to introduce electrified powertrains, which include hybrids and pure electric vehicles. However, a full transformation to electric vehicles and the required grid decarbonization will take time, and policy makers are accordingly also tightening criteria pollutant standards for internal combustion engines. California has published the Advanced Clean Cars II standards and Europe has held various workshops outlining the core elements of future Euro 7 regulations. These will likely be the last major regulations for criteria pollutants, and compliant vehicles will likely be zero-impact emitting, that is with tailpipe emissions at or lower than the ambient concentrations. Meeting these regulations will require adoption of several advanced engine and emission control technologies which we discuss here. Emphasis will be on reducing cold start emissions, likely requiring active thermal management strategies. The challenge will be to lower criteria pollutants while also reducing fuel consumption, and we review some approaches being considered. The story is similar for heavy-duty vehicles, where meeting California’s Low NOx regulations and Euro VII scenarios require significantly improved engine controls and after-treatment systems. New system solutions and hardware additions show a pathway to meeting the regulations, although we caution that much more work is needed ahead to achieve the reductions over extended durability limits and with healthy engineering margins. We also review the impact of alternative fuels on reducing well-to-wheels (WTW) greenhouse gas emissions, along with recommendations to continue improving market fuel quality to reduce negative impact on criteria pollutants. Finally, while this paper does not intend to provide a detailed review of battery electric or fuel cell vehicle technology, we touch upon a few studies which discuss the outlook of powertrain diversification from a total cost of ownership and greenhouse gas reduction perspective.
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div class="section abstract"> Heavy-duty vehicles represent a significant portion of road transport and they need to operate in a clean and efficient manner. Their emission control systems need to be enhanced to sustain the high conversion efficiencies seen during motorway conditions inother operating conditions. The European Commission is developing legislative proposals for Euro 7 emissions regulations for light- and heavy-duty vehicles. The new Euro 7regulation will likely focus on ensuring the emissions from heavy-duty vehicles are minimized over extensive on-road operating conditions and specifically on operating conditions such as urban driving and cold-start operation. These challenges are increased by the need to ensure low secondary emissions like NH3 and N2O, as well as a low impact on CO2 emissions. The paper outlines the low pollutant emissions achieved by a heavy-duty Diesel demonstrator vehicle. The vehicle is equipped with an innovative layout of state-of-the-art emission control technologies, combined with an advanced controlstrategy on an existing Euro VI long-haul truck. The new emissions control system integrates a close-coupled DOC, a catalyzed DPF, dual-SCR system -one in a close-coupled position-, with twin AdBlue® dosing controlled withFEV developed software. Both SCR catalysts contain an ammonia slip catalyst. The innovative system layout allows ultra-low NOx emissions and well controlled secondary emissions in even the most challenging conditions with minimal impact on CO2 emissions. Pollutant emissions were evaluated over a broad range of operating conditions, including different payloads to show the emissions reduction potential. This paper also includes results obtained from the on-road Portable Emissions Measurement System (PEMS) testing.
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div class="section abstract"> With the introduction of EU6d and CN6 all vehicles with gasoline direct injection and many with port fuel injection engine will be equipped with a gasoline particulate filter (GPF). A range of first generation filter technologies has been introduced successfully, helping to significantly reduce the tailpipe particulate number emissions. The continued focus on particulate emissions and the increasing understanding of their impact on human health, combined with the advanced emission regulations under RDE conditions results in the desire for filters with even higher filtration efficiency, especially in the totally fresh state. At the same time, to balance with the requirements on power and CO2, limitations exist with respect to the tolerable pressure drop of filters.
In this paper we will report on a new generation of gasoline particulate filters for uncatalyzed applications. This new generation of filters has been developed to enable very high filtration efficiency, in most cases above 90%, even in the totally fresh state and over aggressive drive cycles. At the same time the associated pressure drop penalty of these new technologies is moderate and under many practical conditions comparable to Gen 1 technologies. The performance of the new filter technology will be discussed based on experimental data obtained on several vehicles and under different emission cycles. The robustness of the new technologies will be assessed based on data generated on engine bench and real world mileage accumulation on public roads.
