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This review summarizes the latest developments in diesel emissions regarding regulations, engines, NOx (nitrogen oxides) control, particulate matter (PM) reductions, and hydrocarbon (HC) and CO oxidation. Regulations are advancing with proposals for PN (particle number) regulations that require diesel particulate filters (DPFs) for Euro VI in 2013-14, and SULEV (super ultra low emission vehicle) fleet average light-duty (LD) emissions likely to be proposed in California for ~2017. CO₂ regulations will also impact diesel engines and emissions, probably long into the future. Engine technology is addressing these needs. Heavy-duty (HD) research engines show 90% lower NOx at the same PM or fuel consumption levels as a reference 2007 production engine. Work is starting on HD gasoline engines with promising results. In light duty (LD), engine downsizing is progressing and deNOx is emerging as a fuel savings strategy.

India BS6 Stage2 (2023) regulations demand all gasoline direct injection (GDI) vehicles to meet particulate number emissions (PN) below 6x10+11# per km. Gasoline particulate filters (GPF) are a proven technology and enable high PN filtration efficiencies throughout the entire vehicle lifetime. One challenge for GPF applications could be the changing emission performance characteristics as a function of mileage due to collected ash and/or soot deposits with implications on back pressure losses. The main objective of this technical contribution is to study the above-mentioned challenges while applying Indian driving conditions and typical Indian climate and other ambient conditions. The substrate technology selected for this study is a high porosity GPF designed to enable the integration of a three-way functionality into the GPF, commonly described as catalyzed GPF (cGPF).

This review paper summarizes major developments in vehicular emissions regulations and technologies from 2014. The paper starts with the key regulatory advancements in the field, including newly proposed Non-Road Mobile Machinery regulations for 2019-20 in Europe, and the continuing developments towards real driving emissions (RDE) standards. An expert panel in India proposed a roadmap through 2025 for clean fuels and tailpipe regulations. LD (light duty) and HD (heavy-duty) engine technology continues showing marked improvements in engine efficiency. Key developments are summarized for gasoline and diesel engines to meet both the emerging NOx and GHG regulations. HD engines are demonstrating more than 50% brake thermal efficiency using methods that can reasonably be commercialized. Next, NOx control technologies are summarized, including SCR (selective catalytic reduction), lean NOx traps, and combination systems. Emphasis is on durability and control.

This review paper summarizes major and representative developments in vehicular emissions regulations and technologies from 2015. The paper starts with the key regulatory advancements in the field, including newly proposed Euro 6 type regulations for Beijing, China, and India in the 2017-20 timeframe. Europe is continuing developments towards real driving emissions (RDE) standards with the conformity factors for light-duty diesel NOx ramping down to 1.5X by 2021. The California heavy duty (HD) low-NOx regulation is advancing and may be proposed in 2017/18 for implementation in 2023+. LD (light duty) and HD engine technology continues showing marked improvements in engine efficiency. Key developments are summarized for gasoline and diesel engines to meet both the emerging criteria and greenhouse gas regulations. LD gasoline concepts are achieving 45% BTE (brake thermal efficiency or net amount of fuel energy gong to the crankshaft) and closing the gap with diesel.

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.

Diesel particle filters (DPF) have become a standard aftertreatment 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 CO₂ implications for the DPF operation. In this paper we will discuss results from a next-generation cordierite DPF designed to address these future needs.

This review paper summarizes major developments in vehicular emissions regulations and technologies (light-duty, heavy-duty, gasoline, diesel) in 2011. First, the paper covers the key regulatory developments in the field, including proposed criteria pollutant tightening in California; and in Europe, the newly proposed PN (particle number) regulation for direct injection gasoline engines, test cycle development, and in-use testing discussions. The proposed US LD (light-duty) greenhouse gas (GHG) regulation for 2017-25 is reviewed, as well as the finalized, first-ever, US HD (heavy-duty) GHG rule for 2014-17. The paper then gives a brief, high-level overview of key emissions developments in LD and HD engine technology, covering both gasoline and diesel. Emissions challenges include lean NOx remediation for diesel and lean-burn gasoline to meet both the emerging NOx and GHG regulations.

