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With the increasing number of hybrid vehicles in the Chinese market, research on aftertreatment systems for hybrid vehicles has become very popular. China has currently implemented national on-road China 6 regulations for emission control of all gasoline and diesel vehicles, including hybrid ones. So far, there are few papers on the optimization of aftertreatment for hybrid gasoline vehicles. Due to the introduction of electric motors in hybrid vehicles, the engine starts frequently and leads to inconsistent stability of engine operating conditions and brings the challenge to emission control of engine exhaust. This article selects a highly popular hybrid gasoline vehicle in China for research, which is a dual-mode hybrid (DM hybrid) passenger car. There is an obvious correlation between the emissions between the driving pattern and the hybrid strategy.

The impending emission regulations in both China (CN7) and the United States (Tier 4) are set to impose more stringent emission limits on hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx), and particulate matter (PM). CN7 places particular emphasis on reducing particulate number (PN) thresholds, while the forthcoming United States Tier 4 legislation is primarily concerned with reducing the allowable particulate matter (PM) to an assumed limit of 0.5 mg/mile. Given the more stringent constraints on both PN and PM emissions, the development of enhanced aftertreatment solutions becomes imperative to comply with these new regulatory demands. Coated Gasoline Particulate Filters (cGPFs) play a pivotal role as essential components for effective PN and PM abatement.

The proposed Euro-7 regulations are expected to build on the significant emissions reductions that have already been achieved using advanced Euro VI compliant after treatment systems (ATS). The introduction of in-service conformity (ISC) requirements during Euro VI paved the way for enabling compliance during real-world driving conditions. The diverse range of applications and resulting operating conditions greatly impact ATS design and the ability of the diesel particulate filter (DPF) to maintain performance under the most challenging boundary conditions including cold starts, partial/complete regenerations, and high passive soot burn operation. The current study attempts to map the particle number (PN) filtration performance of different DPF technologies under a variety of in-use cycles developed based on field-data from heavy duty Class-8 / N3 vehicles.

Smoke emission from compression ignition (CI) engines is directly tied to fuel atomization, vaporization, mixing and combustion processes. Engine boundary conditions such as ambient pressures and temperatures, particularly at higher altitudes, have significant impacts on both available ignition energy and on the mixing-controlled combustion process. However, the effects of boundary conditions are difficult to explore without thorough pressure and temperature control of the engine intake air and exhaust gas at higher altitude conditions. The objective of this research is to investigate the relationship between engine smoke emission and engine power in a CI engine fueled with jet fuel at various ambient conditions including higher altitudes. A multi-cylinder compression-ignition engine was operated on a jet fuel at various ambient pressure and temperature conditions, as low as 60 kPa and -12°C, respectively. Single and multi-injection strategies were applied depending on engine power.

A DMS500 engine exhaust particle size spectrometer was employed to characterize the effects of injection strategies on particulate emissions from a turbocharged gasoline direct injection (GDI) engine. The effects of operating parameters (injection pressure, secondary injection ratio and secondary injection end time) on particle diameter distribution and particle number density of emission were investigated. The experimental result indicates that the split injection can suppress the knocking tendency at higher engine loads. The combustion is improved, and the fuel consumption is significantly reduced, avoiding the increase in fuel pump energy consumption caused by the 50 MPa fuel injection system, but the delayed injection increases particulate matter emissions.

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).

Biodiesel (i.e., mono-alkyl esters of long chain fatty acids derived from vegetable oils and animal fats) is a renewable diesel fuel providing life-cycle greenhouse gas emission reductions relative to petroleum-derived diesel. With the expectation that there would be widespread use of biodiesel as a substitute for ultra-low sulfur diesel (ULSD), there have been many studies looking into the effects of biodiesel on engine and aftertreatment, particularly its compatibility to the current aftertreatment technologies. The objective of this study was to generate experimental data to measure the effectiveness of a current technology diesel oxidation catalysts (DOC) to oxidize soy-based biodiesel at various blend levels with ULSD. Biodiesel blends from 0 to 100% were evaluated on an engine using a conventional DOC.

The Bendix Wingman Fusion – a radar and camera collision mitigation system (CMS) available on commercial vehicles – was evaluated in two separate test series to determine its performance in simulated rear collision scenarios. In the first series of tests, evaluations were conducted in daytime, nighttime, and rainy conditions between 15 to 58 miles per hour (mph) to evaluate the performance of the audible and visual forward collision warning (FCW) system in a first-generation Bendix Wingman Fusion CMS while approaching a stationary live vehicle target (SLVT) in a 2017 Kenworth T680. A second test series was conducted with a 2017 Kenworth T680 traveling at 50 mph in daytime conditions approaching a decelerating vehicle to evaluate the Bendix Wingman Fusion CMS on the truck. Both test series sought to determine the maximum distance the system would warn prior to the test driver swerving around the SLVT or moving vehicle target.