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div class="section abstract"> Despite considerable progress over the last several decades, California continues to face some of the most significant air quality problems in the United States. These continued issues highlight the need for further mobile source NOX reductions to help California and other areas meet ambient air quality targets mandated by the U.S. EPA. Beginning in 2014, the California Air Resources Board (CARB) launched a program aimed at demonstrating technologies that could enable heavy-duty on-highway engines to reach tailpipe NOX levels up to 90% below the current standards, which were implemented in 2010. At the same time, mandated improvements to greenhouse gas emissions (GHG) require that these NOX reductions be achieved without sacrificing fuel consumption and increasing GHG emissions. The CARB demonstration program has progressed through several stages since it was initiated, and the Stage 3 Low NOX program completed in 2020 represents the culmination of these technology demonstration efforts. This effort, using a 2017 production diesel engine as a baseline, demonstrated a combination of technologies that enabled Low NOX emission levels near the 90% reduction target, while at the same time maintaining GHG emission rates at the same levels as the base engine.
Previous publications have gone into detail regarding individual elements of the Stage 3 technology package. This paper will present a summary of the final configuration and final results of the Stage 3 program, including results for the fully aged aftertreatment system after the equivalent of 435,000 miles of operation. The performance of the final test article will be shown over a variety of both regulatory duty cycles and other off-cycle operations. The final fuel consumption and GHG performance of the system will also be described based on the benchmarking methods specified by EPA in the Phase 2 GHG standards.
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The measurement of solid particles down to 10 nm is being incorporated into global technical regulations (GTR). This study explores the measurement of solid particles below 23 nm by using both current and proposed particle number (PN) systems having different volatile particle remover (VPR) methodologies and condensation particle counter (CPC) cutoff diameters. The measurements were conducted in dynamometer test cells using ten diesel and eight natural gas (NG) engines that were going under development for a variety of global emission standards. The PN systems measured solid PN from more than 700 test cycles. The results from the preliminary campaign showed a 10-280% increase in PN emissions with the inclusion of particles below 23 nm. In the main campaign of this study, with the utilization of the current PN system and an add-on CPC to measure sub-23 nm particles, results showed the sub-23 nm fraction averaged between 23-58% and 19-51% of the total particles for diesel and NG engines, respectively. Data from one of the NG engines data showed that the sub-23 nm fraction increased with the use of a catalytic stripper (CS) due to a decrease in solid particles >23 nm. Data from the NG engine also suggested slightly lower counts of sub-23 nm particles from PN systems with a CS. Diesel measurements demonstrated that sub-23 nm particles can be mostly urea particles, and their generation is triggered by the combination of diesel exhaust fluid (DEF) injection rate and a selective catalytic reduction (SCR) outlet temperature of 250°C or greater. A few measurements using B20 fuel reported 5% and 8% higher solid particle counts for >23 nm and >sub-23 nm, respectively, compared to ultra-low sulfur diesel (ULSD) fuel. Particulate Matter (PM) data collected showed no correlation with PN as expected.
div class="section abstract"> This review covers some of the major advances pertaining to reducing tailpipe emissions of greenhouse gases and criteria pollutants. Discussed are both new and upcoming regulations, and technologies being developed for improving engines and after-treatment systems.
There is clearly a focus on reducing greenhouse gas emissions in major countries, implemented through ambitious CO2 and electrification targets. Several mature IC engine (ICE) technologies are reviewed which promise to deliver double digit reductions in CO2 emissions. We cover some of these in detail, including gasoline compression ignition, pre-chamber combustion, water injection, and cylinder deactivation. Electrification of the powertrain and synergistic gains with advanced engine technologies are examined. The case is made for the need for cradle-to-grave analyses when evaluating various powertrain choices, and highlight the role hybrids can play in achieving significant and immediate CO2 reductions. For the first time, also briefly discussed are the role of advanced fuels and their potential for improving emissions.