The current automotive catalytic converter is highly dependable and provides excellent emissions reduction while at the same time it offers little resistance to the flow of gasses through the exhaust system. As automobile performance requirements increase, and as the allowable tailpipe emissions are tightened, there is a need on the one hand to reduce the back pressure even further, and on the other, to increase the already excellent catalytic performance. This paper will analyze the substrate factors which influence the pressure drop and conversion efficiency of the catalyst system. The converter frontal area has the most significant influence on both pressure drop and conversion efficiency, followed in order by part length, cell density, and wall thickness.

This review article summarizes major and representative developments in vehicle emissions regulations, engine efficiency, and emission control from 2017. The article starts with the key regulatory developments in the field, including newly proposed European light-duty (LD) CO2 regulations (15 and 30% cuts in 2025 and 2030, respectively, from 2020 levels) and technical improvements of the Euro 6 real driving emissions (RDE) regulations. China finalized their new energy vehicle (NEV) mandates for 2019 and 2020. LD and heavy-duty (HD) engine technology continues showing marked improvements in engine efficiency. Key developments are summarized for gasoline and diesel engines to meet both the emerging criteria and greenhouse gas (GHG) regulations. Several LD gasoline concepts are achieving 10-15% and some up to 35% reductions relative to gasoline direct injection (GDI) engines of today.

With stricter emissions standards, low back pressure requirements, and 100,000 mile durability specifications, ceramic catalysts have undergone significant developments over the past few years. The thrust in the ceramics area has centered on thin-wall structures to minimize back pressure and on high cell density for rapid light-off in close-coupled applications. The thin-wall structures are extruded from low expansion cordierite ceramic with adequate strength and thermal shock resistance equivalent to those of standard cordierite substrate. Examples of thin-wall substrate include 350XT which is extruded from a very low expansion dense cordierite ceramic, and 400/4 and 600/4 cell structures extruded from a low expansion modified cordierite ceramic. This paper will focus on the high fatigue resistance, excellent conversion efficiency, and low back pressure of 350 XT substrates with advanced washcoat system.

Particulate emission from diesel engines is one of the most important pollutants in urban areas. As a result, particulate emission control from urban bus diesel engines using particle filter technology is being evaluated at several locations in the US. A project entitled “Clean Diesel Demonstration Program” has been initiated by NY City Transit under the supervision of NY State DEC and with active participation from several industrial partners. Under this program, several NY City transit buses with DDC Series 50 engines have been equipped with continuously regenerating diesel particulate filter system and are operating with ultra low sulfur diesel (< 30 ppm S) in transit service in Manhattan since February 2000. These buses are being evaluated over a 8-9 month period for operations, maintainability and durability of the particulate filter.

An analytical model for estimating shear and bending stresses during canning of cordierite ceramic catalyst supports is presented. These stresses arise when the radial pressure distribution is nonuniform due, primarily, to variations in gap bulk density (GBD ) of intumescent mat around the perimeter of the substrate. Variations in GBD can occur during canning, regardless of the canning technique, due to anisotropic can stiffness or component tolerances or mat overlap. The model helps relate shear and bending stresses to substrate size and orientation, elastic modulii, cell size and wall porosity. If these stresses approach the corresponding strength of substrate, a shear crack may develop during or after the canning process depending on the magnitude of stress. A special test fixture was developed to measure the shear strength of ceramic catalyst supports, with different cell sizes, before and after the application of washcoat.

This paper gives a comprehensive overview of the current state-of-the-art in diesel emission control. The nature of diesel particulates is summarized. The variety of diesel particulate filter regeneration strategies that will become so important to filter application are reviewed. Filter retrofit and durability issues are addressed. DeNOx catalysts, SCR, NOx traps for diesel, and non-thermal plasma methods are summarized. Integrated NOx/PM systems are described. And reduction of exhaust toxics is discussed. The paper covers all major conferences in the year 2000 that occurred in the US and Europe. US and Europe.

Cordierite has been the cost-effective material of choice for diesel particulate filters (DPFs) for heavy duty vehicles due to its combination of excellent thermal shock resistance, filtration efficiency, and durability under most operating conditions. However, it has been observed that under some conditions of uncontrolled regeneration at moderately high soot loading, localized regions of melting in cordierite DPF bodies can occur. A new cordierite monolithic diesel particulate filter has been developed for medium and heavy duty trucks for OEM and retrofit applications. Through modification in pore microstructure and filter cell geometry, this new DPF provides improved survivability during uncontrolled regenerations, reduced pressure drop, and improved thermal shock resistance and strength.