As global regulations on automotive tailpipe emissions become increasingly stringent, developing precise tailpipe emissions models has garnered significant attention to fulfill onboard monitoring requirements without some drawbacks associated with traditional sensor-based systems. Within the European Union, there is consideration of mandating real-time measurement of emission constituents to enable driver warnings in cases where constituent standards are exceeded. Presently, available technology renders this approach cost-prohibitive and technologically challenging, with most sensor suppliers either unable to meet the demand or unwilling to justify the development costs associated with sensor commercialization. Efforts to circumvent the sensor-based approach through first principle models, incorporating thermokinetics, have proven to be both computationally expensive and lacking in accuracy during transient operations.

Biodiesel is a promising alternative to traditional diesel fuel due to its similar combustion properties to diesel and lower carbon emissions on a well-to-wheel basis. However, combusting biodiesel still generates hydrocarbon (HC), CO, NOx and particulate matter (PM) emissions, similar to those from traditional diesel fuel usage. Therefore, aftertreatment systems will be required to reduce these emissions to meet increasingly stringent emission regulations to minimize the impact to the environment. Diesel oxidation catalysts (DOC) are widely used in modern aftertreatment systems to convert unburned HC and CO, to partially convert NO to NO2 to enhance downstream selective catalytic reaction (SCR) catalyst efficiency via fast SCR and to periodically clean-up DPF via controlled soot oxidation. In this work, we focus on the performance difference between biodiesel and diesel over a commercial DOC catalyst to identify the knowledge gap during the transition from diesel fuel to biodiesel.

The steam reforming of CH4 plays a crucial role in the high-temperature activity of natural gas three-way catalysts. Despite existing reports on sulfur inhibition in CH4 steam reforming, there is a limited understanding of sulfur storage and removal dynamics under various lambda conditions. In this study, we utilize a 4-Mode sulfur testing approach to elucidate the dynamics of sulfur storage and removal and their impact on three-way catalyst performance. We also investigate the influence of sulfur on CH4 steam reforming by analyzing CH4 conversions under dithering, rich, and lean reactor conditions. In the 4-Mode sulfur test, saturating the TWC with sulfur at low temperatures emerges as the primary cause of significant three-way catalyst performance degradation. After undergoing a deSOx treatment at 600 °C, NOx conversions were fully restored, while CH4 conversions did not fully recover.

Design, testing, and implementation of new aftertreatment devices under various engine operating conditions is necessary to meet increasingly stringent regulatory mandates. One common aftertreatment device, the catalytic converter, is typically developed at a reduced scale and tested using predefined fluid compositions sourced from bottle gases and can undergo both species and temperature cycling in addition to steady-state testing. However, these bench-top conditions may differ from real-world operation in terms of flow-rates, species composition, and temperatures experienced. Transitioning from small-scale bench-top testing to full-scale engine applications requires larger monoliths that therefore have a significant amount of catalyst slurry to be washcoated, which increases cost and fabrication time.

Hydrogen (H2) is commonly considered as one of the most promising carbon-free energy carriers allowing for a decarbonization of combustion applications, for instance by retrofitting of conventional diesel internal combustion engines (ICEs). Although modern H2-ICEs emit only comparably low levels of nitrogen oxides (NOx), efficient catalytic converters are mandatory for exhaust gas after-treatment in order to establish near-zero emission applications. In this context, the present study evaluates the performance of a commercial state-of-the-art oxidation catalyst (OC) and of a catalyst for selective catalytic reduction (SCR) that are typically used for emission reduction from diesel exhausts under conditions representative for H2-fueled ICEs, namely oxygen-rich exhausts with high water vapor levels, comparably low temperatures, and potentially considerable levels of unburnt H2.

Spark ignition engines utilize catalytic converters to reform harmful exhaust gas emissions such as carbon monoxide, unburned hydrocarbons, and oxides of nitrogen into less harmful products. Aftertreatment devices require the use of expensive catalytic metals such as platinum, palladium, and rhodium. Meanwhile, tightening automotive emissions regulations globally necessitate the development of high-performance exhaust gas catalysts. So, automotive manufactures must balance maximizing catalyst performance while minimizing production costs. There are thousands of different recipes for catalytic converters, with each having a different effect on the various catalytic chemical reactions which impact the resultant tailpipe gas composition. In the development of catalytic converters, simulation models are often used to reduce the need for physical parts and testing, thus saving significant time and money.