On criteria pollutants, the focus remains on reducing NOx and particulates. California is leading the charge on an omnibus rulemaking for heavy-duty trucks, targeting a 90% reduction in NOx emissions, and elements of the proposal are discussed. The challenge is to achieve this reduction without affecting CO2 emissions. Various studies are underway and technological pathways are being proposed and we cover the leading concepts. These include close-coupled SCR with dual dosing, innovative solutions for low temperature urea dosing, cylinder deactivation, advanced combustion techniques, electrification and natural gas engines.
For light-duty vehicles, real-world driving emission (RDE) norms seem to be addressing the discrepancy between lab and on-road NOx emissions, and the relevant data are discussed. Discussions are ongoing for post Euro-6 light duty regulations, and both the possible regulatory changes as well as after-treatment system developments are covered. A major focus will remain on reducing cold-start emissions and studies for both diesel and gasoline engines are reviewed.
Particle number standards in Europe and China have enforced gasoline particulate filters (GPFs) in those markets, and improvements in that technology are summarized. Filtration efficiency requirements are expected to increase with further tightening of regulations, and GPFs are also expected to be required for port fuel injected vehicles in the future.
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A production calibrated GTDI 1.6L Ford Fusion was used to demonstrate low HC, CO, NOx, PM (particulate mass), and PN (particulate number) emissions using advanced catalyst technologies with newly developed high porosity substrates and coated GPFs (gasoline particulate filters). The exhaust system consisted of 1.2 liters of TWC (three way catalyst) in the close-coupled position, and 1.6L of coated GPF in the underfloor position. The catalysts were engine-aged on a dynamometer to simulate 150K miles of road aging. Results indicate that ULEV70 emissions can be achieved at ∼$40 of PGM, while also demonstrating PM tailpipe performance far below the proposed California Air Resources Board (CARB) LEV III limit of 1 mg/mi. Along with PM and PN analysis, exhaust system backpressure is also presented with various GPF designs.
Testing was performed on Corning`s Generation 3 Electrically Heated Catalyst (EHC) to determine product reliability and durability. A number of functional measurements was performed before and after all electrical, thermal/mechanical and environmental tests. EHCs were also successfully tested on vehicles for 100,000 miles. The results of all tests were favorable and indicated that the new design meets or exceeds requirements.
Diesel particle filters (DPF) have become a standard after treatment component for all current and future on-road diesel engines used in the US. In Europe the introduction of EUVI is expected to also result in the broad implementation of DPF's. The anticipated general trend in engine technology towards higher engine out NOx/PM ratios results in a somewhat changing set of boundary conditions for the DPF predominantly enabling passive regeneration of the DPF. This enables the design of a novel filter concept optimized for low pressure drop, low thermal mass for optimized regeneration and fast heat-up of a downstream SCR system, therefore reducing CO 2 implications for the DPF operation. In this paper we will discuss results from a next generation cordierite DPF designed to address these future needs. The new materials are based on a thinwall design with optimized material and microstructure, resulting in an almost linear pressure drop response with soot loading in the bare and catalyzed state. A significant reduction in soot loaded pressure drop for uncoated and coated filters is demonstrated of the new filter design vs. current EPA 2010 filter technologies. The optimized microstructure also enables high filtration efficiency for mass and number. Results from a wide range of regeneration experiments will be used to discuss the thermal operating window of the new material and the thermal response during normal operation and active regeneration. A uniform temperature distribution and the fast thermal response of the low mass filter minimize implications on fuel consumption.
Investigation of emissions and gasoline particulate filter performance for sub 23 nm particles
- Chijiiwa
Axially Assembled Enclosure For Electrical Fluid Heater Having A Peripheral Compression Ring Producing A Diametrically Balanced Force
- J G Anderson
- T A Collins
- L E Hampton
Aftertreatment technologies supporting the path towards zero-impact emissions
- Rose
Future regulatory technology options to reduce risk in application for heavy-duty diesel engines
- Webb