In urban areas, particulate emission from diesel engines is one of the pollutants of most concern. As a result, particulate emission control from urban bus diesel engines using particle filter technology is being evaluated at several locations in the US. A project entitled, “Clean Diesel Vehicle Air Quality Project” has been initiated by NY City Transit under the supervision of NYSDEC and with active participation from several industry partners. Under this program, 25 NY City transit buses with DDC Series 50 engines have been equipped with continuously regenerating diesel particulate filter systems and have been operating with ultra low sulfur diesel (< 30 ppm S) in transit service in Manhattan since February 2000. These buses were evaluated over a 9 month period for operations, maintainability and durability of the particulate filter.

Quantitative in-use pressure measurements were taken from packaging ceramic substrates with the SoftMountSM technology and two more traditional technologies, stuffing and tourniquet. Each technology was assessed using four separate mat materials. Mat selection enhanced the application of the SoftMountSM technology through the reduced pressures applied to the substrate during packaging. High temperature and low temperature thermal cycling studies were performed on the canned converters for the three packaging technologies so that an evaluation could be made of converter durability. The SoftMountSM packaging technology yielded the lowest pressures of all the processes studied, regardless of mat type. The laminar hybrid mat evaluated yielded the best combination of pressure and durability performance. Low temperature residual shear strengths following thermal cycling of the converters showed good correlation between the SoftMountSM technology and the stuffing method.

To meet the future emission targets for Diesel engines, one trend is the use of Catalyzed Diesel Particulate Filters (CDPF). Catalyzing the filter, however, alters filter behavior. In particular, alteration in filter permeability imparts a significant change in the filter's performance. To understand the impact of the catalyst coating on a DPF, engine tests have been conducted to measure the pressure drop across DPFs with different catalyst coatings, cell densities, and soot loadings. The tests were performed over a range of engine speeds and loads, with a corresponding range in exhaust flow rates and temperatures. A pressure drop model based on previous work for uncatalyzed filters has been modified and validated for CDPFs. To achieve optimum design for DPF's, a parametric study comparing the influence of catalyst, cell density, wall thickness, filter length and diameter was done.

Efficient aftertreatment management requires accurate sensing of both particulate filter soot and ash levels for optimized feedback control. Currently a combination of pressure drop measurements and predictive models are used to indirectly estimate the loading state of the filter. Accurate determination of filter soot loading levels is challenging under certain operating conditions, particularly following partial regeneration events and at low flow rate (idle) conditions. This work applied radio frequency (RF)-based sensors to provide a direct measure of the particulate filter soot levels in situ. Direct measurements of the filter loading state enable advanced feedback controls to optimize the combined engine and aftertreatment system for improved DPF management. This study instrumented several cordierite and aluminum titanate diesel particulate filters with RF sensors. The systems were tested on a range of light- and heavy-duty applications, which included on- and off-road engines.

This review paper summarizes major and representative developments in vehicle engine efficiency and emissions regulations and technologies from 2016. The paper starts with the key regulatory developments in the field, including newly proposed European RDE (real driving emissions) particle number regulations, and Euro 6 type regulations for China and India in the 2020 timeframe. China will be tightening 30-40% relative to Euro 6 in 2023. The California heavy duty (HD) low-NOx regulation is advancing and the US EPA is anticipating developing a harmonized proposal for implementation in 2023+. The US also finalized the next round of HD GHG (greenhouse gas) regulations for 2021-27, requiring 5% engine CO2 reductions. LD (light duty) and HD engine technology continues showing marked improvements in engine efficiency. Key developments are summarized for gasoline and diesel engines to meet both the emerging criteria and greenhouse gas regulations.

In April 2003, a small field study was initiated to evaluate the effect of lube oil formulations on ash accumulation in heavy-duty diesel DPFs. Nine (9) Fuel Delivery Trucks were retrofitted with passive diesel particulate filters and fueled with ultra low sulfur diesel which contains less than 15 ppm sulfur. Each vehicle operated in the field for 18 months or approximately 160,000 miles (241,401 km) using one of three lube oil formulations. Ash accumulation was determined for each vehicle and compared between the three differing lube oil formulations. Ash analyses, used lube oil analysis and filter substrate evaluations were performed to provide a complete picture of DPF operations. The evaluation also examined some of the key parameters that allows for the successful implementation of the passive DPF in this heavy-duty application.