Stoichiometric natural gas (CNG) engines are an attractive solution for heavy-duty vehicles considering their inherent advantage in emitting lower CO2 emissions compared to their Diesel counterparts. Additionally, their aftertreatment system can be simpler and less costly as NOx reduction is handled simultaneously with CO/HC oxidation by a Three-Way Catalyst (TWC). The conversion of methane over a TWC shows a complex behavior, significantly different than non-methane hydrocarbons in stoichiometric gasoline engines. Its performance is maximized in a narrow A/F window and is strongly affected by the lean/rich cycling frequency. Experimental and simulation results indicate that lean-mode efficiency is governed by the palladium’s oxidation state while rich conversion is governed by the gradual formation of carbonaceous compounds which temporarily deactivate the active materials.

The proposed Euro 7 regulation aims to substantially reduce the NOx emissions to 0.03 g/km, a trend also seen in upcoming China 6b and US EPA regulations. Meeting these stringent requirements necessitates advancements in Urea/Selective Catalytic Reduction (SCR) aftertreatment systems, with the urea deposit formation being a key challenge to its design. It’s proven that Computational Fluid Dynamics (CFD) can be an effective tool to predict Urea deposits. Transient wall temperature prediction is crucial in Urea deposit modeling. Additionally, fully understanding the kinetics of urea decomposition and by-products solidification are also critical in predicting the deposit amount and its location. In this study, we introduce (i) a novel film boiling model (IFPEN-BRT model) and (ii) a new urea by-product solidification model in the CONVERGE CFD commercial solver, and validate the results against the recent experiments.

The target of the upcoming automotive emission regulations is to promote a fast transition to near-zero emission vehicles. As such, the range of ambient and operating conditions tested in the homologation cycles is broadening. In this context, the proposed work aims to thoroughly investigate the potential of post-oxidation phenomena in reducing the light-off time of a conventional three-way catalyst. The study is carried out on a turbocharged four-cylinder gasoline engine by means of experimental and numerical activities. Post oxidation is achieved through the oxidation of unburned fuel in the exhaust line, exploiting a rich combustion and a secondary air injection dedicated strategy. The CFD methodology consists of two different approaches: the former relies on a full-engine mesh, the latter on a detailed analysis of the chemical reactions occurring in the exhaust line.

In this study, an integrated emission prediction model was used to predict whether EURO7-compliant commercial internal combustion engine vehicles would be able to meet upcoming regulations. In particular, the optimal value of Adblue injection and EHC (Electrically Heated Catalyst) control strategy for each combination of the specifications of the close-coupled SCR system (volume, substrate spec., EHC, etc.) was derived. Through this, it was intended to derive the best specification combination in terms of control and emission performance, and to use the results as a basis for decision-making in the early stages of product concept selection.

Hydrogen Internal Combustion Engines (H2 ICE) are gaining recognition as a nearly emission-free alternative to traditional ICE engines. However, H2 ICE systems face challenges related to thermal management, N2O emissions, and reduced SCR efficiency in high humidity conditions (15% H2O). This study assesses how hydrogen in the exhaust affects after-treatment system components for H2 ICE engines, such as Selective Catalytic Reduction (SCR), Hydrogen Oxidation Catalyst (HOC), and Ammonia Slip Catalyst (ASC). Steady-state experiments with inlet H2 inlet concentrations of 0.25% to 1% and gas stream moisture levels of up to 15% H2O were conducted to characterize the catalyst response to H2 ICE exhaust. The data was used to calibrate and validate system component models, forming the basis for a system simulation.

Air pollution is a significant environmental issue, and exhaust emissions from internal combustion engines are one of the primary sources of harmful pollutants. The transportation sector, which includes road vehicles, contributes to a large share of these emissions. In Europe, the latest emission legislation (Euro 7) proposes more stringent limits and testing conditions for vehicle emissions. To meet these limits, the automotive industry is actively developing innovative exhaust emission-control technologies. With the growing prevalence of electrification, internal combustion engines are subject to continuous variations in load and engine speed, including phases where the engine is switched off. The result is an operating condition characterized by successive cold starts. In this context, the challenge in coping with the emission limits is to minimize the light-off time and prevent fast light-out conditions during idling or city driving.